Add files using upload-large-folder tool

marked/Y/T-REC-F.747.1-201206-I_PDF-E/raw.md

@@ -0,0 +1,703 @@
+
+
+I n t e r n a t i o n a l   T e l e c o m m u n i c a t i o n   U n i o n
+
+# ITU-T
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+## F.747.1
+
+(06/2012)
+
+SERIES F: NON-TELEPHONE TELECOMMUNICATION  
+SERVICES
+
+Audiovisual services
+
+# --- **Capabilities of ubiquitous sensor networks for supporting the requirements of smart metering services**
+
+Recommendation ITU-T F.747.1
+
+![ITU logo: a blue globe with red lightning bolts and the text 'ITU International Telecommunication Union'](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with two red lightning bolts striking it. To the right of the globe, the text "ITU" is written in a large, bold, blue font, and below it, the words "International Telecommunication Union" are written in a smaller, blue font.
+
+ITU logo: a blue globe with red lightning bolts and the text 'ITU International Telecommunication Union'
+
+## ITU-T F-SERIES RECOMMENDATIONS **NON-TELEPHONE TELECOMMUNICATION SERVICES**
+
+|                                                                 |                    |
+|-----------------------------------------------------------------|--------------------|
+| <b>TELEGRAPH SERVICE</b>                                        |                    |
+| Operating methods for the international public telegram service | F.1–F.19           |
+| The gentex network                                              | F.20–F.29          |
+| Message switching                                               | F.30–F.39          |
+| The international telemessage service                           | F.40–F.58          |
+| The international telex service                                 | F.59–F.89          |
+| Statistics and publications on international telegraph services | F.90–F.99          |
+| Scheduled and leased communication services                     | F.100–F.104        |
+| Phototelegraph service                                          | F.105–F.109        |
+| <b>MOBILE SERVICE</b>                                           |                    |
+| Mobile services and multideestination satellite services        | F.110–F.159        |
+| <b>TELEMATIC SERVICES</b>                                       |                    |
+| Public facsimile service                                        | F.160–F.199        |
+| Teletex service                                                 | F.200–F.299        |
+| Videotex service                                                | F.300–F.349        |
+| General provisions for telematic services                       | F.350–F.399        |
+| <b>MESSAGE HANDLING SERVICES</b>                                | <b>F.400–F.499</b> |
+| <b>DIRECTORY SERVICES</b>                                       | <b>F.500–F.549</b> |
+| <b>DOCUMENT COMMUNICATION</b>                                   |                    |
+| Document communication                                          | F.550–F.579        |
+| Programming communication interfaces                            | F.580–F.599        |
+| <b>DATA TRANSMISSION SERVICES</b>                               | <b>F.600–F.699</b> |
+| <b>AUDIOVISUAL SERVICES</b>                                     | <b>F.700–F.799</b> |
+| <b>ISDN SERVICES</b>                                            | <b>F.800–F.849</b> |
+| <b>UNIVERSAL PERSONAL TELECOMMUNICATION</b>                     | <b>F.850–F.899</b> |
+| <b>HUMAN FACTORS</b>                                            | <b>F.900–F.999</b> |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **Recommendation ITU-T F.747.1**
+
+# **Capabilities of ubiquitous sensor networks for supporting the requirements of smart metering services**
+
+## **Summary**
+
+Recommendation ITU-T F.747.1 identifies the capabilities of ubiquitous sensor networks (USNs) for supporting the requirements of smart metering services. To this end, an overview of smart metering is described, with a clarification between smart grids and smart metering provided. This Recommendation takes into account a few typical use case scenarios of smart metering and identifies the general requirements and USN-based smart metering services to support these use cases. Finally this Recommendation defines USN capabilities based on identified requirements for providing smart metering services.
+
+## **History**
+
+| Edition | Recommendation | Approval   | Study Group |
+|---------|----------------|------------|-------------|
+| 1.0     | ITU-T F.747.1  | 2012-06-29 | 16          |
+
+## **Keywords**
+
+Smart grid, smart metering, USN.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2013
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                                  | <b>Page</b> |
+|--------------------------------------------------------------------------------------------------|-------------|
+| 1 Scope .....                                                                                    | 1           |
+| 2 References.....                                                                                | 1           |
+| 3 Definitions .....                                                                              | 1           |
+| 3.1 Terms defined elsewhere.....                                                                 | 1           |
+| 3.2 Terms defined in this Recommendation.....                                                    | 2           |
+| 4 Abbreviations and acronyms .....                                                               | 2           |
+| 5 Conventions .....                                                                              | 2           |
+| 6 Overview of smart metering .....                                                               | 2           |
+| 6.1 Smart grids and smart metering.....                                                          | 3           |
+| 6.2 Technical overview of smart metering.....                                                    | 5           |
+| 6.3 USN-based smart metering services.....                                                       | 5           |
+| 7 Smart metering service scenarios .....                                                         | 7           |
+| 7.1 Scenario I: Regularly scheduled remote meter reading.....                                    | 7           |
+| 7.2 Scenario II: On-demand remote meter reading .....                                            | 8           |
+| 7.3 Scenario III: Demand response .....                                                          | 9           |
+| 7.4 Scenario IV: Tariff configuration.....                                                       | 10          |
+| 7.5 Scenario V: Meter reading data aggregation.....                                              | 11          |
+| 8 Network and USN requirements for smart metering services.....                                  | 12          |
+| 8.1 Time synchronization .....                                                                   | 12          |
+| 8.2 Reliable information delivery.....                                                           | 12          |
+| 8.3 Minimal time delay.....                                                                      | 12          |
+| 8.4 Real-time delivery of meter reading data .....                                               | 12          |
+| 8.5 Bidirectional communication between meters and operators.....                                | 13          |
+| 8.6 Security support including the authorization of operator and data confidentiality.....       | 13          |
+| 8.7 Authentication of smart meters .....                                                         | 13          |
+| 8.8 Meter reading data processing.....                                                           | 13          |
+| 8.9 Monitoring and management of smart meters.....                                               | 13          |
+| 9 USN capabilities for smart metering services .....                                             | 13          |
+| 9.1 Time synchronization .....                                                                   | 13          |
+| 9.2 Reliable transmission.....                                                                   | 13          |
+| 9.3 Scalability .....                                                                            | 14          |
+| 9.4 Mobility support.....                                                                        | 14          |
+| 9.5 Delivery latency.....                                                                        | 14          |
+| 9.6 Fault detection and recovery .....                                                           | 14          |
+| 9.7 Security supporting confidentiality, integrity check, authorization and authentication ..... | 14          |
+| 9.8 Connectivity .....                                                                           | 14          |
+
+|                                                         | <b>Page</b> |
+|---------------------------------------------------------|-------------|
+| 9.9      Unicasting and multicasting .....              | 14          |
+| 9.10     Data aggregation.....                          | 14          |
+| 9.11     Distributed processing .....                   | 15          |
+| 9.12     Monitoring and management of sensor nodes..... | 15          |
+| Bibliography.....                                       | 16          |
+
+# Recommendation ITU-T F.747.1
+
+# Capabilities of ubiquitous sensor networks for supporting the requirements of smart metering services
+
+## 1 Scope
+
+The main purpose of this Recommendation is to identify the capabilities of ubiquitous sensor networks (USNs) which support the requirements of smart metering services. The scope of this Recommendation covers the following:
+
+- overview of smart metering
+- smart metering use case scenarios
+- requirements of smart metering services
+- USN capabilities for supporting the requirements of smart metering services.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T F.744] Recommendation ITU-T F.744 (2009), *Service description and requirements for ubiquitous sensor network middleware*.
+- [ITU-T Y.2221] Recommendation ITU-T Y.2221 (2010), *Requirements for support of ubiquitous sensor network (USN) applications and services in the NGN environment*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 sensor** [ITU-T Y.2221]: An electronic device that senses a physical condition or chemical compound and delivers an electronic signal proportional to the observed characteristic.
+
+**3.1.2 sensor network** [ITU-T Y.2221]: A network comprised of inter-connected sensor nodes exchanging sensed data by wired or wireless communication.
+
+**3.1.3 sensor node** [ITU-T Y.2221]: A device consisting of sensor(s) and optional actuator(s) with the capabilities of sensed data processing and networking.
+
+**3.1.4 ubiquitous sensor network (USN)** [ITU-T Y.2221]: A conceptual network built over existing physical networks which makes use of sensed data and provides knowledge services to anyone, anywhere and at any time, and where the information is generated by using context awareness.
+
+**3.1.5 USN gateway** [ITU-T Y.2221]: A node which interconnects sensor networks with other networks.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 demand response:** A smart metering feature that allows consumers to reduce or change their use patterns of electricity, gas and water during peak demand usually in exchange for a financial incentive.
+
+**3.2.2 sensor network gateway:** A sensor network element that connects a sensor network to another network with different architecture or protocols, permitting information exchange between them. See also USN gateway.
+
+NOTE – Sensor network gateway functionalities may include either address or protocol translation or both.
+
+**3.2.3 smart grid:** An electricity network that can intelligently integrate the actions of all users connected to it – generators, consumers and those that do both – in order to efficiently deliver sustainable, economic and secure electricity supplies.
+
+**3.2.4 smart meter:** A device in a user's premises for monitoring and controlling electrical power, gas and water usage of home appliances based on demand response information from home appliances.
+
+**3.2.5 smart metering:** An operation to provide information to consumers and smart metering operators about energy consumption. The information includes how much energy the consumers are using or generating and how much it costs.
+
+**3.2.6 smart metering gateway:** See USN gateway.
+
+**3.2.7 utility:** An entity providing services such electricity, gas, water and heating to the general public and/or to industrial and commercial entities.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+USN    Ubiquitous Sensor Network
+
+## 5 Conventions
+
+None.
+
+## 6 Overview of smart metering
+
+Smart meters are utility meters, for example electricity, gas, water and other meters, which may bring about the end of estimated bills and meter readings, and provide customers and energy distributors and suppliers with accurate information on the amount of a utility that is being used.
+
+Smart metering provides:
+
+- customers with the information they require to become energy savvy and make smarter decisions about their energy usage;
+- energy suppliers with the means to better understand and service their customers;
+- distributors with an effective tool to better monitor and manage their networks.
+
+In addition, smart metering enables those customers who choose to generate their own electricity (micro-generators) to be financially rewarded for their contribution to the national grid, and for distributors to better manage this contribution [b-ETSI TR 102 691].
+
+Smart metering may be regarded as one of the key technologies for smart grid systems.
+
+### **6.1 Smart grids and smart metering**
+
+A smart grid is a type of electrical grid that attempts to predict and intelligently respond to the behaviour and actions of all electric power users connected to it – suppliers, consumers and those that do both – in order to efficiently deliver reliable, economic and sustainable electricity services including:
+
+- enhancement of reliability
+- reducing peak demand
+- shifting usage to off-peak hours
+- lower total energy consumption
+- actively managing electricity charging
+- actively managing other usage to respond to other renewable resources.
+
+Smart grid technologies have already been used in other applications, such as manufacturing and telecommunications. In general, smart grid technology may be divided into seven areas: integrated communications, sensing and measurement, smart metering, advanced components, advanced control, improved interfaces and decision support, and smart power generation. In other words, smart meters are key components of smart grids and consequently, smart metering is one of the crucial features for smart grids.
+
+![Smart grid architecture diagram showing domains: Markets, Operations (RTO/ISO, Transmission, Distribution), Service providers (Utility, Third-party), Bulk generation, Transmission, Distribution, and Customer. It includes actors like Aggregators, SCADA systems, and various interfaces, connected by information networks and communication paths.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+The diagram illustrates the Smart grid architecture, organized into several domains and their interactions:
+
+- Markets:** Includes Retailer/wholesaler, Aggregator, Energy market clearing house, and ISO/RTO participant. These are connected to the Internet/e-Business information network.
+- Operations:**
+  - RTO/ISO Ops:** Contains EMS, Enterprise bus, and RTO SCADA.
+  - Transmission Ops:** Contains EMS, WAMS, Enterprise bus, and Transmission SCADA.
+  - Distribution Ops:** Contains DMS, Asset Mgmt, Demand response, MDMS, Enterprise bus, Metering system, and Distribution SCADA.
+- Service providers:**
+  - Utility provider:** Contains CIS, Billing, and Internet/e-Business.
+  - Third-party provider:** Contains Retail energy provider, CIS, Billing, Home/building manager, Aggregator, and Others.
+- Bulk generation:** Includes Market services interface, Plant control system, and Generators. It connects to Wide area networks.
+- Transmission:** Includes Wide area networks, Substation LANs, Substation controller, Substation device, Data collector, and Electric storage.
+- Distribution:** Includes Field area networks, Field device, and Distributed generation.
+- Customer:** Includes Premises networks, Energy services interface, Meter, Customer equipment, Customer EMS, Electric vehicle, Distributed generation, Electric storage, Appliances, and Thermostat.
+
+**Legend:**
+
+- Domain: Represented by a rounded rectangle.
+- Actor: Represented by a rectangle.
+- Information network: Represented by a cloud shape.
+- Domain gateway actor: Represented by a rectangle with a thick border.
+- Comms path: Represented by a dashed line.
+- Comms path across owner/domain: Represented by a solid line.
+
+F.747.1(12)\_F01
+
+Smart grid architecture diagram showing domains: Markets, Operations (RTO/ISO, Transmission, Distribution), Service providers (Utility, Third-party), Bulk generation, Transmission, Distribution, and Customer. It includes actors like Aggregators, SCADA systems, and various interfaces, connected by information networks and communication paths.
+
+**Figure 1 – Smart grid architecture [b-NIST]**
+
+### 6.2 Technical overview of smart metering
+
+It is not only governments and utility companies, such as electricity, gas and water suppliers, but also researchers, that have been interested in automatic meter reading based on communication systems. Examples of smart metering benefits to customers, governments and utility companies are:
+
+- lower metering cost
+- energy savings for residential consumers
+- reliability of supply
+- various pricing schemes to attract new costumers
+- easier detection of fraud and of outages
+- automated billing.
+
+Smart metering comprises metering and exchange of meter information between smart meters and utility companies. Various technologies can be used for metering and exchanging meter information. For example, power-line communications have been used for delivering electricity power to consumers and for transmitting gas and water measurements to utility providers. Alternatively, mobile networks can be used for exchanging messages in an automatic meter reading system.
+
+Sensor network technologies may be used for metering and collecting information of utility usage, and communication networks can be used for exchanging the information. Figure 2 depicts an overall diagram of smart metering systems. The meter information, obtained from home appliances by sensor nodes is collected and delivered to operators of utility companies.
+
+The operators manage the collected information and inform consumers of variable pricing information or enforced load control messages. Such operators' actions may lead to consumers' reducing energy consumption.
+
+![Figure 2: Overview of smart metering. The diagram shows a 'Smart home' containing 'Appliances' (Gas, Electricity, Water) connected to 'Smart meters' (Gas, Electricity, Water). These meters are connected to a 'Communication interface' which links to 'Communication networks' and finally to a 'Smart metering operator'.](5e92d9e8e9ce204e405bff2367f88176_img.jpg)
+
+The diagram illustrates the architecture of a smart metering system. On the left, a house labeled 'Smart home' contains a section labeled 'Appliances' with icons for a gas cylinder, a television, and a water tap. Below these are three circular nodes labeled 'Gas smart meter', 'Electricity smart meter', and 'Water smart meter'. These meters are connected to a 'Communication interface' at the bottom of the house. A line connects this interface to a cloud labeled 'Communication networks'. From the cloud, a line connects to a server rack labeled 'Smart metering operator'. The label 'F.747.1(12)\_F02' is located at the bottom right of the diagram.
