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51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.1.5 Physical Properties | Physical properties of a device often reveal what types of hidden functionalities the analysis is likely to expose. All the ports and the connectors that are visible to outside world are obvious targets for the analysis. It is also possible to disassemble the device to get further information on the potential interfaces to connect to. These could be, for example: • Memory slots • Disconnected, but easily re-enabled ports • Debugging ports on the circuit board In an examination of a device's physical properties, the following features should also be taken into account: • All the ports and slots the device has for interconnectivity • Power slots • Buttons • External connectors |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.1.6 Configuration | The device configurations used to build the service should be examined to gain knowledge of the device itself as well as the possible open interfaces. Different services available on the device can result in different configurations. For this reason, it is important to know which are the potentially available services and not only what is enabled on the device in its default or current configuration. ETSI ETSI TR 101 590 V1.1.1 (2013-03) 17 |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.1.7 User Interface | The purpose of the user interface inspection is to gain insight into the processes running in a system. The systematic observation of the available applications and the configurations they allow is likely to reveal interfaces that would never be located with external monitoring methods. Examples of such interfaces are different images, archives, audio formats and certificate stores. Many of the device's applications initialize client-side connections and accept these formats. |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.2 Expected outcome of Attack Surface Analysis | As stated earlier, modern networks are extremely sophisticated and while the complexity is increasing, the security requirements are becoming stricter. It is apparent that random testing is no longer a viable option for testing network level connections. Attack surface analysis facilitates threat analysis on two different levels. While helping to identify the most critical interfaces, it can also assist in finding and shutting down unnecessary open ports or services. By minimizing unnecessary complexity, customer support cases and security exposures can be prevented and the testing effort can be concentrated on truly critical interfaces. 8.3 Attack Surface Analysis for example architecture by studying the interfaces In our example analysis, we can only access Wiki-based specifications. Therefore we cannot rely on port scanning, traffic monitoring, on-host monitoring, or physical properties of devices. Since it is not a concrete, real-world deployment, some assumptions about the protocols and their termination points are necessary. Port scanning and passive monitoring were deemed likely to expose additional data paths and termination points. After all, an example should give a fairly realistic view, no matter how limited it is. For prioritization, the CVSS Exploitability Metric was used (explained later). |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.3.1 Interfaces and protocols | Interface list in table 1 considers interfaces which terminate signaling that originates from the UE or from outside the network, or performs packet translation for data originating from these sources. In addition to the protocols listed above, it is likely that protocols like DHCP, IPSec, and SigComp are found in the network. Since the termination points are not obviously based on the attached diagram they are not included in the analysis, even though in a real-world scenario they should be. Table 1: Example list of interfaces in IMS Interface Protocols Comment UE-SGSN GTP UE- WLAN WAG 802.11 UE-P-CSCF SIP Commonly replaced with Session Border Controller UE-S-CSCF SIP UA-AS HTTP, XCAP Subscriber information UE-IMS-MGW RTP IPv4/6-BG IPv4, IPv6 UE - IPv4 PDN User plane protocols End-to-end traffic originating from UE and terminating in IPv4 PDN It is also important to test the routing protocols and Layer 2 switching protocols, which are overlooked by this example. While these protocols are more challenging to attack than application level protocols, both have had their share of security incidents. Data paths are more difficult to predict with these protocols and applying perimeter security is challenging. Therefore the key is to ensure the robustness of the devices implementing the routing and switching functions. ETSI ETSI TR 101 590 V1.1.1 (2013-03) 18 |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.3.2 CVSS Scoring | The CVSSv2 Exploitability Metric was used to prioritize the interfaces. CVSS is an industry standard for classifying vulnerabilities [i.15]: "The Common Vulnerability Scoring System (CVSS) provides an open framework for communicating the characteristics and impacts of IT vulnerabilities. CVSS consists of 3 groups: Base, Temporal and Environmental. Each group produces a numeric score ranging from 0 to 10, and a Vector, a compressed textual representation that reflects the values used to derive the score. The Base group represents