+
+Figure 2: Overview of smart metering. The diagram shows a 'Smart home' containing 'Appliances' (Gas, Electricity, Water) connected to 'Smart meters' (Gas, Electricity, Water). These meters are connected to a 'Communication interface' which links to 'Communication networks' and finally to a 'Smart metering operator'.
+
+**Figure 2 – Overview of smart metering**
+
+### 6.3 USN-based smart metering services
+
+The smart metering services shown in Figure 3 require technological facilities to support metering, and to exchange metering information between smart meters and metering operators in utility control centres.
+
+The basic characteristic of USN applications and services are gathering data by sensor networks and data transmission to a remote server through communication networks. Also, control information is transmitted to sensor networks from the remote server. Furthermore, if USN middleware is deployed, the middleware can provide USN applications or sensor networks with various functions such as data query, data mining, event processing, sensor network metadata directory service, data filtering, context-aware rule processing and sensor network management.
+
+These USN features can be applied to smart metering services. Sensor nodes in sensor networks have the capabilities of metering and delivering metered information to a server at a utility control centre. USN middleware can provide functions which are required by an on-demand remote meter reading scenario and a demand response meter reading scenario.
+
+A smart metering system can be implemented by sensor nodes and USN middleware as follows:
+
+- Smart metering sensor nodes: Each sensor node may have smart metering capabilities, therefore, sensor nodes can act as smart meters supporting the processing of smart metering information for smart metering procedures, such as meter reading collection and tariff setting.
+- Smart metering gateway: A sensor network gateway or a USN gateway is capable of connecting a sensor network to another network with different architecture or protocols, permitting information exchange between them. Therefore a sensor network gateway or a USN gateway can be used as a smart metering gateway. A smart metering gateway is only responsible for delivering information between the sensor nodes (smart meters) and metering operators. In cases where a gateway has smart metering capabilities, it collects meter reading data and then delivers it to the metering operator(s).
+- USN middleware [ITU-T F.744]: USN middleware provides data filtering, data query, data mining and context-aware rule processing, etc. These features of USN middleware satisfy meter reading data processing requirements and can be applied to an on-demand remote meter reading scenario and a demand response meter reading scenario.
+
+![Figure 3: Smart metering services based on USN. The diagram illustrates a three-tier architecture. At the top, the 'Smart metering operator' is enclosed in a dashed box and contains several server icons and a cloud, with the label 'Servers a)'. This operator is connected to a central 'Transport network' cloud containing a mesh of nodes. Below the transport network, the 'Sensor networks' section is enclosed in a dashed box and includes two types of networks: a 'Smart home' and a 'Smart building'. Each network contains multiple 'Sensor node a) (smart metering)' icons. These sensor networks are connected to 'USN gateway a)' devices, which in turn connect to the transport network. A footnote at the bottom left states 'a) USN middleware is optionally included'. The bottom right corner is labeled 'F.747.1(12)_F03'.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+Figure 3: Smart metering services based on USN. The diagram illustrates a three-tier architecture. At the top, the 'Smart metering operator' is enclosed in a dashed box and contains several server icons and a cloud, with the label 'Servers a)'. This operator is connected to a central 'Transport network' cloud containing a mesh of nodes. Below the transport network, the 'Sensor networks' section is enclosed in a dashed box and includes two types of networks: a 'Smart home' and a 'Smart building'. Each network contains multiple 'Sensor node a) (smart metering)' icons. These sensor networks are connected to 'USN gateway a)' devices, which in turn connect to the transport network. A footnote at the bottom left states 'a) USN middleware is optionally included'. The bottom right corner is labeled 'F.747.1(12)\_F03'.
+
+**Figure 3 – Smart metering services based on USN**
+
+## 7 Smart metering service scenarios
+
+The following scenarios illustrate the use of smart metering services.
+
+### 7.1 Scenario I: Regularly scheduled remote meter reading
+
+Scenario I in Figure 4 describes procedures where meter reading data are delivered to smart metering operators at regularly scheduled intervals.
+
+- 1) A smart metering operator sends a message including schedule information to smart meters.
+- 2) Smart meters are configured with the schedule for measurement and data transfer.
+- 3) According to the schedule, smart meters measure energy consumption from home appliances and obtain measurement data.
+- 4) The smart meters deliver the data to the smart metering operator.
+
+![Sequence diagram for Scenario I: Regularly scheduled remote metering. The diagram shows interactions between Smart meter 1, Appliance 1, Smart meter 2, Appliance 2, and Smart metering operator. The process involves the operator sending schedule information to both smart meters, which then set their own measurement schedules. Subsequently, each smart meter performs a meter reading and sends metering information to its respective appliance. Finally, each smart meter sends metering information to the smart metering operator.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+```
+
+sequenceDiagram
+    participant S1 as Smart meter 1
+    participant A1 as Appliance 1
+    participant S2 as Smart meter 2
+    participant A2 as Appliance 2
+    participant SMO as Smart metering operator
+
+    SMO->>S1: Schedule information
+    SMO->>S2: Schedule information
+    S1->>S1: Setting schedule for measurement
+    S2->>S2: Setting schedule for measurement
+    S1->>S1: Meter reading
+    S1->>A1: Metering information
+    S2->>S2: Meter reading
+    S2->>SMO: Metering information
+    S1->>S1: Meter reading
+    S1->>A1: Metering information
+    S2->>S2: Meter reading
+    S2->>SMO: Metering information
+    S1->>S1: Meter reading
+    S1->>A1: Metering information
+    S2->>S2: Meter reading
+    S2->>SMO: Metering information
+  
+```
+
+Sequence diagram for Scenario I: Regularly scheduled remote metering. The diagram shows interactions between Smart meter 1, Appliance 1, Smart meter 2, Appliance 2, and Smart metering operator. The process involves the operator sending schedule information to both smart meters, which then set their own measurement schedules. Subsequently, each smart meter performs a meter reading and sends metering information to its respective appliance. Finally, each smart meter sends metering information to the smart metering operator.
+
+F.747.1(12)\_F04
+
+**Figure 4 – Scenario I: Regularly scheduled remote metering**
+
+### 7.2 Scenario II: On-demand remote meter reading
+
+Scenario II in Figure 5 describes the procedures for when smart meters measure energy consumption and deliver the results to a smart metering operator on demand.
+
+- 1) When a smart metering operator collects measurement data from the smart meters, the operator sends a task message for smart meters to collect measurement data.
+- 2) Smart meters verify the operator's message and, if the message is validated, they measure energy consumption.
+- 3) The resulting data are delivered to the smart metering operator.
+
+NOTE – Figure 5 does not include the flow for the message verification, as this can be performed in a number of ways.
+
+![Sequence diagram for Scenario II: On-demand remote meter reading. The diagram shows interactions between Smart meter 1, Appliance 1, Smart meter 2, Appliance 2, and Smart metering operator. The operator sends control messages to both smart meters. Each smart meter performs a self-read (Meter reading) and then sends Metering information to the operator.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg)
+
+```
+
+sequenceDiagram
+    participant S1 as Smart meter 1
+    participant A1 as Appliance 1
+    participant S2 as Smart meter 2
+    participant A2 as Appliance 2
+    participant SO as Smart metering operator
+
+    SO->>S1: Control message with a task
+    S1->>S1: Meter reading
+    S1->>SO: Metering information
+    SO->>S2: Control message with a task
+    S2->>S2: Meter reading
+    S2->>SO: Metering information
+    SO->>S1: Control message with a task
+    S1->>S1: Meter reading
+    S1->>SO: Metering information
+  
+```
+
+Sequence diagram for Scenario II: On-demand remote meter reading. The diagram shows interactions between Smart meter 1, Appliance 1, Smart meter 2, Appliance 2, and Smart metering operator. The operator sends control messages to both smart meters. Each smart meter performs a self-read (Meter reading) and then sends Metering information to the operator.
+
+F.747.1(12)\_F05
+
+**Figure 5 – Scenario II: On-demand remote meter reading  
+(excluding the verification step)**
+
+### 7.3 Scenario III: Demand response
+
+Scenario III illustrated in Figure 6 describes customers responding to the metering operator's demands.
+
+- 1) A smart metering operator sends a message including schedule information to smart meters.
+- 2) Smart meters are configured with the schedule for measurement and data transfer.
+- 3) When the number of home appliances turned on simultaneously is on the increase, the total amount of energy consumption also steeply increases.
+- 4) Information about the increasing amount of energy consumption is being reported to the smart metering operator at scheduled intervals, and the price of energy may also change according to the tariff policies (e.g., depending on supply and demand).
+- 5)
+  - (a) The smart metering operator sends a message to inform consumers of the price change.
+  - (b) The smart metering operator sends load control messages to enforce the reduction of energy consumption or to force shut off due to a management policy.
+- 6)
+  - (a) Smart meters display the message to the consumers, and the consumers may decide to reduce energy consumption, or the home appliances may be switched off by the consumer.
+  - (b) When receiving the load control messages, the smart meter displays the message and proceeds to shutting off the connected home appliance.
+
+![Sequence diagram for Scenario III: Demand response. The diagram shows interactions between Smart meter 1, Appliance 1, Smart metering operator, Smart meter 2, and Appliance 2. Key events include: 1. Smart metering operator sends 'Schedule information' to both smart meters. 2. Both smart meters perform a self-action 'Setting schedule for measurement'. 3. Smart meter 1 sends 'Meter reading' to Appliance 1. 4. Smart meter 2 sends 'Meter reading' to Appliance 2, which then performs a self-action 'Switched on'. 5. Both smart meters send 'Metering information' to the Smart metering operator. 6. The Smart metering operator sends 'Price of electricity changes' to both smart meters. 7. The Smart metering operator sends a 'Control message with the changed price information' to Smart meter 1 and a 'Control message to shut off electricity' to Smart meter 2. 8. Smart meter 1 performs a self-action 'Display the price changes of electricity', which then triggers Appliance 1 to perform a self-action 'Display the price changes of electricity' and a note 'Electricity consumption reduced by a consumer (or switched off)'. 9. Smart meter 2 performs a self-action 'Display message for shut-off', which then triggers Appliance 2 to perform a self-action 'Shut off electricity' and a note 'Automatically switched off'. 10. Both smart meters send 'Meter reading' to their respective appliances. 11. Both smart meters send 'Metering information' to the Smart metering operator.](fa859e4e468bfb2710a94527f2c504af_img.jpg)
+
+```
+
+sequenceDiagram
+    participant SMO as Smart metering operator
+    participant SM1 as Smart meter 1
+    participant A1 as Appliance 1
+    participant SM2 as Smart meter 2
+    participant A2 as Appliance 2
+
+    SMO->>SM1: Schedule information
+    SMO->>SM2: Schedule information
+    SM1->>SM1: Setting schedule for measurement
+    SM2->>SM2: Setting schedule for measurement
+    SM1->>A1: Meter reading
+    SM2->>A2: Meter reading
+    A2->>A2: Switched on
+    SM1->>SMO: Metering information
+    SM2->>SMO: Metering information
+    SMO->>SM1: Control message with the changed price information
+    SMO->>SM2: Control message to shut off electricity
+    SM1->>SM1: Display the price changes of electricity
+    A1->>A1: Display the price changes of electricity
+    Note over A1: Electricity consumption reduced by a consumer (or switched off)
+    SM2->>SM2: Display message for shut-off
+    A2->>A2: Shut off electricity
+    Note over A2: Automatically switched off
+    SM1->>A1: Meter reading
+    SM2->>A2: Meter reading
+    SM1->>SMO: Metering information
+    SM2->>SMO: Metering information
+  
+```
+
+Sequence diagram for Scenario III: Demand response. The diagram shows interactions between Smart meter 1, Appliance 1, Smart metering operator, Smart meter 2, and Appliance 2. Key events include: 1. Smart metering operator sends 'Schedule information' to both smart meters. 2. Both smart meters perform a self-action 'Setting schedule for measurement'. 3. Smart meter 1 sends 'Meter reading' to Appliance 1. 4. Smart meter 2 sends 'Meter reading' to Appliance 2, which then performs a self-action 'Switched on'. 5. Both smart meters send 'Metering information' to the Smart metering operator. 6. The Smart metering operator sends 'Price of electricity changes' to both smart meters. 7. The Smart metering operator sends a 'Control message with the changed price information' to Smart meter 1 and a 'Control message to shut off electricity' to Smart meter 2. 8. Smart meter 1 performs a self-action 'Display the price changes of electricity', which then triggers Appliance 1 to perform a self-action 'Display the price changes of electricity' and a note 'Electricity consumption reduced by a consumer (or switched off)'. 9. Smart meter 2 performs a self-action 'Display message for shut-off', which then triggers Appliance 2 to perform a self-action 'Shut off electricity' and a note 'Automatically switched off'. 10. Both smart meters send 'Meter reading' to their respective appliances. 11. Both smart meters send 'Metering information' to the Smart metering operator.
+
+F747.1(12)\_F06
+
+**Figure 6 – Scenario III: Demand response**
+
+### 7.4 Scenario IV: Tariff configuration
+
+Scenario IV, illustrated in Figure 7 describes how the price of energy consumption is decided and configured within the meters.
+
+- 1) A smart metering operator sends a message including schedule information to smart meters.
+- 2) Smart meters are set up with the schedule for measurement and data transfer.
+- 3) The smart meters regularly deliver meter reading data to the metering operator according to regularly scheduled intervals.
+- 4) The price of electricity may be dynamically changed by pricing policies (e.g., depending on supply and demand).
+- 5) When the price changes, a message including changed price information is delivered to all the smart meters concerned.
+- 6) The changed cost information may be shown on their displays, and the new cost is applied.
+
+![Sequence diagram for Scenario IV: Tariff configuration. The diagram shows interactions between Smart meter 1, Appliance 1, Smart metering operator, Smart meter 2, and Appliance 2. The process starts with the Smart metering operator sending 'Schedule information' to both Smart meter 1 and Smart meter 2. Each smart meter then performs a self-action 'Setting schedule for measurement'. Smart meter 1 sends 'Metering information' to the Smart metering operator, while Appliance 1 performs a self-action 'Meter reading'. Similarly, Smart meter 2 sends 'Metering information' to the Smart metering operator, while Appliance 2 performs a self-action 'Meter reading'. The Smart metering operator then sends 'Price of electricity changes' to both smart meters. Each smart meter performs a self-action 'Price of electricity changes' and then sends a 'Control message with the changed price information' to the Smart metering operator. The Smart metering operator then sends 'Control message with the changed price information' to both smart meters. Each smart meter performs a self-action 'Display the cost of electricity changes and new price applied'. Finally, each smart meter sends 'Metering information' to the Smart metering operator, while each appliance performs a self-action 'Meter reading'.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+```
+
+sequenceDiagram
+    participant SMO as Smart metering operator
+    participant SM1 as Smart meter 1
+    participant A1 as Appliance 1
+    participant SM2 as Smart meter 2
+    participant A2 as Appliance 2
+
+    SMO->>SM1: Schedule information
+    SMO->>SM2: Schedule information
+    SM1->>SM1: Setting schedule for measurement
+    SM2->>SM2: Setting schedule for measurement
+    SM1->>SMO: Metering information
+    A1->>A1: Meter reading
+    SM2->>SMO: Metering information
+    A2->>A2: Meter reading
+    SMO->>SM1: Price of electricity changes
+    SMO->>SM2: Price of electricity changes
+    SM1->>SM1: Price of electricity changes
+    SM2->>SM2: Price of electricity changes
+    SM1->>SMO: Control message with the changed price information
+    SM2->>SMO: Control message with the changed price information
+    SMO->>SM1: Control message with the changed price information
+    SMO->>SM2: Control message with the changed price information
+    SM1->>SM1: Display the cost of electricity changes and new price applied
+    SM2->>SM2: Display the cost of electricity changes and new price applied
+    SM1->>SMO: Metering information
+    A1->>A1: Meter reading
+    SM2->>SMO: Metering information
+    A2->>A2: Meter reading
+  
+```
+
+Sequence diagram for Scenario IV: Tariff configuration. The diagram shows interactions between Smart meter 1, Appliance 1, Smart metering operator, Smart meter 2, and Appliance 2. The process starts with the Smart metering operator sending 'Schedule information' to both Smart meter 1 and Smart meter 2. Each smart meter then performs a self-action 'Setting schedule for measurement'. Smart meter 1 sends 'Metering information' to the Smart metering operator, while Appliance 1 performs a self-action 'Meter reading'. Similarly, Smart meter 2 sends 'Metering information' to the Smart metering operator, while Appliance 2 performs a self-action 'Meter reading'. The Smart metering operator then sends 'Price of electricity changes' to both smart meters. Each smart meter performs a self-action 'Price of electricity changes' and then sends a 'Control message with the changed price information' to the Smart metering operator. The Smart metering operator then sends 'Control message with the changed price information' to both smart meters. Each smart meter performs a self-action 'Display the cost of electricity changes and new price applied'. Finally, each smart meter sends 'Metering information' to the Smart metering operator, while each appliance performs a self-action 'Meter reading'.
+
+F.747.1(12)\_F07
+
+**Figure 7 – Scenario IV: Tariff configuration**
+
+### 7.5 Scenario V: Meter reading data aggregation
+
+This scenario describes the procedures of how meter reading data, obtained at scheduled intervals by smart meters, are collected at an aggregating smart meter (or at an aggregating smart metering gateway) and then delivered to metering operators.
+
+- 1) A smart metering operator sends the smart meters a message to request aggregated metering data.
+- 2) Smart meters are configured to obtain meter reading data.
+- 3) According to the schedule, smart meters measure energy consumption and obtain meter reading data from home appliances.
+- 4) The obtained meter reading data are collected in an aggregating smart meter (or aggregating smart metering gateway). This is represented by Smart meter 2 in Figure 8.
+- 5) Finally, meter reading data are transferred to a smart metering operator.
+
+![Sequence diagram for Scenario V: Meter reading aggregation. The diagram shows interactions between Smart meter 1, Appliance 1, Smart meter 2, Appliance 2, and Smart metering operator. The process starts with the Smart metering operator sending 'Schedule and task information' to both Smart meter 1 and Smart meter 2. Each smart meter then performs a self-action 'Setting schedule for measurement'. Smart meter 1 sends 'Meter reading' to Appliance 1, which then sends 'Metering information' to Smart meter 1. Smart meter 2 sends 'Meter reading' to Appliance 2, which then sends 'Metering information' to Smart meter 2. Smart meter 2 performs a self-action 'Data aggregation' and sends 'Aggregated metering information' to the Smart metering operator. Smart meter 1 sends 'Meter reading' to Appliance 1, which then sends 'Metering information' to Smart meter 1. Smart meter 1 performs a self-action 'Data aggregation' and sends 'Aggregated metering information' to the Smart metering operator. The diagram is labeled F.747.1(12)_F08.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+```
+
+sequenceDiagram
+    participant S1 as Smart meter 1
+    participant A1 as Appliance 1
+    participant S2 as Smart meter 2
+    participant A2 as Appliance 2
+    participant SMO as Smart metering operator
+
+    SMO->>S1: Schedule and task information
+    SMO->>S2: Schedule and task information
+    S1->>S1: Setting schedule for measurement
+    S2->>S2: Setting schedule for measurement
+    S1->>A1: Meter reading
+    A1->>S1: Metering information
+    S2->>A2: Meter reading
+    A2->>S2: Metering information
+    S2->>S2: Data aggregation
+    S2->>SMO: Aggregated metering information
+    S1->>A1: Meter reading
+    A1->>S1: Metering information
+    S1->>S1: Data aggregation
+    S1->>SMO: Aggregated metering information
+  
+```
+
+Sequence diagram for Scenario V: Meter reading aggregation. The diagram shows interactions between Smart meter 1, Appliance 1, Smart meter 2, Appliance 2, and Smart metering operator. The process starts with the Smart metering operator sending 'Schedule and task information' to both Smart meter 1 and Smart meter 2. Each smart meter then performs a self-action 'Setting schedule for measurement'. Smart meter 1 sends 'Meter reading' to Appliance 1, which then sends 'Metering information' to Smart meter 1. Smart meter 2 sends 'Meter reading' to Appliance 2, which then sends 'Metering information' to Smart meter 2. Smart meter 2 performs a self-action 'Data aggregation' and sends 'Aggregated metering information' to the Smart metering operator. Smart meter 1 sends 'Meter reading' to Appliance 1, which then sends 'Metering information' to Smart meter 1. Smart meter 1 performs a self-action 'Data aggregation' and sends 'Aggregated metering information' to the Smart metering operator. The diagram is labeled F.747.1(12)\_F08.
+
+**Figure 8 – Scenario V: Meter reading aggregation**
+
+## 8 Network and USN requirements for smart metering services
+
+This clause specifies the sub-set of smart metering service requirements that relate to sensor networks and USNs.
+
+### 8.1 Time synchronization
+
+In smart metering services, exchanged data uses time stamps between smart meters and the systems of smart metering operators. Therefore, accurate and secure time synchronization should be supported in smart metering systems.
+
+### 8.2 Reliable information delivery
+
+In smart metering services, meter reading data can be frequently transferred from distributed meters, and also operators can send many control messages to smart meters. If delivery has failed, the operators cannot collect all of the meter reading data from smart meters. Therefore, smart metering services are required to provide reliable information delivery, such as meter reading data and control messages described in the scenarios of clause 7.
+
+### 8.3 Minimal time delay
+
+In the case of on-demand remote meter reading, a meter reading request and response should be delivered to the requesting entity with a minimal time delay.
+
+### 8.4 Real-time delivery of meter reading data
+
+The demands of smart metering operators require real-time responses of interconnected consumer premises equipment. Additionally, meter reading data are required to arrive at the metering operators in real-time (e.g., step 3 of scenarios I and II). Smart metering services are required to guarantee real-time data exchange.
+
+### **8.5 Bidirectional communication between meters and operators**
+
+Meter reading data are delivered from smart meters to smart metering operators as shown in step 3 of scenarios I and II, and step 2 of Scenario III. Control messages are also sent to and from the operators and the smart meters (e.g., in step 5 of Scenario III and step 3 of Scenario IV). In order to achieve this, smart metering services are required to support bidirectional communication between meters and operators.
+
+### **8.6 Security support including the authorization of operator and data confidentiality**
+
+Operators need to control meters so that the meters take action in accordance with their instructions. In this case, the operators should be authorized by smart meters to take actions to secure against unauthorized access (step 2 of Scenario II).
+
+As metering information may include personal information, it should not be revealed to unauthenticated third parties. Therefore, it is required to secure metering information from access by unauthenticated third parties as well as to support the integrity check of the data exchanged.
+
+### **8.7 Authentication of smart meters**
+
+Smart meters should be authenticated by smart metering applications. Authentication of smart metering devices can be achieved directly by smart metering applications, or by the authenticated smart metering gateways.
+
+### **8.8 Meter reading data processing**
+
+Both operators and smart meters should be able to perform data processing on meter reading, such as filtering, validation and aggregation. In some cases, data mining processing is necessary, for example, analysing patterns and predicting some events.
+
+### **8.9 Monitoring and management of smart meters**
+
+Smart meters or smart metering gateways should be monitored proactively in order to attempt to prevent and to correct errors. In addition, the following management capabilities should be supported from the network side:
+
+- secure software and firmware provisioning
+- configuration management
+- auto-configuration functions for smart meter area networks
+
+During the operation of smart metering services, smart metering applications should be able to specify a regular reporting schedule (Scenario I) for specific parameters and specific metering devices. Also, smart metering applications should be able to modify the value of the requested time period. Smart metering applications should be able to change the tariff configuration of smart meters when needed.
+
+## **9 USN capabilities for smart metering services**
+
+### **9.1 Time synchronization**
+
+USN is required to support accurate and secure time synchronization among sensor nodes, sensor network gateways and smart metering applications.
+
+### **9.2 Reliable transmission**
+
+Smart metering requires reliability of metering information delivery to ensure correct results. Therefore, a USN is recommended to guarantee the reliable transmission of measurement data and message delivery.
+
+### **9.3 Scalability**
+
+New smart meters (sensor nodes) can be added to, or one of the existing meters (sensor nodes) can be removed from an existing smart metering group (sensor networks). Such a change should not degrade the performance of the smart metering service. Therefore, sensor networks in USNs are required to support scalability.
+
+### **9.4 Mobility support**
+
+In some cases, a consumer can change the location of home appliances. This change may require changes in a meters' position in the intra-sensor network or inter-sensor networks. Therefore, sensor networks in USNs are recommended to support the mobility of smart meters (sensor nodes).
+
+### **9.5 Delivery latency**
+
+Meter reading data should be delivered with a minimal time delay or within a pre-set time. Therefore, a USN is recommended to guarantee data delivery with a minimal time delay or within a pre-set time.
+
+### **9.6 Fault detection and recovery**
+
+Link failure between wireless nodes is possible due to the characteristics of wireless transmission. Such failure can present negative effects on the reliability and delivery latency of smart metering services. A USN is recommended to detect link failures and recover from such failures.
+
+### **9.7 Security supporting confidentiality, integrity check, authorization and authentication**
+
+Meter reading data and messages may be transferred to/from operators and meters by hop-by-hop transmission amongst sensor nodes. Therefore, hop-by-hop security among sensor nodes is recommended to be implemented and a USN is recommended to provide an integrity check of the data exchanged. In addition, the USN is recommended to provide smart meters with authorization capabilities for access to smart meters of smart metering operators.
+
+Smart meters should be authenticated by smart metering applications directly, or through a smart metering gateway. Therefore, a USN is recommended to provide an authentication capability to smart metering applications for the authentication of smart meters (sensor nodes).
+
+### **9.8 Connectivity**
+
+Meter reading data, obtained from each sensor node, are collected by a gateway, and then the collected meter reading data are delivered to smart metering operators through transport networks. In addition, control messages of the operators are also delivered to each sensor node. In order to achieve this, it is recommended that connectivity be guaranteed amongst sensor nodes, between sensor nodes and the gateway, and between the gateway and outer networks.
+
+### **9.9 Unicasting and multicasting**
+
+A unicast networking service is required to be supported amongst sensor nodes so that meter reading data are delivered to smart metering operators. Furthermore, control messages of the metering operators should be delivered to all sensor nodes. Therefore, multicast networking support is also required.
+
+### **9.10 Data aggregation**
+
+Meter reading data from smart meters is collected and aggregated at a smart meter (sensor node) or at smart metering gateways, prior to data transfer to smart metering operators. Therefore, USN sensor nodes and gateways are required to support data aggregation.
+
+### **9.11 Distributed processing**
+
+If there are a number of smart meters (sensor nodes) in a smart home or building, a large number of meter reading data sets may be sent at the same time to a smart metering operator. To prevent node and service failure because of burst data centralization, distributed processing is required.
+
+### **9.12 Monitoring and management of sensor nodes**
+
+Smart meters (sensor nodes) or smart metering gateways (sensor network gateways) are recommended to be monitored and managed proactively in order to attempt to prevent and correct errors including secure software and firmware provisioning and configuration management, as well as, auto-configuration functions for sensor networks.
+
+Smart metering applications may also require a change of parameters in the smart meter for regularly scheduled reporting, as well as for changing tariff configuration. For satisfying this requirement, a USN is recommended to support the remote configuration setting and re-setting of sensor nodes acting as smart meters.
+
+## Bibliography
+
+- [b-ETSI TR 102 691] ETSI TR 102 691 v1.1.1 (2010), *Machine-to-Machine communications (M2M); Smart Metering Use Cases*.
+- [b-Khalifa] T. Khalifa, Naik, K. and Nayak, A. (2011), *A Survey of Communication Protocols for Automatic Meter Reading Applications*, Communications Surveys and Tutorials, Vol. 13, No. 2; pp.168-182, IEEE.
+- [b-NIST] NIST SP-1108 (2010), *Framework and Roadmap for Smart Grid Interoperability Standards*, Release 1.0, NIST.  
+<[http://www.nist.gov/public\\_affairs/releases/upload/smartgrid\\_interoperability\\_final.pdf](http://www.nist.gov/public_affairs/releases/upload/smartgrid_interoperability_final.pdf)>
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                             |
+|-----------------|---------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                           |
+| Series D        | General tariff principles                                                                   |
+| Series E        | Overall network operation, telephone service, service operation and human factors           |
+| <b>Series F</b> | <b>Non-telephone telecommunication services</b>                                             |
+| Series G        | Transmission systems and media, digital systems and networks                                |
+| Series H        | Audiovisual and multimedia systems                                                          |
+| Series I        | Integrated services digital network                                                         |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals |
+| Series K        | Protection against interference                                                             |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant     |
+| Series M        | Telecommunication management, including TMN and network maintenance                         |
+| Series N        | Maintenance: international sound programme and television transmission circuits             |
+| Series O        | Specifications of measuring equipment                                                       |
+| Series P        | Terminals and subjective and objective assessment methods                                   |
+| Series Q        | Switching and signalling                                                                    |
+| Series R        | Telegraph transmission                                                                      |
+| Series S        | Telegraph services terminal equipment                                                       |
+| Series T        | Terminals for telematic services                                                            |
+| Series U        | Telegraph switching                                                                         |
+| Series V        | Data communication over the telephone network                                               |
+| Series X        | Data networks, open system communications and security                                      |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks   |
+| Series Z        | Languages and general software aspects for telecommunication systems                        |

marked/Y/T-REC-Y.1231-200011-I_PDF-E/raw.md

@@ -0,0 +1,606 @@
+
+
+![ITU logo: a globe with the letters ITU inside, and a lightning bolt striking the globe.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: a globe with the letters ITU inside, and a lightning bolt striking the globe.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+# ITU-T
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# Y.1231
+
+(11/2000)
+
+SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE  
+AND INTERNET PROTOCOL ASPECTS
+
+Internet protocol aspects – Architecture, access, network  
+capabilities and resource management
+
+# --- **IP access network architecture**
+
+ITU-T Recommendation Y.1231
+
+(Formerly CCITT Recommendation)
+
+---
+
+## ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE AND INTERNET PROTOCOL ASPECTS
+
+|                                                                           |                      |
+|---------------------------------------------------------------------------|----------------------|
+| GLOBAL INFORMATION INFRASTRUCTURE                                         |                      |
+| General                                                                   | Y.100–Y.199          |
+| Services, applications and middleware                                     | Y.200–Y.299          |
+| Network aspects                                                           | Y.300–Y.399          |
+| Interfaces and protocols                                                  | Y.400–Y.499          |
+| Numbering, addressing and naming                                          | Y.500–Y.599          |
+| Operation, administration and maintenance                                 | Y.600–Y.699          |
+| Security                                                                  | Y.700–Y.799          |
+| Performances                                                              | Y.800–Y.899          |
+| INTERNET PROTOCOL ASPECTS                                                 |                      |
+| General                                                                   | Y.1000–Y.1099        |
+| Services and applications                                                 | Y.1100–Y.1199        |
+| <b>Architecture, access, network capabilities and resource management</b> | <b>Y.1200–Y.1299</b> |
+| Transport                                                                 | Y.1300–Y.1399        |
+| Interworking                                                              | Y.1400–Y.1499        |
+| Quality of service and network performance                                | Y.1500–Y.1599        |
+| Signalling                                                                | Y.1600–Y.1699        |
+| Operation, administration and maintenance                                 | Y.1700–Y.1799        |
+| Charging                                                                  | Y.1800–Y.1899        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **IP access network architecture**
+
+## **Summary**
+
+This Recommendation provides the definitions of terminology regarding IP access, and the high-level IP network architecture and models for the IP services. It describes the access types and interfaces to be supported by the IP access network, the IP access network capabilities and requirements, and the IP access network functional models and possible arrangements.