the intrinsic qualities of a vulnerability. The Temporal group reflects the characteristics of a vulnerability that change over time. The Environmental group represents the characteristics of a vulnerability that are unique to any user's environment. CVSS enables IT managers, vulnerability bulletin providers, security vendors, application vendors and researchers to all benefit by adopting this common language of scoring IT vulnerabilities." While the primary use case of CVSS is to estimate the impact of realized vulnerabilities, Exploitability Metrics provide an easy subset for calculating numerical values for potential threat. Components and component values of the Exploitability Metrics are: • Access Vector (AV) 1) Network [N] 2) Adjacent network [A] 3) Local [L] 4) Undefined • Access Complexity [AC] 1) Low [L] 2) Medium [M] 3) High [H] 4) Undefined • Authentication (Au) 1) None [N] 2) Single instance [S] 3) Multiple instances [M] 4) Undefined The highest score and the highest risk (10) is accredited to an interface with the following features: 1) Access Vector: Network 2) Access Complexity: Low 3) Authentication: None Expressing this vector using the terms defined in the CVSS Guide provides: AV:[N]/AC:[L]/Au:[N]. This format was used to create a table presented in the next clause. For details on how to calculate the numerical values, please refer to CVSS equations. ETSI ETSI TR 101 590 V1.1.1 (2013-03) 19 |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.3.3 Scoring | Only one protocol from each interface will be included in this analysis. While it is important to analyze end-to-end user plane protocol traffic, the scores calculated for this interface are very general. To be able to calculate the scores more accurately, we should have more information about the level of user plane traffic parsing, for example from deep packet inspection, filtering and compression taking place within the network. The functions/nodes should then be identified and the vectors calculated for them individually. IPv4 Packet Data Network interface towards the IMS Transport layer is omitted, because there are no details on the implementation. Table 2: Attack vector scores for IMS interfaces Interface Protocol Vector CVSS Score Comment UE-SGSN GTP AV:[N]/AC:[H]/Au:[N] 4,9 UE- WLAN WAG 802.11 AV:[N]/AC:[M]/Au:[N] 8,6 UE-P-CSCF SIP AV:[N]/AC:[L]/Au:[N] 10 UE-S-CSCF SIP AV:[N]/AC:[L]/Au:[S] 8 UA-AS HTTP AV:[N]/AC:[L]/Au:[S] 8 UE-IMS-MGW RTP AV:[N]/AC:[M]/Au:[S] 6,8 UE- IPv4/6-PDN IPv4 AV:[N]/AC:[M]/Au:[S] 8,6 |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.4 Attack Surface Analysis conclusions and recommendations | The purpose of the Attack Surface Analysis is to identify the most critical interfaces and to help in prioritizing the testing effort. In an ideal world, all the interfaces would be tested, but in reality, budgets, deployment schedules and the availability of tools often impose limitations on what is feasible. Thorough attack surface analysis facilitates the selection process and it is equally important for the outcome of the tests to eliminate unnecessary open services and ports. |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.4.1 Attack Surface Analysis as part of Threat Analysis | When looking at threat analysis from protocol perspective, the attack surface analysis is clearly a critical component. In addition, the motivations and the likelihood of an attack should be considered when making the final decision about what to test. Factors like financial gain or the possibility to acquire user database information increase the likelihood of attacks. Overall threat analysis is a broader topic than protocol level analysis and therefore it is out of the scope the present document. On the other hand, factors like the physical tampering of devices, access control, and IT policies on passwords are considered. It should be noted that CVSS is just one possible way of prioritizing interfaces for testing. There are other formal classification methods and in many cases common sense is enough. In this example, the impact of compromising interface has not been taken into account. For example, attacking the WLAN Gateway has a high score, but it is questionable how serious the damage caused by compromising it could be. For applying CVSS more broadly in threat analysis, the use of Impact Metrics can be considered. Impact Metrics is another component of the CVSS Base Score and it provides a tool for estimating the impact of compromising a certain function or service. |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.4.2 Alternative perspectives on Attack Surface and Threat Analysis | This case study was written from the perspective of a service provider and the threat was considered to come from outside. As mentioned earlier in the introduction of this case study, other relevant perspectives are the network equipment manufacturer view and the trust boundaries between operators. |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.4.3 Attack Surface Analysis of network equipment | When performing the attack surface analysis on a single network device, the framework presented earlier still applies but the focus is slightly different compared to the service level analysis. The most important premise for analysis is that no assumptions about the open interfaces can be made. In service level analysis, it