+
+###### **Source**
+
+ITU-T Recommendation Y.1231 was prepared by ITU-T Study Group 13 (2001-2004) and approved under the WTSA Resolution 1 procedure on 24 November 2000.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
+
+© ITU 2001
+
+All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU.
+
+## CONTENTS
+
+|                                                                     | <b>Page</b> |
+|---------------------------------------------------------------------|-------------|
+| 1 Scope.....                                                        | 1           |
+| 2 References.....                                                   | 1           |
+| 2.1 Normative references .....                                      | 1           |
+| 2.2 Informative references .....                                    | 2           |
+| 3 Definitions and abbreviations .....                               | 2           |
+| 3.1 Definitions .....                                               | 2           |
+| 3.2 Abbreviations.....                                              | 2           |
+| 4 Architectural model of IP access networks.....                    | 4           |
+| 4.1 General network architecture of IP network.....                 | 4           |
+| 4.2 IP access network reference model.....                          | 5           |
+| 5 Examples of functional models of IP Access Network.....           | 6           |
+| 5.1 Use of PPP .....                                                | 6           |
+| 5.1.1 PPP tunnelling aggregation.....                               | 7           |
+| 5.1.2 PPP terminated aggregation.....                               | 8           |
+| 5.2 Use of Ethernet .....                                           | 9           |
+| 6 Examples of access types and interfaces in IP access network..... | 10          |
+| 7 Examples of functional requirements for IP Access.....            | 10          |
+| Appendix I – Examples of IP mapping mechanisms .....                | 10          |
+| I.1 IP over PPP over ATM .....                                      | 10          |
+| I.2 IP over ATM.....                                                | 11          |
+| I.3 IP over Frame Relay.....                                        | 11          |
+| I.4 IP over PPP over PHY .....                                      | 11          |
+| I.5 IP over Ethernet .....                                          | 12          |
+| I.6 IP over PPP over Ethernet.....                                  | 12          |
+| Appendix II – An example of functional model of CATV access.....    | 13          |
+
+# **1 Scope**
+
+This Recommendation defines the functional IP Access Network architecture and the functions and requirements above the transport access functions defined in ITU-T Y.1001. The functional requirements for the Access Network Transport are defined for the handling and transport of digital bearer signals defined in ITU-T G.902.
+
+This Recommendation describes:
+
+- the definitions of terminology regarding IP access;
+- the high-level IP network architecture and models for the IP services;
+- the access types and interfaces to be supported by the IP access network;
+- the IP access network capabilities and requirements; and
+- the IP access network functional models and possible arrangements.
+
+The functional view of IP access network is independent of the access network transport functions described in ITU-T Y.1001.
+
+# **2 References**
+
+The following ITU-T Recommendations and other references contain provisions which, through references in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published.
+
+NOTE – A reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+## **2.1 Normative references**
+
+- [1] ITU-T Q.922 (1992), *ISDN data link layer specification for frame mode bearer services*.
+- [2] ITU-T I.363.5 (1996), *B-ISDN ATM Adaptation Layer specification: Type 5 AAL*.
+- [3] ITU-T I.414 (1997), *Overview of Recommendations on Layer 1 for ISDN and B-ISDN customer accesses*.
+- [4] ITU-T G.902 (1995), *Framework Recommendation on functional Access Networks (AN) – Architecture and functions, access types, management and service node aspects*.
+- [5] ITU-T Y.1001 (2000), *IP framework – A framework of convergence of telecommunications network and IP network technologies*.
+- [6] ITU-T Y.1401 (2000), *General requirements for interworking with Internet Protocol (IP)-based networks*.
+- [7] ISO/IEC 8802-2:1998, *Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 2: Logical link control*.
+
+## 2.2 Informative references
+
+- [8] IEEE Std 802.2 (1998), *Logical link control (802.2)*.
+- [9] IEEE Std 802.3 (1998), *CSMA/CD access method (802.3)*.
+- [10] Data-Over-Cable Service Interface Specifications, Cable Modem to Customer Premise Equipment Interface Specification, SP-CMCI-I03-991115, Cable Television Laboratories, Inc.
+- [11] IETF RFC 894 (1984), *A Standard for the Transmission of IP Datagrams over Ethernet Networks*.
+- [12] IETF RFC 1042 (1988), *A Standard for the Transmission of IP Datagrams over IEEE 802 Networks*.
+- [13] IETF RFC 1334 (1992), *Password Authentication Protocols*.
+- [14] IETF RFC 2684 (1999), *Multiprotocol Encapsulation over ATM Adaptation Layer 5*.
+- [15] IETF RFC 1661 (1994), *The Point-to-Point Protocol (PPP)*.
+- [16] IETF RFC 1662 (1994), *PPP in HDLC-like Framing*.
+- [17] IETF RFC 1994 (1996), *PPP Challenge Handshake Authentication Protocol (CHAP)*.
+- [18] IETF RFC 2138 (1997), *Remote Authentication Dial In User Services (RADIUS)*.
+- [19] IETF RFC 2225 (1998), *Classical IP and ARP over ATM*.
+- [20] IETF RFC 2364 (1998), *PPP over AAL5*.
+- [21] IETF RFC 2427 (1998), *Multiprotocol Interconnect over Frame Relay*.
+- [22] IETF RFC 2661 (1999), *Layer Two Tunnelling Protocol (L2TP)*.
+- [23] IETF RFC 2516 (1999), *A Method for Transmitting PPP Over Ethernet (PPPoE)*.
+
+# 3 Definitions and abbreviations
+
+## 3.1 Definitions
+
+This Recommendation defines the following terms:
+
+**3.1.1 IP access network:** An implementation comprising network entities to provide the required access capabilities between an "IP user" and an "IP service provider" for the provision of IP services. "IP user" and "IP service provider" are logical entities which terminate the IP layer and/or IP related functions, and may also include lower layer functions, and may also include lower layer functions.
+
+**3.1.2 IP core network:** IP service provider's network, including one or more IP service providers.
+
+## 3.2 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+|      |                                              |
+|------|----------------------------------------------|
+| AAA  | Authentication, Authorization and Accounting |
+| AF   | Access Function                              |
+| ARP  | Address Resolution Protocol                  |
+| ATM  | Asynchronous Transfer Mode                   |
+| CHAP | Challenge Handshake Authentication Protocol  |
+| CMCI | Cable Modem to CPE Interface                 |
+
+|        |                                                  |
+|--------|--------------------------------------------------|
+| CMTS   | Cable Modem Termination System                   |
+| CPE    | Customer Premises Equipment                      |
+| CPN    | Customer Premises Network                        |
+| DHCP   | Dynamic Host Configuration Protocol              |
+| DIX    | Digital Intel Xerox                              |
+| DOCSIS | Data-Over-Cable Service Interface Specifications |
+| EF     | Edge Function                                    |
+| FR     | Frame Relay                                      |
+| HFC    | Hybrid Fibre and Coax                            |
+| IP     | Internet Protocol                                |
+| IPSEC  | Internet Protocol Security                       |
+| ISDN   | Integrated Services Digital Network              |
+| IWF    | InterWorking Function                            |
+| LAN    | Local Area Network                               |
+| LLC    | Logical Link Control                             |
+| L2TP   | Layer 2 Tunnelling Protocol                      |
+| MAC    | Medium Access Control                            |
+| MPLS   | Multiprotocol Label Switching                    |
+| NAT    | Network Address Translation                      |
+| NSI    | Network Side Interface                           |
+| NT     | Network Termination                              |
+| PAP    | Password Authentication Protocol                 |
+| PC     | Personal Computer                                |
+| PCI    | Peripheral Component Interface                   |
+| PHY    | Physical Layer                                   |
+| PON    | Passive Optical Network                          |
+| PPP    | Point-to-Point Protocol                          |
+| PSTN   | Public Switched Telephone Network                |
+| RADIUS | Remote Access Dial In User Services              |
+| RFI    | Radio Frequency Interface                        |
+| RP     | Reference Point                                  |
+| SNMP   | Simple Network Management Protocol               |
+| TE     | Terminal Equipment                               |
+| TEL    | Telephone                                        |
+| TFTP   | Trivial File Transfer Protocol                   |
+| UDP    | User Datagram Protocol                           |
+| VCI    | Virtual Channel Identifier                       |
+
+VPI        Virtual Path Identifier  
+WAN       Wide Area Network
+
+# 4 Architectural model of IP access networks
+
+## 4.1 General network architecture of IP network
+
+Figure 1a shows a general network architecture of IP network. In Figure 1a, the lines between various rectangles and ellipses represent connections that are bidirectional, that may be asymmetrical in bit rate, and that may be of differing media in the two directions. The reference points (RP) illustrated are logical separation between the functions and may not correspond to physical interfaces in certain network implementations. In certain network implementations, access and core networks may not be separable.
+
+![Figure 1a: General network architecture of IP network. The diagram shows a symmetrical architecture. On the left, a group of three rectangles labeled 'TE', 'PC', and 'TEL' is connected to a large oval. Below this oval is a bracket labeled 'CPN'. This oval is connected to an oval labeled 'IP Access Network'. A dashed line labeled 'RP' separates the 'IP Access Network' from an oval labeled 'IP Core Network'. Another dashed line labeled 'RP' separates the 'IP Core Network' from a second oval labeled 'IP Access Network'. This second 'IP Access Network' is connected to another large oval, which is in turn connected to a group of three rectangles labeled 'TE', 'PC', and 'TEL'. Below this oval is a bracket labeled 'CPN'. The entire structure is symmetrical around the central 'IP Core Network'.](7a0db9703b68b3d06cdaeefc084c0006_img.jpg)
+
+T1317460-00
+
+Figure 1a: General network architecture of IP network. The diagram shows a symmetrical architecture. On the left, a group of three rectangles labeled 'TE', 'PC', and 'TEL' is connected to a large oval. Below this oval is a bracket labeled 'CPN'. This oval is connected to an oval labeled 'IP Access Network'. A dashed line labeled 'RP' separates the 'IP Access Network' from an oval labeled 'IP Core Network'. Another dashed line labeled 'RP' separates the 'IP Core Network' from a second oval labeled 'IP Access Network'. This second 'IP Access Network' is connected to another large oval, which is in turn connected to a group of three rectangles labeled 'TE', 'PC', and 'TEL'. Below this oval is a bracket labeled 'CPN'. The entire structure is symmetrical around the central 'IP Core Network'.
+
+**Figure 1a/Y.1231 – General network architecture of IP network**
+
+Figure 1b shows an example of relationship between IP network and PSTN/ISDN. In Figure 1b, some connections and InterWorking Function (IWF) between IP Access/Core network and PSTN/ISDN are shown as an example, but not all PSTN/ISDN connections may be necessary. A definition of IWF is described in ITU-T Y.1401 [6].
+
+![Figure 1b/Y.1231: An example of relationship between IP network and PSTN/ISDN. The diagram shows a central PSTN/ISDN oval at the top. Below it are three IWF (Interworking Function) boxes, each connected to the PSTN/ISDN. These IWFs connect to three IP Access Network ovals, which are connected to an IP Core Network oval. The IP Access Networks are connected to three CPN (Customer Premises Network) ovals. Each CPN contains a TEL (Telephone) box, a PC (Personal Computer) box, and a TE (Terminal Equipment) box. The connections between the IP Access Networks and the IP Core Network are labeled RP (Residual Port).](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+T1317470-00
+
+Figure 1b/Y.1231: An example of relationship between IP network and PSTN/ISDN. The diagram shows a central PSTN/ISDN oval at the top. Below it are three IWF (Interworking Function) boxes, each connected to the PSTN/ISDN. These IWFs connect to three IP Access Network ovals, which are connected to an IP Core Network oval. The IP Access Networks are connected to three CPN (Customer Premises Network) ovals. Each CPN contains a TEL (Telephone) box, a PC (Personal Computer) box, and a TE (Terminal Equipment) box. The connections between the IP Access Networks and the IP Core Network are labeled RP (Residual Port).
+
+**Figure 1b/Y.1231 – An example of relationship between IP network and PSTN/ISDN**
+
+## 4.2 IP access network reference model
+
+Figure 2 shows an example of IP access network reference model. In some cases, the IP access Function (IP-AF) can be distributed within the IP Access Network. Examples of the IP-AF are described in clause 7.
+
+The functional requirements for the Access Network Transport are defined for the handling and transport of digital bearer signals defined in ITU-T G.902 [4].
+
+The functional view of IP access network is independent of the access network transport functions described in ITU-T Y.1001 [5].
+
+![Figure 2/Y.1231: IP Access Network architecture example. The diagram shows a central IP Access Network box. Inside this box are three stacked components: IP Access Network System Management (top), IP Access Function (middle), and Access Network Transport Function (bottom). A dashed line labeled 'RP' for management interface connects the top of the IP Access Network box to a management interface. The IP Access Network box is connected to a CPN (Customer Premises Network) oval on the left and an IP Core Network oval on the right. The connections are labeled RP. The IP Core Network contains three stacked ovals: IP Service Provider 1, IP Service Provider 2, and IP Service Provider 3. A double-headed arrow at the bottom indicates the IP Access Network span.](053f1077d592e6622cd21dc4bb4cb366_img.jpg)
+
+T1317480-00
+
+Figure 2/Y.1231: IP Access Network architecture example. The diagram shows a central IP Access Network box. Inside this box are three stacked components: IP Access Network System Management (top), IP Access Function (middle), and Access Network Transport Function (bottom). A dashed line labeled 'RP' for management interface connects the top of the IP Access Network box to a management interface. The IP Access Network box is connected to a CPN (Customer Premises Network) oval on the left and an IP Core Network oval on the right. The connections are labeled RP. The IP Core Network contains three stacked ovals: IP Service Provider 1, IP Service Provider 2, and IP Service Provider 3. A double-headed arrow at the bottom indicates the IP Access Network span.
+
+**Figure 2/Y.1231 – IP Access Network architecture example**
+
+# 5 Examples of functional models of IP Access Network
+
+## 5.1 Use of PPP
+
+In this clause, PPP is shown as an example for protocol used to carry IP over access network. PPP is a widely used protocol for dial-up IP access and ADSL access. PPP termination point in the network side interacts with AAA (Authentication, Authorization and Accounting) server (e.g. RADIUS server) and provides AAA functions.
+
+Figures 3a and 3b provide the following two options regarding PPP termination point in the network side:
+
+- 1) PPP tunnelling aggregation (PPP is terminated by IP service provider); and
+- 2) PPP terminated aggregation (PPP is terminated by the IP access function).
+
+![Figure 3a: PPP tunnelling aggregation architecture diagram.](7e670a2b556b53ea9002dfff3a420e08_img.jpg)
+
+The diagram illustrates the PPP tunnelling aggregation architecture. It consists of three main components: IP User, IP Access Function, and IP Service Provider. The IP User contains a PPP Termination Function. The IP Access Function is a central box. The IP Service Provider contains a PPP Termination Function, an AAA Client Function, and an AAA Server Function. A horizontal line connects the PPP Termination Function in the IP User to the PPP Termination Function in the IP Service Provider. The IP Access Function is positioned between them, with a vertical line connecting the PPP Termination Function in the IP Service Provider to the AAA Client Function, which in turn connects to the AAA Server Function.
+
+T1317490-00
+
+Figure 3a: PPP tunnelling aggregation architecture diagram.
+
+**Figure 3a/Y.1231 – PPP tunnelling aggregation**
+
+![Figure 3b: PPP terminated aggregation architecture diagram.](8e14350b4b669119a3bdfca7869110ca_img.jpg)
+
+The diagram illustrates the PPP terminated aggregation architecture. It consists of three main components: IP User, IP Access Function, and IP Service Provider. The IP User contains a PPP box. The IP Access Function contains a PPP box and an AAA Client box. The IP Service Provider is an empty box. A horizontal line connects the PPP box in the IP User to the PPP box in the IP Access Function. Another horizontal line connects the PPP box in the IP Access Function to the IP Service Provider. A vertical line connects the AAA Client box in the IP Access Function to an AAA Server box below it.
+
+T1317500-00
+
+Figure 3b: PPP terminated aggregation architecture diagram.
+
+**Figure 3b/Y.1231 – PPP terminated aggregation**
+
+### 5.1.1 PPP tunnelling aggregation
+
+This clause gives some examples of protocol stacks for the PPP tunnelling aggregation. In this case, "IP user" directly accesses the "IP service provider". Several transport systems can be cascaded without IP and PPP processing in the access network.
+
+#### Case 1) Layer 2 multiplexing in IP access network (e.g. direct IP access)
+
+This is a case that only Layer 2 multiplexing transport function such as ATM or FR are supported in IP access network. This functional model is shown in Figure 4.
+
+![Figure 4: Functional model of Layer 2 multiplexing. The diagram shows three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has IP, PPP, and PHY layers. The IP Access Function stack has a PHY layer and a diagonal section labeled 'ATM, FR etc.'. The IP Service Provider stack has IP, PPP, ATM, FR etc., and PHY layers. Arrows indicate connections: IP to IP, PPP to PPP, and PHY to PHY. The IP Access Function's PHY layer connects to the IP User's PHY layer and the IP Service Provider's PHY layer.](1439cb942d9e363bbb3161b5540dd8c6_img.jpg)
+
+Figure 4: Functional model of Layer 2 multiplexing. The diagram shows three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has IP, PPP, and PHY layers. The IP Access Function stack has a PHY layer and a diagonal section labeled 'ATM, FR etc.'. The IP Service Provider stack has IP, PPP, ATM, FR etc., and PHY layers. Arrows indicate connections: IP to IP, PPP to PPP, and PHY to PHY. The IP Access Function's PHY layer connects to the IP User's PHY layer and the IP Service Provider's PHY layer.
+
+T1317510-00
+
+**Figure 4/Y.1231 – Functional model of Layer 2 multiplexing**
+
+#### Case 2) PPP tunnelling (e.g. L2TP [22])
+
+This is a case that L2TP function is used in IP access network. This functional model is shown in Figure 5.
+
+![Figure 5: Functional model of PPP tunnelling. The diagram shows three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has IP, PPP, and PHY layers. The IP Access Function stack has a PHY layer, a diagonal section labeled 'L2TP', and an IP (Note) layer. The IP Service Provider stack has IP, PPP, L2TP, IP (Note), ATM, FR etc., and PHY layers. Arrows indicate connections: IP to IP, PPP to PPP, L2TP to L2TP, IP (Note) to IP (Note), and PHY to PHY. The IP Access Function's PHY layer connects to the IP User's PHY layer and the IP Service Provider's PHY layer.](fbfa653853daf5541118a9ddecb92284_img.jpg)
+
+Figure 5: Functional model of PPP tunnelling. The diagram shows three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has IP, PPP, and PHY layers. The IP Access Function stack has a PHY layer, a diagonal section labeled 'L2TP', and an IP (Note) layer. The IP Service Provider stack has IP, PPP, L2TP, IP (Note), ATM, FR etc., and PHY layers. Arrows indicate connections: IP to IP, PPP to PPP, L2TP to L2TP, IP (Note) to IP (Note), and PHY to PHY. The IP Access Function's PHY layer connects to the IP User's PHY layer and the IP Service Provider's PHY layer.
+
+T1317520-00
+
+NOTE – This IP layer provides a transport function between IP access function and IP service provider.
+
+**Figure 5/Y.1231 – Functional model of PPP tunnelling**
+
+### 5.1.2 PPP terminated aggregation
+
+This clause gives some examples of protocol stacks for the PPP terminated aggregation. In this case, PPP is terminated in IP access network.
+
+#### Case 1) IP tunnelling (e.g. IPSEC)
+
+This is a case that IP tunnelling is used in IP access network. This functional model is shown in Figure 6.
+
+![Figure 6: Functional model of IP tunnelling. The diagram shows three protocol stacks: IP User, IP Access Function, and IP Service Provider. The IP User stack has IP, PPP, and PHY layers. The IP Access Function stack is split into two paths: one with PPP and PHY layers, and another with IPSEC, IP (Note), ATM, FR etc., and PHY layers. The IP Service Provider stack has IP, IPSEC, IP (Note), ATM, FR etc., and PHY layers. Arrows indicate bidirectional communication between corresponding layers across the stacks. A reference code T1317530-00 is at the bottom right.](cab0834804fb031b43865554cc8d06ab_img.jpg)
+
+T1317530-00
+
+Figure 6: Functional model of IP tunnelling. The diagram shows three protocol stacks: IP User, IP Access Function, and IP Service Provider. The IP User stack has IP, PPP, and PHY layers. The IP Access Function stack is split into two paths: one with PPP and PHY layers, and another with IPSEC, IP (Note), ATM, FR etc., and PHY layers. The IP Service Provider stack has IP, IPSEC, IP (Note), ATM, FR etc., and PHY layers. Arrows indicate bidirectional communication between corresponding layers across the stacks. A reference code T1317530-00 is at the bottom right.
+
+NOTE – This IP layer provides a transport function between IP access function and IP service provider.
+
+**Figure 6/Y.1231 – Functional model of IP tunnelling**
+
+#### Case 2-1) Layer 3 routing (e.g. IP router)
+
+This is a case that IP handling function such as IP router exists in IP access network. This functional model is shown in Figure 7.
+
+![Figure 7: Functional model of L3 routing. The diagram shows three protocol stacks: IP User, IP Access Function, and IP Service Provider. The IP User stack has IP, PPP, and PHY layers. The IP Access Function stack is split into two paths: one with IP and PHY layers, and another with PPP, ATM, FR etc., and PHY layers. The IP Service Provider stack has IP, ATM, FR etc., and PHY layers. Arrows indicate bidirectional communication between corresponding layers across the stacks. A reference code T1317540-00 is at the bottom right.](e9d825d87c5f85c8dba0664eace96ef4_img.jpg)
+
+T1317540-00
+
+Figure 7: Functional model of L3 routing. The diagram shows three protocol stacks: IP User, IP Access Function, and IP Service Provider. The IP User stack has IP, PPP, and PHY layers. The IP Access Function stack is split into two paths: one with IP and PHY layers, and another with PPP, ATM, FR etc., and PHY layers. The IP Service Provider stack has IP, ATM, FR etc., and PHY layers. Arrows indicate bidirectional communication between corresponding layers across the stacks. A reference code T1317540-00 is at the bottom right.
+
+**Figure 7/Y.1231 – Functional model of L3 routing**
+
+#### Case 2-2) Virtual router
+
+This is also a case that IP handling function exists in IP access network. This functional model is shown in Figure 8.
+
+![Figure 8/Y.1231 – Functional model of virtual router. This diagram shows the functional model of a virtual router. It consists of three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has three layers: IP, PPP, and PHY. The IP Access Function stack is divided into two parts: a left part with IP, PPP, and PHY layers, and a right part with IP, ATM, FR etc., and PHY layers. The IP Service Provider stack has three layers: IP, ATM, FR etc., and PHY. Bidirectional arrows connect the IP layers of all three components. Bidirectional arrows connect the PPP layer of the IP User to the PPP layer of the IP Access Function. Bidirectional arrows connect the PHY layer of the IP User to the PHY layer of the IP Access Function. Bidirectional arrows connect the ATM, FR etc. layer of the IP Access Function to the ATM, FR etc. layer of the IP Service Provider. Bidirectional arrows connect the PHY layer of the IP Access Function to the PHY layer of the IP Service Provider. A label 'Multiple instances of IP routing tables for each virtual router' points to the IP layer of the IP Access Function.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+T1317550-00
+
+Figure 8/Y.1231 – Functional model of virtual router. This diagram shows the functional model of a virtual router. It consists of three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has three layers: IP, PPP, and PHY. The IP Access Function stack is divided into two parts: a left part with IP, PPP, and PHY layers, and a right part with IP, ATM, FR etc., and PHY layers. The IP Service Provider stack has three layers: IP, ATM, FR etc., and PHY. Bidirectional arrows connect the IP layers of all three components. Bidirectional arrows connect the PPP layer of the IP User to the PPP layer of the IP Access Function. Bidirectional arrows connect the PHY layer of the IP User to the PHY layer of the IP Access Function. Bidirectional arrows connect the ATM, FR etc. layer of the IP Access Function to the ATM, FR etc. layer of the IP Service Provider. Bidirectional arrows connect the PHY layer of the IP Access Function to the PHY layer of the IP Service Provider. A label 'Multiple instances of IP routing tables for each virtual router' points to the IP layer of the IP Access Function.
+
+**Figure 8/Y.1231 – Functional model of virtual router**
+
+#### Case 3) MPLS (multiprotocol label switching)
+
+This is a case that IP transport function is translated by the lower layer such as ATM in IP access network. This functional model is shown in Figure 9. There is a case that "Label" stack is null in the user-plane, when the ATM VPI/VCIs are used as MPLS labels.
+
+![Figure 9/Y.1231 – Functional model of MPLS. This diagram shows the functional model of MPLS. It consists of three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has three layers: IP, PPP, and PHY. The IP Access Function stack is divided into two parts: a left part with PPP and PHY layers, and a right part with Label, ATM, SDH etc., and PHY layers. The IP Service Provider stack has four layers: IP, Label, ATM, SDH etc., and PHY. Bidirectional arrows connect the IP layers of all three components. Bidirectional arrows connect the PPP layer of the IP User to the PPP layer of the IP Access Function. Bidirectional arrows connect the PHY layer of the IP User to the PHY layer of the IP Access Function. Bidirectional arrows connect the Label layer of the IP Access Function to the Label layer of the IP Service Provider. Bidirectional arrows connect the ATM, SDH etc. layer of the IP Access Function to the ATM, SDH etc. layer of the IP Service Provider. Bidirectional arrows connect the PHY layer of the IP Access Function to the PHY layer of the IP Service Provider.](bd671b21db63e6fdb2196e9b18502aac_img.jpg)
+
+T1317560-00
+
+Figure 9/Y.1231 – Functional model of MPLS. This diagram shows the functional model of MPLS. It consists of three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has three layers: IP, PPP, and PHY. The IP Access Function stack is divided into two parts: a left part with PPP and PHY layers, and a right part with Label, ATM, SDH etc., and PHY layers. The IP Service Provider stack has four layers: IP, Label, ATM, SDH etc., and PHY. Bidirectional arrows connect the IP layers of all three components. Bidirectional arrows connect the PPP layer of the IP User to the PPP layer of the IP Access Function. Bidirectional arrows connect the PHY layer of the IP User to the PHY layer of the IP Access Function. Bidirectional arrows connect the Label layer of the IP Access Function to the Label layer of the IP Service Provider. Bidirectional arrows connect the ATM, SDH etc. layer of the IP Access Function to the ATM, SDH etc. layer of the IP Service Provider. Bidirectional arrows connect the PHY layer of the IP Access Function to the PHY layer of the IP Service Provider.
+
+**Figure 9/Y.1231 – Functional model of MPLS**
+
+## 5.2 Use of Ethernet
+
+In this clause, Ethernet is an example of protocol used to carry IP over access network. Figure 10 shows examples of protocol stacks of Ethernet access.
+
+![Figure 10/Y.1231 – Functional model of Ethernet use. This diagram shows the functional model of Ethernet use. It consists of three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has three layers: IP, Ethernet, and PHY. The IP Access Function stack is divided into two parts: a left part with IP, Ethernet, and PHY layers, and a right part with IP, ATM, FR etc., and PHY layers. The IP Service Provider stack has three layers: IP, ATM, FR etc., and PHY. Bidirectional arrows connect the IP layers of all three components. Bidirectional arrows connect the Ethernet layer of the IP User to the Ethernet layer of the IP Access Function. Bidirectional arrows connect the PHY layer of the IP User to the PHY layer of the IP Access Function. Bidirectional arrows connect the ATM, FR etc. layer of the IP Access Function to the ATM, FR etc. layer of the IP Service Provider. Bidirectional arrows connect the PHY layer of the IP Access Function to the PHY layer of the IP Service Provider.](f6e8acf9f931452d01688d311b5c0364_img.jpg)
+
+T1317570-00
+
+Figure 10/Y.1231 – Functional model of Ethernet use. This diagram shows the functional model of Ethernet use. It consists of three main components: IP User, IP Access Function, and IP Service Provider. The IP User stack has three layers: IP, Ethernet, and PHY. The IP Access Function stack is divided into two parts: a left part with IP, Ethernet, and PHY layers, and a right part with IP, ATM, FR etc., and PHY layers. The IP Service Provider stack has three layers: IP, ATM, FR etc., and PHY. Bidirectional arrows connect the IP layers of all three components. Bidirectional arrows connect the Ethernet layer of the IP User to the Ethernet layer of the IP Access Function. Bidirectional arrows connect the PHY layer of the IP User to the PHY layer of the IP Access Function. Bidirectional arrows connect the ATM, FR etc. layer of the IP Access Function to the ATM, FR etc. layer of the IP Service Provider. Bidirectional arrows connect the PHY layer of the IP Access Function to the PHY layer of the IP Service Provider.
+
+**Figure 10/Y.1231 – Functional model of Ethernet use**
+
+# 6 Examples of access types and interfaces in IP access network
+
+Possible transmission mechanisms for user access are shown as follows:
+
+- ISDN:
+  - Basic rate access (B/2B/D channel);
+  - Primary rate (1544 kbit/s, 2048 kbit/s).
+- B-ISDN access (1544 kbit/s-622 080 kbit/s).
+- xDSL.
+- Wireless and Satellite.
+- PON, SDV, HFC and other optical systems.
+- CATV access.
+- LAN/WAN.
+
+Examples of IP mapping mechanisms on each transmission system are shown in Appendix I.
+
+An example of functional architecture of CATV access is shown in Appendix II.
+
+Further examples and overview are described in ITU-T I.414 [3].
+
+# 7 Examples of functional requirements for IP Access
+
+Possible IP access functions are as follows:
+
+- Dynamic selection of multiple IP service providers.
+- Dynamic allocation of IP address using PPP.
+- NAT.
+- Authentication (PAP [13], CHAP [17]).
+- Encryption.
+- Billing usage metering and interaction with RADIUS [18] server.
+
+# APPENDIX I
+
+## Examples of IP mapping mechanisms
+
+The following diagrams show protocol stacks for IP on various transmission systems. The detailed mapping mechanisms are described in the referenced documents.