is no longer necessary to concentrate on the interfaces used. Indeed, on a device level all the interfaces should be hardened. Even management ports, which were never meant to be accessed through outside local network, may be accidentally enabled. ETSI ETSI TR 101 590 V1.1.1 (2013-03) 20 In a network equipment level analysis, the physical properties and the configurations/user interface can be given more attention compared to a service level analysis. Scanning the device and passive monitoring are not as crucial, since the supported protocols are known. From an auditing perspective it might still be a good idea to check that the enabled services match the configuration and specifications. |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 8.4.4 Trust boundaries as Attack Surface | Technical part of the trust boundary attack surface analysis is very similar to a case presented earlier. The interfaces and protocols forming boundaries between operators are identified and their exploitability and impact of incidence are estimated. To keep the metrics comparable, it is important to decide whether trust boundaries are analyzed as a separate case or together with external threats. This should be clearly stated in all report. In case both external interfaces and trust boundaries are considered, it is probably safest to analyze them on the same scale. On one hand, trust boundaries are more protected than external interfaces, but on the other hand, the exposure of critical information and functions is also much greater with trust boundaries. This is true both in terms of functions with granted access over trust boundaries and the number of protocols exposed. Therefore, in the assessment of the possibility of an attack and the magnitude of its impacts play a crucial role in the overall threat analysis involving trust boundaries. |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 9 Test plans and certification | |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 9.1 Robustness test plan | In creating robustness test cases for a protocol, the number of different possible inputs is infinite. For this reason, a subset of inputs covering the largest possible number of different protocol messages and elements with the best possible test efficiency should be carefully selected and created. In systematic test material creation, the goal should be to apply anomaly values for every element in the protocol PDU (including structural level anomalies, like leaving an element out of the PDU altogether) and for all the PDU's used by a given protocol. In addition, message sequence level anomalies should be present in good quality robustness test set. Repeating messages, omitting messages from a sequence and sending unexpected messages can confuse the protocol parser state machine with serious consequences, should these vulnerabilities remain in the production version. Any available tools for code coverage metrics can be used to provide information on the proportion of software statements covered by the tests. From the test plan creation perspective the fact that the number of possible input combinations is infinite imposes some differences compared to interoperability test plans. It will not be possible to define the input data for all the test cases since the typical case amount varies from thousands to hundreds of thousands, depending on the protocol. It is still possible to describe a test setup including protocols, message sequences and tested network elements in detail. The suggestion is to limit the amount of details on this level and to provide each test scenario with an example of all the anomalous messages sent during the test. |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 9.2 Robustness certification | To date, no vendor-independent certification body or process exists for robustness testing in the telecommunication industry. The basic challenge with robustness certification reflect the difference between interoperability test plans and robustness test plans: Traditional certification assumes that the inputs of a system are specified in detail and the expected response from the SUT is equally carefully specified. As discussed in the previous clause, it is not feasible to provide detailed specifications on all the robustness test inputs. In the case of certification, the pass/fail criteria also cause equal challenges. The original fuzzing criteria "component crash" or "no crash" are still valid, but the milder problem indicators, such as excess processor power consumption or excess memory consumption/corruption, are harder to detect and judge. The responses from the SUT are difficult to verify because one may argue that it is equally fine for an implementation just to ignore anomalous request than to return an error code. ETSI ETSI TR 101 590 V1.1.1 (2013-03) 21 Furthermore, passing the robustness tests is in not a guarantee for a vulnerability-free system. A complete security audit of a system requires many actions besides robustness analysis and it should also cover analysis of the design of the system in general, its usability, and other security aspects. Robustness analysis can be used as an integral part of a complete audit, or as a standalone method to provide insight into the security and quality of the tested software component. Therefore, the certification should indicate a tolerance