+
+### I.1 IP over PPP over ATM
+
+Figure I.1 shows IP over PPP over ATM mapping mechanism which is defined in IETF RFC 2364, "PPP over AAL5" [20].
+
+|                      |                               |
+|----------------------|-------------------------------|
+| IP                   |                               |
+| PPP                  | (IETF RFC 1661/IETF RFC 2364) |
+| Encapsulation Header | (IETF RFC 2684)               |
+| AAL5                 | (ITU-T I.363.5)               |
+| ATM                  |                               |
+| PHY                  |                               |
+
+**Figure I.1/Y.1231 – Mapping mechanism for IP over PPP over ATM**
+
+### I.2 IP over ATM
+
+Figure I.2 shows IP over ATM mapping mechanism which is defined in IETF RFC 2225, "Classical IP and ARP over ATM" [19].
+
+|                      |                 |
+|----------------------|-----------------|
+| IP                   | (IETF RFC 2225) |
+| Encapsulation Header | (IETF RFC 2684) |
+| AAL5                 | (ITU-T I.363.5) |
+| ATM                  |                 |
+| PHY                  |                 |
+
+**Figure I.2/Y.1231 – Mapping mechanism  
+for IP over ATM**
+
+### I.3 IP over Frame Relay
+
+Figure I.3 shows IP over FR mapping mechanism which is defined in IETF RFC 2427, "Multiprotocol Interconnect over Frame Relay" [21].
+
+|                      |                 |
+|----------------------|-----------------|
+| IP                   |                 |
+| Encapsulation Header | (IETF RFC 2427) |
+| LAPF                 | (ITU-T Q.922)   |
+| PHY                  |                 |
+
+**Figure I.3/Y.1231 – Mapping mechanism  
+for IP over FR**
+
+### I.4 IP over PPP over PHY
+
+Figure I.4 shows PPP directly mapping to physical layer (e.g. ISDN, SDH).
+
+|     |                               |
+|-----|-------------------------------|
+| IP  |                               |
+| PPP | (IETF RFC 1661/IETF RFC 1662) |
+| PHY |                               |
+
+**Figure I.4/Y.1231 – Mapping mechanism  
+for IP over PPP**
+
+NOTE – Other mapping mechanisms may be used, for example to support the requirements of radio systems such as satellite systems.
+
+### I.5 IP over Ethernet
+
+Two types of Ethernet are commonly used. Two types of IP over Ethernet mapping mechanism are defined in separate IETF documents (IETF RFC 894 [11] and IETF RFC 1042 [12]).
+
+Figure I.5 shows IP mapping mechanism using Ethernet (IEEE 802.3 [9]/ISO/IEC 8802-2 [7]) and Figure I.6 shows IP mapping mechanism using Ethernet (IEEE 802.3 [9]/ISO/IEC 8802-2 [7]) with LLC.
+
+|     |                             |
+|-----|-----------------------------|
+| IP  | (IETF RFC 894)              |
+| MAC | (IEEE 802.3/ISO/IEC 8802-2) |
+| PHY |                             |
+
+**Figure I.5/Y.1231 – Mapping mechanism for IP over Ethernet (IEEE 802.3/ISO/IEC 8802-2)**
+
+|     |                             |
+|-----|-----------------------------|
+| IP  | (IETF RFC 1042)             |
+| LLC | (IEEE 802.2)                |
+| MAC | (IEEE 802.3/ISO/IEC 8802-2) |
+| PHY |                             |
+
+**Figure I.6/Y.1231 – Mapping mechanism for IP over Ethernet (IEEE 802.3/ISO/IEC 8802-2) with LLC**
+
+### I.6 IP over PPP over Ethernet
+
+Figure I.7 shows IP over PPP over Ethernet mapping mechanism which is defined in IETF document (IETF RFC 2516 [23]).
+
+|                    |                               |
+|--------------------|-------------------------------|
+| IP                 |                               |
+| PPP                | (IETF RFC 1661/IETF RFC 1662) |
+| Encapsulation Head | (IETF RFC 2516)               |
+| MAC                | (IEEE 802.3/ISO/IEC 8802-2)   |
+| PHY                |                               |
+
+**Figure I.7/Y.1231 – Mapping mechanism for IP over PPP over Ethernet**
+
+# APPENDIX II
+
+## An example of functional model of CATV access
+
+See Figure II.1.
+
+![Functional model of CATV access diagram showing CMTS, PCI Cable Modem, and Host CPE components and their interconnections.](4356776ca004ecba5d599667a155d7d4_img.jpg)
+
+The diagram illustrates the functional model of CATV access, showing the interaction between three main components: CMTS, PCI Cable Modem, and Host CPE.
+
+**CMTS (Cable Modem Termination System):**
+
+- Layers: DHCP, TFTP, SNMP, Security Magmt, UDP, IP, ARP, Optional Router, Forwarder, DIX/802.2 LLC, DIX/802.3 MAC, DOCSIS Security, DOCSIS MAC, DOCSIS con-vergence, DOCSIS PHY.
+- Connections: Internet (via NSI Data Link and NSI PHY), RFI (via DOCSIS PHY).
+
+**PCI Cable Modem:**
+
+- Layers: DHCP, TFTP, SNMP, Security Magmt, UDP, IP, ARP, DIX/802.2 LLC, DIX/802.3 MAC, DIX/802.3 MAC filter, DOCSIS Security, DOCSIS MAC, DOCSIS con-vergence, DOCSIS PHY.
+- Connections: PCI PHY, PCI CMCI (to Host CPE).
+
+**Host CPE (Customer Premises Equipment):**
+
+- Layers: Internet Applications, services, and agents, UDP, IP, ARP, DIX/802.2 LLC, DIX/802.3 MAC, PCI PHY.
+- Connections: PCI CMCI (from PCI Cable Modem).
+
+**Interconnections:**
+
+- The CMTS connects to the Internet via NSI Data Link and NSI PHY.
+- The CMTS connects to the PCI Cable Modem via RFI (Radio Frequency Interface) through the DOCSIS PHY layer.
+- The PCI Cable Modem connects to the Host CPE via PCI CMCI (Cable Modem Control Interface).
+- The Host CPE connects to the PCI Cable Modem via PCI PHY (Physical Layer).
+
+Functional model of CATV access diagram showing CMTS, PCI Cable Modem, and Host CPE components and their interconnections.
+
+T1318100-01
+
+NOTE – This figure is extracted from Cable Television Laboratories, Inc.'s specification – Data-Over-Cable Service Interface Specifications (SP-CMCI-I03-991115 [10]) in order to give an example of Ethernet use to carry IP over the access network.
+
+**Figure II.1/Y.1231 – Functional model of CATV access**
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                |
+|-----------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                              |
+| Series B        | Means of expression: definitions, symbols, classification                                                                      |
+| Series C        | General telecommunication statistics                                                                                           |
+| Series D        | General tariff principles                                                                                                      |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                              |
+| Series F        | Non-telephone telecommunication services                                                                                       |
+| Series G        | Transmission systems and media, digital systems and networks                                                                   |
+| Series H        | Audiovisual and multimedia systems                                                                                             |
+| Series I        | Integrated services digital network                                                                                            |
+| Series J        | Transmission of television, sound programme and other multimedia signals                                                       |
+| Series K        | Protection against interference                                                                                                |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant                                        |
+| Series M        | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                |
+| Series O        | Specifications of measuring equipment                                                                                          |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                   |
+| Series Q        | Switching and signalling                                                                                                       |
+| Series R        | Telegraph transmission                                                                                                         |
+| Series S        | Telegraph services terminal equipment                                                                                          |
+| Series T        | Terminals for telematic services                                                                                               |
+| Series U        | Telegraph switching                                                                                                            |
+| Series V        | Data communication over the telephone network                                                                                  |
+| Series X        | Data networks and open system communications                                                                                   |
+| <b>Series Y</b> | <b>Global information infrastructure and Internet protocol aspects</b>                                                         |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                           |

marked/Y/T-REC-Y.1241-200103-I_PDF-E/raw.md

@@ -0,0 +1,640 @@
+
+
+![ITU logo: a globe with the letters ITU inside, and a lightning bolt striking the globe.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: a globe with the letters ITU inside, and a lightning bolt striking the globe.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**Y.1241**
+
+(03/2001)
+
+SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE  
+AND INTERNET PROTOCOL ASPECTS
+
+Internet protocol aspects – Architecture, access, network  
+capabilities and resource management
+
+# --- **Support of IP-based services using IP transfer capabilities**
+
+ITU-T Recommendation Y.1241
+
+(Formerly CCITT Recommendation)
+
+---
+
+## ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE AND INTERNET PROTOCOL ASPECTS
+
+|                                                                           |                      |
+|---------------------------------------------------------------------------|----------------------|
+| GLOBAL INFORMATION INFRASTRUCTURE                                         |                      |
+| General                                                                   | Y.100–Y.199          |
+| Services, applications and middleware                                     | Y.200–Y.299          |
+| Network aspects                                                           | Y.300–Y.399          |
+| Interfaces and protocols                                                  | Y.400–Y.499          |
+| Numbering, addressing and naming                                          | Y.500–Y.599          |
+| Operation, administration and maintenance                                 | Y.600–Y.699          |
+| Security                                                                  | Y.700–Y.799          |
+| Performances                                                              | Y.800–Y.899          |
+| INTERNET PROTOCOL ASPECTS                                                 |                      |
+| General                                                                   | Y.1000–Y.1099        |
+| Services and applications                                                 | Y.1100–Y.1199        |
+| <b>Architecture, access, network capabilities and resource management</b> | <b>Y.1200–Y.1299</b> |
+| Transport                                                                 | Y.1300–Y.1399        |
+| Interworking                                                              | Y.1400–Y.1499        |
+| Quality of service and network performance                                | Y.1500–Y.1599        |
+| Signalling                                                                | Y.1600–Y.1699        |
+| Operation, administration and maintenance                                 | Y.1700–Y.1799        |
+| Charging                                                                  | Y.1800–Y.1899        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **Support of IP-based services using IP transfer capabilities**
+
+## **Summary**
+
+This Recommendation classifies IP-based services, introduces the concept of the IP service plane and presents resulting IP transfer capability attributes. This Recommendation describes the service level agreement and identifies the range of SLA attributes to be considered.
+
+## **Source**
+
+ITU-T Recommendation Y.1241 was prepared by ITU-T Study Group 13 (2001-2004) and approved under the WTSA Resolution 1 procedure on 1 March 2001.
+
+## **Keywords**
+
+ATM, B-ISDN, Interworking, IP, Network, PSTN, Service Plane, Service Level Agreement (SLA), Transfer Capability.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
+
+© ITU 2001
+
+All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU.
+
+## CONTENTS
+
+|                                                                           | <b>Page</b> |
+|---------------------------------------------------------------------------|-------------|
+| 1 Scope .....                                                             | 1           |
+| 2 References.....                                                         | 1           |
+| 3 Definitions.....                                                        | 2           |
+| 4 Abbreviations .....                                                     | 3           |
+| 5 IP-based service.....                                                   | 3           |
+| 5.1 General.....                                                          | 3           |
+| 5.2 IP-based service classes and categories.....                          | 4           |
+| 5.3 Communication configurations.....                                     | 5           |
+| 5.3.1 Point-to-point communication configuration.....                     | 5           |
+| 5.3.2 Unidirectional point-to-multipoint communication configuration..... | 5           |
+| 5.3.3 Unidirectional multipoint-to-point communication configuration..... | 5           |
+| 5.3.4 Multipoint-to-multipoint communication configuration .....          | 5           |
+| 5.3.5 Bidirectional point-to-multipoint communication configuration.....  | 6           |
+| 5.4 IP service plane .....                                                | 6           |
+| 5.5 End-system model .....                                                | 8           |
+| 6 IP transfer capability attributes .....                                 | 8           |
+| 6.1 General.....                                                          | 8           |
+| 6.2 Attributes for IP transfer capability.....                            | 9           |
+| 7 Service level agreement.....                                            | 9           |
+| 7.1 General.....                                                          | 9           |
+| 7.2 SLA components .....                                                  | 9           |
+| 7.3 SLA attributes .....                                                  | 10          |
+| 7.3.1 Service level objectives.....                                       | 10          |
+| 7.3.2 Service monitoring .....                                            | 10          |
+| 7.3.3 Financial issues.....                                               | 10          |
+| 7.4 Procedure for service level agreements .....                          | 10          |
+| 8 Protocol reference model.....                                           | 11          |
+| 9 Functional architecture .....                                           | 12          |
+| 9.1 Applications of functional groups .....                               | 12          |
+| 9.1.1 IP interface functional group.....                                  | 13          |
+| 9.1.2 IP routing and forwarding functional group.....                     | 13          |
+| 9.1.3 IP server functional group.....                                     | 13          |
+| 9.1.4 IP client functional group.....                                     | 13          |
+| 9.1.5 IP conversion functional group .....                                | 13          |
+
+|                                                        | <b>Page</b> |
+|--------------------------------------------------------|-------------|
+| 10 Support of IP-based services by ATM .....           | 14          |
+| 10.1 Relationship with ATM transfer capabilities ..... | 14          |
+
+# Support of IP-based services using IP transfer capabilities
+
+# 1 Scope
+
+This Recommendation specifies:
+
+- service plane concept for IP-based services;
+- support of IP-based services by ATM;
+- attributes for IP transfer capabilities to support IP-based services;
+- service level agreement for IP-based services.
+
+By introducing the concept of the service plane, the possible sets of attributes for IP transfer capabilities to support the IP-based services are given.
+
+Figure 1 shows the relationship of this Recommendation with related IP Recommendations.
+
+IP-based services may be supported on IP above any layer 1 and layer 2 transport capable of supporting IP. While Figure 1 shows ATM as the transport mechanism, other underlying transfer mechanisms can be used to provide the same IP-based services. The use of IP over these other transfer mechanisms is described in other Recommendations.
+
+![Figure 1/Y.1241 – Relationship of IP-based services transport and interworking Recommendations. The diagram illustrates the relationship between different service planes and transport mechanisms. On the left, a stack of three layers is shown: 'IP-based service plane' at the top, 'IP transfer capabilities' in the middle, and 'IP Layer' at the bottom. Below this, another stack shows 'ATM transfer capabilities' and 'ATM Layer'. A bracket on the left groups the top two layers under 'Scope of Y.1241' and the bottom two layers under 'Scope of Y.1310'. On the right, a similar stack is shown: 'Telecoms' service plane' at the top, 'Non-IP transfer capabilities' in the middle, and 'PSTN, N-ISDN or ATM Protocol stack' at the bottom. A bracket at the top groups both stacks under 'Scope of Y.1401'. Dotted lines connect the service planes to their respective transfer capabilities and then to the underlying protocol stacks. The reference 'T1317840-01' is at the bottom right.](9791722d75115ddcc599b07d7bc35d73_img.jpg)
+
+Figure 1/Y.1241 – Relationship of IP-based services transport and interworking Recommendations. The diagram illustrates the relationship between different service planes and transport mechanisms. On the left, a stack of three layers is shown: 'IP-based service plane' at the top, 'IP transfer capabilities' in the middle, and 'IP Layer' at the bottom. Below this, another stack shows 'ATM transfer capabilities' and 'ATM Layer'. A bracket on the left groups the top two layers under 'Scope of Y.1241' and the bottom two layers under 'Scope of Y.1310'. On the right, a similar stack is shown: 'Telecoms' service plane' at the top, 'Non-IP transfer capabilities' in the middle, and 'PSTN, N-ISDN or ATM Protocol stack' at the bottom. A bracket at the top groups both stacks under 'Scope of Y.1401'. Dotted lines connect the service planes to their respective transfer capabilities and then to the underlying protocol stacks. The reference 'T1317840-01' is at the bottom right.