of anomalous protocol input, i.e. robustness, and it should not be confused with an all-around security certificate. Should robustness certification be pursued, the tools criteria used in the certification should be defined in vendor neutral, yet concrete, terms. The tool criteria should include requirements on test material coverage, for example, it should guarantee tests for all elements of the PDU, all the PDU's used in the protocol and sequence level tests. SUT monitoring mechanisms and common practices for pass/fail verdicts should also be agreed on. Despite the challenges with robustness certification, it is an interesting topic for further discussion. There are clear indicators that the role of fuzzing and robustness testing is growing as companies are seeking to increase built-in security rather than adding security features on top of inherently insecure systems. Therefore, it is conceivable that the interest for robustness certification will also increase. |
51b426e7d58b8e090a8f9ad226a3610f | 101 590 | 10 Conclusions and further work | In the present document, we have discussed robustness testing and its relation to fuzzing. The role of robustness testing in industry was discussed, before taking a deeper look at the technical aspects of robustness testing tools and the fuzzers on the market today. Relations between robustness testing, attack surface analysis and threat analysis were also illustrated using a case study, and finally, some ideas for future work were discussed. In addition to agreeing on a format for test plans and certification considerations, further work on attack surface- and threat analysis on LTE, IMS, and IPTV networks could be in the general interest for future work. An example of test plan is contained in archive tr_101590v010101p0.zip which accompanies the present document. ETSI ETSI TR 101 590 V1.1.1 (2013-03) 22 History Document history V1.1.1 March 2013 Publication |
63690b205142be3574b7b253769796a3 | 101 118 | 1 Scope | The present document is to investigate, address and describe possible High level Network Architectures and Solutions for Number Portability of ITU-T Recommendation E.164 [3] numbers in the fixed telecommunications Network. The following is included in the present document: a) possible Network Architectures and solutions to support number portability; b) Pros and Cons for described Number Portability solutions and influences on services; c) management issues with regard to NP and selected Data Base solution; d) the exchange of NP related information between Networks per solution; e) routeing issues with relation to NP and described solution. The following types of number portability is to be covered: 1) service provider portability of Geographic Numbers; 2) service provider portability of Non Geographic Numbers. NP solutions both for Routeing of ordinary calls and for Routeing of connection less supplementary services (e.g. CCBS) are included. |
63690b205142be3574b7b253769796a3 | 101 118 | 2 References | References may be made to: a) specific versions of publications (identified by date of publication, edition number, version number, etc.), in which case, subsequent revisions to the referenced document do not apply; or b) all versions up to and including the identified version (identified by "up to and including" before the version identity); or c) all versions subsequent to and including the identified version (identified by "onwards" following the version identity); or d) publications without mention of a specific version, in which case the latest version applies. A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same number. [1] ITU-T Recommendation E.164: "International telecommunications numbering plan". |
63690b205142be3574b7b253769796a3 | 101 118 | 3 Definitions, symbols and abbreviations | |
63690b205142be3574b7b253769796a3 | 101 118 | 3.1 Definitions | For the purposes of the present document the following definitions apply: In the following a number of definitions are listed, for used but not included definitions please see TR: "High Level Description of Number Portability". Data Base (DB): A DB is, within the present document, the storage place where a translation of a Portable Number to a Routeing Number (RN) takes place. Other NP related information might exist in same place. The other information might be of either traffical or administrative nature. The other traffical information might be retrieved/used at same time as retrieving the RN. TR 101 118 V1.1.1 (1997-11) 9 The DB might be located exchange internal or external depending on Network solution. Directory Number (DN): A DN is a number in the national numbering scheme that is allocated to a customer for a telephony service. Allocation of the DN is either made directly by the Numbering Plan Administration (NPA) to the customer, or indirectly when blocks of numbers are managed by Service Providers. The DN is the number that is dialled by the users to reach the customer (potentially with prefix and/or with suffix). donor exchange: A donor exchange is the initial exchange where a number was located before ever being ported. donor network: donor network is the initial network where a number was allocated by the NPA before ever being ported. donor service provider: A donor service provider is the service provider from whom the number is ported. essential service: An