+
+**Figure 1/Y.1241 – Relationship of IP-based services transport and interworking Recommendations**
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published.
+
+- [1] ITU-T I.211 (1993), *B-ISDN service aspects*.
+- [2] ITU-T I.313 (1997), *B-ISDN network requirements*.
+- [3] ITU-T I.321 (1991), *B-ISDN protocol reference model and its application*.
+- [4] ITU-T I.327 (1993), *B-ISDN functional architecture*.
+- [5] ITU-T I.371 (2000), *Traffic control and congestion control in B-ISDN*.
+- [6] ITU-T I.414 (1997), *Overview of Recommendations on layer 1 for ISDN and B-ISDN customer access*.
+- [7] ITU-T Y.1310 (2000), *Transport of IP over ATM in Public Networks*.
+- [8] ITU-T Y.1001 (2000), *IP Framework – A framework for convergence of telecommunications network and IP network technologies*.
+- [9] ITU-T Y.1401 (2000), *General requirements for interworking with Internet protocol (IP) based networks*.
+- [10] ITU-T Y.1231 (2000), *IP access network architecture*.
+- [11] ITU-T G.707/Y.1322 (2000), *Network node interface for the synchronous digital hierarchy (SDH)*.
+- [12] ITU-T I.371.1 (2000), *Guaranteed frame rate ATM transfer capability*.
+
+# 3 Definitions
+
+This Recommendation defines the following terms:
+
+**3.1 service plane:** The service plane comprises:
+
+- a) service presentation functionality being presented to the end user;
+- b) service implementation aspects with which the end user interacts. For example, service invocation, control service level agreement function, etc.
+
+Note that a) and b) use the totality of the transfer capabilities including control and management functionalities.
+
+**3.2 IP-based service:** An IP-based service is defined as a service provided by the service plane to an end user (e.g. a host (end system) or a network element) and which utilizes the IP transfer capabilities and associated control and management functions, for delivery of the user information specified by the service level agreements.
+
+**3.3 IP network service:** An IP Network Service is defined as a data transmission service in which the data passed across the interface between the user and provider is transferred in the form of IP (Internet Protocol) packets (sometimes called datagrams). IP Network Service includes the service provided by using the IP Transfer Capabilities.
+
+**3.4 IP transfer capability:** IP Transfer Capability is defined as the set of network capabilities provided by the IP layer. It may be characterized by the traffic contract as well as performance attributes supported by control and management functions of the underlying protocol layers.
+
+**3.5 service level agreement:** Service Level Agreement (SLA) is a negotiated agreement between a customer and the service provider on levels of service characteristics and the associated set of metrics. The content of SLA varies depending on the service offering and includes the attributes required for the negotiated agreement.
+
+# **4 Abbreviations**
+
+This Recommendation uses the following abbreviations:
+
+|        |                                               |
+|--------|-----------------------------------------------|
+| ABR    | Available Bit Rate                            |
+| ABT    | ATM Block Transfer                            |
+| ATM    | Asynchronous Transfer Mode                    |
+| B-ISDN | Broadband Integrated Services Digital Network |
+| CoS    | Class of Service                              |
+| CPN    | Customer Premises Network                     |
+| DBR    | Deterministic Bit Rate                        |
+| FTP    | File Transfer Protocol                        |
+| GFR    | Guaranteed Frame Rate                         |
+| IP     | Internet Protocol                             |
+| IP-NE  | IP Network Element                            |
+| IP-TE  | IP Terminal Equipment                         |
+| IPTC   | IP Transfer Capability                        |
+| LAN    | Local Area Network                            |
+| MPLS   | Multi-Protocol Label Switch                   |
+| OAM    | Operation, Administration and Maintenance     |
+| QoS    | Quality of Service                            |
+| SAP    | Service Access Point                          |
+| SBR    | Statistical Bit Rate                          |
+| SDH    | Synchronous Digital Hierarchy                 |
+| SLA    | Service Level Agreement                       |
+| SLO    | Service Level Objective                       |
+| SVC    | Switched Virtual Circuit                      |
+| TCP    | Transmission Control Protocol                 |
+| UDP    | User Data Protocol                            |
+| UNI    | User Network Interface                        |
+| VoD    | Video-on-Demand                               |
+| WWW    | World Wide Web                                |
+
+# **5 IP-based service**
+
+## **5.1 General**
+
+An IP-based service is defined in clause 3.
+
+An IP-based service is specified according to the Service Level Agreement (SLA) attributes assigned (see clause 7). While an IP-based service usually has an end-to-end context it may be provided in situations in which part of the connection is IP-based network while another part of the connection is
+
+not IP-based. One typical example is a voice service, with voice over IP in an IP-based network interworking with the existing circuit switched voice network. Other examples of non IP-based network interworking with IP-based network to support an IP-based service end to end exist. Further information on IP interworking is given in ITU-T Y.1401 [9]. In the case of interworking, the SLA attributes will be specified only for the IP-based network portion of the connection.
+
+Figure 2 presents a reference framework illustrating applications of IP transfer capability and IP-based services. This figure is based on the figures introduced in ITU-T I.414 [6], ITU-T Y.1001 [8] and Y.1231 [10]. The following subclauses provide information regarding, IP-based services, service plane concept, IP-based service classes and categories and IP transfer capability attributes.
+
+![Figure 2/Y.1241 – IP-based network reference framework](4e0ade2f41b66d5602160da5cc978274_img.jpg)
+
+```
+
+    graph LR
+        subgraph CPN1 [Customer Premises Network]
+            ES1[End System] --> IPNT1[IP-NT]
+        end
+        IPNT1 -- RP --- AF1[AF]
+        AF1 -- RP --- IPEF1[IP-EF]
+        subgraph ICN [IP Core Network]
+            IPEF1 --- IPEF2[IP-EF]
+        end
+        IPEF2 -- RP --- AF2[AF]
+        AF2 -- RP --- IPNT2[IP-NT]
+        subgraph CPN2 [Customer Premises Network]
+            IPNT2 --> ES2[End System]
+        end
+        CPN1 -- IP Transfer Capability --- CPN2
+    
+```
+
+Detailed Description: The diagram illustrates the IP-based network reference framework. It shows two 'Customer Premises Networks' on the left and right, each containing an 'End System' connected to an 'IP-NT' (IP Network Termination). These connect via 'RP' (Reference Points) to 'AF' (Access Function) within an 'Access Network'. The Access Networks then connect via 'RP' to 'IP-EF' (IP Edge Function) which reside at the edges of the 'IP Core Network'. A double-headed arrow labeled 'IP Transfer Capability' spans across the entire architecture from one End System to the other. Clouds represent the service areas for 'IP-Based Service' at each end and the 'IP Core Network' in the center.
+
+AF Access Function  
+ IP-EF IP Edge Function  
+ IP-NT IP Network Termination  
+ RP Reference Point
+
+NOTE – The box between RPs is covered in ITU-T Y.1231 and I.414. This arrangement is also aligned with ITU-T Y.1001.
+
+### Figure 2/Y.1241 – IP-based network reference framework
+
+Figure 2/Y.1241 – IP-based network reference framework
+
+#### 5.2 IP-based service classes and categories
+
+IP-based service classes are closely related to QoS classes which provide assurances to users on the service performance to be achieved in any given service contract. The IP-based services are specified and characterized by the SLA attributes assigned in the service contract.
+
+However, using similar concepts as in ITU-T I.211 [1], IP-based services can be categorized as "Interactive" and "Distributive".
+
+The interactive category is subdivided into three classes:
+
+- conversational services: such as internet telephony, remote login, electronic data exchange, videoconferencing, video telephony, home banking, tele-education and interactive games;
+- messaging services: such as electronic mail (e-mail), voice e-mail, video e-mail, and internet fax;
+
+4 ITU-T Y.1241 (03/2001)
+
+- retrieval services: such as web browsing (www, gopher), file downloading (ftp), internet VoD (Video-on-demand) and news retrieval.
+
+The distributive category is subdivided into two classes:
+
+- distribution services without user individual presentation control: such as broadcasting, multicasting and electronic newspaper;
+- distribution services with user individual presentation control: such as video-on-demand and news-on-demand.
+
+## **5.3 Communication configurations**
+
+Communication in IP-based networks can be divided in several configurations similar to B-ISDN as defined in ITU-T I.313 [2]. In this Recommendation configurations are classified as point-to-point, unidirectional point-to-multipoint, unidirectional multipoint-to-point, multipoint-to-multipoint and bidirectional point-to-multipoint.
+
+### **5.3.1 Point-to-point communication configuration**
+
+A point-to-point connection configuration may provide unidirectional or bidirectional symmetric or asymmetric communication between two parties. Examples of services applicable to point-to-point communication configuration are:
+
+- conversational services;
+- messaging services;
+- retrieval services;
+- distribution services with user individual presentation control.
+
+### **5.3.2 Unidirectional point-to-multipoint communication configuration**
+
+A unidirectional point-to-multipoint connection configuration may provide unidirectional communication between one-to-many parties. Examples of services applicable to unidirectional point-to-multipoint communication configuration are:
+
+- messaging services;
+- distribution services without user individual presentation control.
+
+### **5.3.3 Unidirectional multipoint-to-point communication configuration**
+
+A unidirectional multipoint-to-point connection configuration may provide unidirectional communication between many-to-one parties. Examples of services applicable to unidirectional multipoint-to-point communication configuration are:
+
+- messaging services;
+- distribution services without user individual presentation control.
+
+### **5.3.4 Multipoint-to-multipoint communication configuration**
+
+A multipoint-to-multipoint connection configuration may provide communication between many-to-many parties. Examples of services applicable to multipoint-to-multipoint communication configuration are:
+
+- conversational services;
+- messaging;
+- distribution services with or without user individual presentation control.
+
+### 5.3.5 Bidirectional point-to-multipoint communication configuration
+
+A bidirectional point-to-multipoint connection configuration may provide communication between one-to-many parties. Examples of services applicable to bidirectional point-to-multipoint communication configuration are:
+
+- conversational services;
+- messaging services with return path;
+- retrieval services;
+- distribution services with and without user individual presentation control.
+
+Table 1 provides examples of performance attributes for some IP-based services.
+
+**Table 1/Y.1241 – Examples of guaranteed performance attributes for IP-based services**
+
+| IP-based service class                                       | IP-based service                                                                                                                                       | Guaranteed performance attribute(s) for IP-based service |
+|--------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------|
+| Conversational                                               | <ul style="list-style-type: none"><li>• Internet telephony</li><li>• Videoconferencing</li><li>• Video telephony</li><li>• Interactive games</li></ul> | Loss, delay and delay variation                          |
+|                                                              | <ul style="list-style-type: none"><li>• Internet shopping</li><li>• Electronic data exchange</li></ul>                                                 | Loss                                                     |
+|                                                              | <ul style="list-style-type: none"><li>• Remote login</li></ul>                                                                                         | None                                                     |
+| Messaging                                                    | <ul style="list-style-type: none"><li>• Voice e-mail</li><li>• Internet fax</li><li>• Video e-mail</li><li>• Group e-mail</li></ul>                    | None                                                     |
+| Retrieval                                                    | <ul style="list-style-type: none"><li>• Web browsing</li><li>• News retrieval</li><li>• File downloading</li></ul>                                     | None                                                     |
+|                                                              | <ul style="list-style-type: none"><li>• Video-on-demand</li></ul>                                                                                      | Loss and delay variation                                 |
+| Distribution Service without Individual presentation control | <ul style="list-style-type: none"><li>• Electronic newspaper</li><li>• Internet advertising</li></ul>                                                  | None                                                     |
+|                                                              | <ul style="list-style-type: none"><li>• Live broadcasting</li></ul>                                                                                    | Loss                                                     |
+| Distribution Service with Individual presentation control    | <ul style="list-style-type: none"><li>• News-on-demand</li><li>• Video-on-demand</li></ul>                                                             | Loss and delay variation                                 |
+
+## 5.4 IP service plane
+
+The service plane concept is introduced as a model to relate use of the following in the construction of IP-based services:
+
+- IP transfer capabilities;
+- control capabilities; and
+- management related capabilities.
+
+IP-based services, may be specified within a Service Level Agreement (SLA) between service provider and the customer. This concept is illustrated in Figure 3, which shows that the service plane utilizes the capabilities provided by the underlying transfer functions, as well as the control and management plane functions. Consequently the IP service plane incorporates more than a layer service as defined in a SAP (service access point) in the protocol stack. In specifying an IP-based service for use by a customer the terms and features of clauses 6 and 7 are used.
+
+![Figure 3: Service plane concept for IP-based services. The diagram shows a stack of four planes. The top plane is the 'IP Service plane' containing 'Distribution Services (e.g. news-on-demand)', 'Retrieval Services (e.g. web browsing)', and 'Conversational Services (e.g. IP telephony)'. The second plane is 'IP transfer capabilities' containing 'Best effort', 'IPTC y', and 'IPTC x'. The third plane is the 'IP management plane' divided into 'IP user plane' and 'IP control plane'. The bottom plane is the 'Management plane' divided into 'User plane' and 'Control plane'. The 'ATM transfer capabilities' plane is shown below the IP management plane, containing 'ABR', 'DBR', 'SBR', and 'ABT'. The diagram is labeled T1317860-01.](4e4be0bd8b235167902f2c03e41da651_img.jpg)
+
+The diagram illustrates the service plane concept for IP-based services, structured into four main layers:
+
+- IP Service plane:** Contains three service categories:
+  - Distribution Services (e.g. news-on-demand)
+  - Retrieval Services (e.g. web browsing)
+  - Conversational Services (e.g. IP telephony)
+- IP transfer capabilities:** Contains three transfer capabilities:
+  - Best effort
+  - IPTC y
+  - IPTC x
+- IP management plane:** Divided into two sub-planes:
+  - IP user plane
+  - IP control plane
+- Management plane:** Divided into two sub-planes:
+  - User plane
+  - Control plane
+
+Below the IP management plane, the **ATM transfer capabilities** are shown, including ABR, DBR, SBR, and ABT. The diagram is labeled T1317860-01.
+
+Figure 3: Service plane concept for IP-based services. The diagram shows a stack of four planes. The top plane is the 'IP Service plane' containing 'Distribution Services (e.g. news-on-demand)', 'Retrieval Services (e.g. web browsing)', and 'Conversational Services (e.g. IP telephony)'. The second plane is 'IP transfer capabilities' containing 'Best effort', 'IPTC y', and 'IPTC x'. The third plane is the 'IP management plane' divided into 'IP user plane' and 'IP control plane'. The bottom plane is the 'Management plane' divided into 'User plane' and 'Control plane'. The 'ATM transfer capabilities' plane is shown below the IP management plane, containing 'ABR', 'DBR', 'SBR', and 'ABT'. The diagram is labeled T1317860-01.
+
+NOTE – This figure shows ATM being used for transport. Other transport technologies (e.g. Frame relay, SDH, etc.) may also be applied using the same principle.
+
+**Figure 3 /Y.1241 – Service plane concept for IP-based services**
+
+## 5.5 End-system model
+
+Figure 4 shows an end-system model. In this model, the IP end-system has two types of interface points; one is the socket API (Application Programming Interface) and the other is the interface to the IP transfer capability. The socket API allows IP applications to use capability provided by TCP layer (e.g. TCP or UDP). The interface to the IP transfer capability provides access to desired IP transfer capabilities for a given IP-based service.
+
+![Diagram of the IP end-system model showing the flow from IP Application through TCP/UDP and IP protocol stack to IP-NT.](4ee27dbf5ef12e7b58b0ef0937bc5a5e_img.jpg)
+
+The diagram illustrates the IP end-system model. At the top, an 'IP-based Service' is indicated by an upward arrow. Below it, an 'IP Application' (represented by a grey oval) interacts with a 'Stream' (represented by a circle) within a 'TCP/UDP' layer (represented by a 3D box). A 'Datagram' (represented by a circle) is also shown within the 'TCP/UDP' layer. A 'Socket API' (represented by a rectangle) is positioned between the 'IP Application' and the 'TCP/UDP' layer. Below the 'TCP/UDP' layer is the 'IP protocol stack' (represented by a 3D box), which contains 'BE' (Best Effort), 'IPTC y', and 'IPTC x' (all represented by circles). A horizontal line connects the 'IP protocol stack' to an 'IP-NT' (IP Network Termination) block (represented by a grey 3D box). A dashed line encloses the 'IP Application', 'TCP/UDP', and 'IP protocol stack' components, with the label 'IP end-system' at the bottom. A horizontal line also connects the 'IP-NT' block to a reference number 'T1317870-01'.
+
+Diagram of the IP end-system model showing the flow from IP Application through TCP/UDP and IP protocol stack to IP-NT.
+
+BE Best Effort  
+CPE Customer Premises Equipment  
+IP-NT IP Network Termination
+
+NOTE – IP transfer capabilities include user, control and management plane functions.
+
+**Figure 4/Y.1241 – IP end-system model**
+
+# 6 IP transfer capability attributes
+
+## 6.1 General
+
+The IP transfer capabilities, as defined in another ITU-T Recommendation, can be used to characterize capabilities provided by the IP layer. The transport of data packets may be provided by an IP transfer capability (including a set of parameters) and a QoS class.
+
+Figure 2 depicts how the concept of IP transfer capability and IP QoS class can be applied. In this application, the IP Transfer Capability is specified at the RP (reference point) interface, e.g. the boundary between customer side and provider side. The IP QoS class characterizes the properties of the transport between two RPs, e.g. the ingress and the egress boundaries between customers and the network. Network operators could use these concepts to offer an IP-based service to their customers.
+
+The IP transfer capability, including all relevant parameter values, and the QoS class may be used in preparation of a SLA (see clause 7).
+
+## **6.2 Attributes for IP transfer capability**
+
+An IP transfer capability with an associated IP QoS class is intended to support an IP-based service with the desired performance attributes. In order to reach that objective, this Recommendation lists a number of properties which IP transfer capabilities (to be specified in other Recommendations) should have:
+
+- IP transfer capabilities should support IP-based Services as specified in this Recommendation;
+- IP transfer capabilities should be implicitly or explicitly declared at the moment the service is requested;
+- an IP transfer capability is not required to have a one-to-one correspondence with a given IP-based service. That is, there may be more than one IPTC which is able to support the requested IP-based service.
+
+# **7 Service level agreement**
+
+## **7.1 General**
+
+To support a given IP-based service a Service Level Agreement (SLA) is negotiated between a customer and a service provider. The SLA is a formal contract between the service provider and the customer that defines the terms of the service provider's responsibility to the customer, the type and extent of penalty if those responsibilities are not met and the price of the service provided. A service level agreement is a document, which may be written by the customer, service provider, or both, to define specific levels of service and the associated financial aspects.
+
+A complete SLA document may include the names of the parties involved, the terms of the agreement, the application and support services to be provided, the service level objectives, and the attribute values. The SLA may also include reporting requirements (including both the frequency of report generation and the level of reporting detail), penalties for non-compliance with the agreement, arbitration policies, modification terms, and responsibilities of both parties.
+
+## **7.2 SLA components**
+
+The SLA should be composed of three building blocks:
+
+- service level objectives;
+- service monitoring components;
+- financial compensation components.
+
+Service level objectives (SLOs) are specific service metrics, including service performance. Service monitoring involves either the customer or the service provider use of monitoring devices to ensure compliance to the terms of the contract. The financial component may include service price information as well as the penalties for the service provider's failure to meet the requirements of the SLA.
+
+## **7.3 SLA attributes**
+
+The following SLA attributes may be considered as appropriate in the development of a Service Level Agreement.
+
+### **7.3.1 Service level objectives**
+
+- IP transfer capability;
+- QoS Parameters or CoS provided;
+- availability – access blocking probability;
+- reliability – active system time, network failure rate;
+- interoperability;
+- delivery confirmation;
+- mobility and Portability support;
+- security – encryption, etc.;
+- bandwidth – constant, variable, etc.;
+- priority;
+- authentication – User ID for admission control;
+- signalling protocols – CR-LDP, etc.;
+- flexibility – scaling and global connectivity;
+- life of the SLA.
+
+### **7.3.2 Service monitoring**
+
+- QoS monitoring – comparison against objectives;
+- flow tracking – comparison against IPTC objectives;
+- tracking – time stamping at the beginning and end of session;
+- reports on service level objectives as necessary.
+
+### **7.3.3 Financial issues**
+
+- billing option – flat rate, timed, per transaction, per packet, etc.;
+- penalties for failing to deliver service level objectives by the service provider;
+- pricing;
+- early termination charges;
+- shortfall charges – early withdrawal from service by the customer.
+
+SLAs may be between the customer and the service provider or between the service provider and the provider of the network.
+
+## **7.4 Procedure for service level agreements**
+
+The following steps may be taken when developing and implementing a service level agreement.
+
+The procedure in the development of the SLA includes identification of:
+
+- the customer and associated service level;
+- network performance objectives;
+- ways to revise the network configuration and resource management;
+- ways to revise the service level agreement.
+
+The implementation of the SLA in the network occurs in the following steps:
+
+- design and provisioning of the network to satisfy the SLA;
+- configuration of ingress device as per information in the policy server to satisfy the SLA;
+- classification of the packets into different classes and collection of statistics regarding their performance at ingress device;
+- verification of the SLA based on the collected data from the ingress device.
+
+# **8 Protocol reference model**
+
+The protocol reference model for IP transport network is composed of a user-plane (U-plane), a control-plane (C-plane) and a management-plane (M-plane) similar to that of ITU-T I.321 [3]. Figure 5 shows the model for the IP-based network.
+
+The user-plane provides user information flow transfer on the IP-based network. In the layer architecture model, it consists of TCP/UDP layer, IP layer and lower transport layers. To meet the IP-based service features; the user-plane network capabilities include among others, connection types and IP transfer capabilities and ATM transfer capabilities in the case of ATM.
+
+The control-plane performs the call and connection control functions to support connection-oriented (e.g. MPLS) as well as connectionless services. It provides necessary signalling between the user and the network. To provide the IP-based services, the control-plane network capabilities include on-demand control capabilities of user-plane transfer functions, call/connection signalling, traffic negotiation, addressing, routing functions and user, terminal, and/or service identification.
+
+The management-plane has two types of management functions namely layer management and plane management. The layer management performs management functions on resources and parameters of lower layer transport protocol entities. It handles the general operation and maintenance of each protocol layer to meet the QoS requirements on user information flows. The plane management performs system management functions with coordination with the U-plane and the C-plane capabilities. With the help of plane management capabilities, the IP network provides the high-level client/server applications and user, terminal and/or service interaction. It also provides network-related and service-oriented high layer capabilities such as naming, information searching, data storing, information transaction, etc.
+
+![Figure 5/Y.1241 – Protocol reference model for IP-based networks. The diagram shows a Network Management block on the left connected to an Element Management block on the right. The Element Management block is divided into three planes: M-plane (Plane Management), C-plane (Call & Connection Control), and U-plane (User Applications). Below these planes are three layers: TCP/UDP Layer, IP Layer, and Lower Transport Layers. A Layer Management block is also shown, connected to the M-plane and the TCP/UDP Layer. Arrows indicate bidirectional communication between the Network Management and Element Management, and between the various components within the Element Management block.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+The diagram illustrates the protocol reference model for IP-based networks. It is divided into two main sections: Network Management and Element Management. The Network Management block is on the left, connected to the Element Management block on the right. The Element Management block is further divided into three planes: M-plane (Plane Management), C-plane (Call & Connection Control), and U-plane (User Applications). Below these planes are three layers: TCP/UDP Layer, IP Layer, and Lower Transport Layers. A Layer Management block is also shown, connected to the M-plane and the TCP/UDP Layer. Arrows indicate bidirectional communication between the Network Management and Element Management, and between the various components within the Element Management block.
+
+Figure 5/Y.1241 – Protocol reference model for IP-based networks. The diagram shows a Network Management block on the left connected to an Element Management block on the right. The Element Management block is divided into three planes: M-plane (Plane Management), C-plane (Call & Connection Control), and U-plane (User Applications). Below these planes are three layers: TCP/UDP Layer, IP Layer, and Lower Transport Layers. A Layer Management block is also shown, connected to the M-plane and the TCP/UDP Layer. Arrows indicate bidirectional communication between the Network Management and Element Management, and between the various components within the Element Management block.
+
+**Figure 5/Y.1241 – Protocol reference model for IP-based networks**
+
+# 9 Functional architecture
+
+In this Recommendation the functional architecture of IP-based networks is explained in a similar manner as in ITU-T I.327 [4].
+
+## 9.1 Applications of functional groups
+
+IP-based networks are comprised of two functional groups: the IP-network element (IP-NE) and the IP terminal equipment (IP-TE). The IP-NE functional group has the network intelligence to configure, register, control and manage the IP-based services. It may be interfaced to the Internet Service Provider's network. The functional groups can be categorized in three groups where each can be sub-categorized again. The following provides a list of these categories with a brief explanation for each one:
+
+- IP-Terminal Equipment (IP-TE): IP Interface Functional Group and IP Client Functional Group;
+- IP-Router: IP Interface Functional Group and IP Routing and Forwarding Functional Group (and IP Server Functional group optionally);
+- IP-Interworking Unit (IP-IWU): IP Interface Functional Group and IP Conversion Functional Group (and IP Server Functional group optionally).
+
+The list of functions for each functional group is not exhaustive. Also, not all specific functions in a functional group need to be present in all implementations.
+
+### **9.1.1 IP interface functional group**
+
+This functional group includes interface functions to generate and receive IP messages for the specific Internet applications. Examples of IP interface functions are:
+
+- generation and extraction of IP messages specific to end user applications;
+- buffering and resource allocation;
+- multiplexing and de-multiplexing;
+- provisioning of virtual circuits with or without signalling protocol handling;
+- traffic flow handling including usage parameter control;
+- physical transmission interface and adaptation functions;
+- transmission control including OAM functions.
+
+Additional functions specific to the transmission system or high-level services and applications may be required.
+
+### **9.1.2 IP routing and forwarding functional group**
+
+This functional group includes forwarding and routing functions to transfer IP messages to the destinations. Examples of IP routing and forwarding functions are:
+
+- storing and forwarding of IP messages;
+- routing information handling for static or dynamic routing;
+- topology information handling;
+- provisioning of QoS assured path.
+
+### **9.1.3 IP server functional group**
+
+This functional group includes the server-side functions for configuration and registration procedure of IP network. Examples of IP server functions are:
+
+- server-side functions for registration procedure of IP address and name;
+- server-side functions for registration procedure of IP multicast and broadcast group;
+- directory service with efficient and distributed storage;
+- response to the query of IP address and name;
+- maintenance of mapping between IP address and IP domain name.
+
+### **9.1.4 IP client functional group**
+
+This functional group includes the client-side functions for configuration and registration procedure in IP networks. Examples of IP client functions are:
+
+- client-side functions for registration procedure of IP address and name;
+- client-side functions for registration procedure of IP multicast and broadcast group;
+- query of IP address and name.
+
+### **9.1.5 IP conversion functional group**
+
+This functional group includes the functions for protocol conversion and format translation in IP network for the specific Internet applications. Examples of IP conversion functions are:
+
+- translation of IP protocol functionality, for example, to convert the UDP messages to the TCP messages or vice versa (e.g. transport gateway, signalling);
+- mapping of IP versions (e.g. IPv4, and IPv6, etc.);
+
+- conversion of connection types, for example, to translate one point-to-multipoint connection to multiple point-to-point connections;
+- change of transfer mode, for example, to translate the connectionless transfer mode to the connection-oriented transfer mode;
+- conversion of QoS provisioning, for example, to deliver the best effort service to the guaranteed service with high priority;
+- IP traffic control and management handling.
+
+# 10 Support of IP-based services by ATM
+
+ITU-T Y.1310 [7] specifies transport of IP over ATM in public networks and ITU-T Y.1401 [9] provides general requirements for Interworking with IP-based networks. For a detailed discussion regarding these subjects, the aforementioned and other relevant Recommendations should be consulted. This clause provides examples of IP performance attributes mapped to ATM QoSs to support IP-based services.
+
+## 10.1 Relationship with ATM transfer capabilities
+
+ITU-T I.371 [5] provides ATM transfer capability. Transfer capabilities carry varying QoS objectives. QoS objectives for IP-based services, like in ATM, are dependent on the sensitivity of transferred data to loss and delay. Hence, in this clause, loss, delay variation and delay attributes are chosen as a means to relate performance attributes for IP-based services to the ATM QoS classes as specified in ITU-T I.356.
+
+Clause 5.2 identifies IP-based services as to belong to two categories and five classes based on their performance attributes. Table 2 provides examples of how performance attributes of IP-based services can be related to ATM QoS classes.
+
+**Table 2/Y.1241 – Examples of relationship between performance attributes for IP-based services and ATM QoS classes**
+
+| <b>Guaranteed performance attribute(s) for IP-based service</b> | <b>Possible mapping (s) to ATM QoS</b>                                                          |
+|-----------------------------------------------------------------|-------------------------------------------------------------------------------------------------|
+| Loss, delay and delay variation                                 | QoS class 1 (stringent class)<br>or<br>QoS class 5 (stringent bi-level class) for CLP = 0 cells |
+| Loss                                                            | QoS class 2 (tolerant class)<br>or<br>QoS class 3 (bi-level class) for CLP = 0 cells            |
+| None                                                            | QoS class 4 (U class)<br>or<br>QoS class 3 (bi-level class) for CLP = 1 cells                   |
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                |
+|-----------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                              |
+| Series B        | Means of expression: definitions, symbols, classification                                                                      |
+| Series C        | General telecommunication statistics                                                                                           |
+| Series D        | General tariff principles                                                                                                      |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                              |
+| Series F        | Non-telephone telecommunication services                                                                                       |
+| Series G        | Transmission systems and media, digital systems and networks                                                                   |
+| Series H        | Audiovisual and multimedia systems                                                                                             |
+| Series I        | Integrated services digital network                                                                                            |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                    |
+| Series K        | Protection against interference                                                                                                |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant                                        |
+| Series M        | TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                |
+| Series O        | Specifications of measuring equipment                                                                                          |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                   |
+| Series Q        | Switching and signalling                                                                                                       |
+| Series R        | Telegraph transmission                                                                                                         |
+| Series S        | Telegraph services terminal equipment                                                                                          |
+| Series T        | Terminals for telematic services                                                                                               |
+| Series U        | Telegraph switching                                                                                                            |
+| Series V        | Data communication over the telephone network                                                                                  |
+| Series X        | Data networks and open system communications                                                                                   |
+| <b>Series Y</b> | <b>Global information infrastructure and Internet protocol aspects</b>                                                         |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                           |