essential service is a service that should be executed to allow the call to be continued. Examples of essential services are User to User 1 essential and Closed User Group without outgoing access allowed. The service is considered not possible to execute when transfer of the service related data is not possible, e.g. to protocol limitations or bilateral agreements. Gateway Exchange (GW): A GW is, within the present document, an Exchange that has Point of Interconnection(-s) to Exchange(-s) in other Networks. Geographic Number (GN): A GN is a DN from that part of the national numbering scheme that is used to identify fixed line termination. Prior to Number portability these numbers are geographical in that sense that they conveyed the detailed location of the customer. Geographic Number Portability (GNP): See Service Provider Portability for Geographic Numbers. Network Operator: A Network Operator is an entity that operates public telecommunications network in order to route calls. Non Geographic Number (NGN): NGN is a Directory number that is not a Geographic Number. A Non-geographic Number does not imply the Geographic location of the customer. Non Geographic Number Portability (NGNP): See Service Provider Portability for Non Geographic Numbers. Number overview: The Table 1 below shows a simplified overview of Numbers involved in Number Portability, it also exemplifies Non-Geographic Numbers. Table 1: Relationship between Geographic and Non Geographic Numbers DIRECTORY NUMBER GEOGRAPHIC NUMBER NON-GEOGRAPHIC NUMBER ETNS Number Mobile Number Service Number Other Non Geographic Number NOTE: These are examples of non geographic numbers only, and are not prescriptive1 Mobile Number: A Mobile Number (MN) is a Directory Number from a specific range of the national numbering scheme reserved for customers to mobile service(s). MN Portability is outside the scope of this report. Onward Routeing Exchange (ORE): An Onward Routeing Exchange is, within this document, an Exchange within an Onward Routeing Network (ORN) that makes use of a Routeing Number to route a call onward towards a Recipient Network/Exchange. Onward Routeing Network (ORN): An Onward Routeing Network (ORN) is, within this document, a Network that makes use of a Routeing Number to route a call onward towards a Recipient Network/Exchange. Originating Exchange: Originating Exchange IS the Exchange where the calling party is located. For most incoming international calls, the Originating Exchange is effectively the international gateway Exchange. TR 101 118 V1.1.1 (1997-11) 10 For carrier selection, the first exchange of the selected carrier effectively becomes the Originating Exchange for routeing purposes. Originating Network: Originating Network is the network where the calling party is connected. For most incoming international calls, the originating network is effectively the network containing the international gateway. For carrier selection, the first exchange of the selected carrier effectively becomes the originating network for routeing purposes. Portable Number (PN): A PN)is, within the present document, a DN that a subscriber can port when changing Service Provider. A PN can e.g. have one of the following statuses: a) vacant and not ported; b) used and not ported; c) ported. A Ported Number is both Ported-in (Recipient Network) and Ported-out Donor Network) at the same time. Ported Number: A number that has been subject to number portability. Ported-in Number: A ported-in number is, within this document, a Portable Number that has been ported into a Recipient Network/Exchange. Ported-out Number: A ported-out number is, within this document, a Portable Number that has been ported out of a Donor Network/Exchange. Recipient Exchange: A Recipient Exchange is the new Exchange where a number is located after being ported. Recipient Network: Recipient Network is the Network where a number is located after being ported. Recipient Service Provider: A Recipient Service Provider is the Service Provider to whom the number is ported. Routeing Global Title (RGT): A Routeing Global Title (RGT) is, within this document, obtained from a NP DB by using a Called Party Number as input, it is used to route a connection less service towards Recipient Network or/and Recipient Exchange. Routeing Number (RN): A Routeing Number is, within this document, a specific number that is added and used by the networks to route the call. The Routeing Number conveys information usable by the network. If the digits dialled by the user match the digits of a routeing number, the dialled digits should not be interpreted as a routeing number. Service Provider (SP): A Service Provider is an entity that offers services to users involving the use of network resources. The "Service Provider" is understood in this document in a generic way and may have different status according to the service he provides. For example, "Service Provider" refers to a local loop operator in the case of Geographic Numbers, or to a mobile operator in the case of Mobile Numbers, or to a service operator / reseller in the case of Service Numbers. Service Provider Portability for Geographic Numbers: Service Provider Portability for Geographic Numbers is a service that enables customers to resign their subscription with a Service Provider (Donor) and to contract another subscription with another Service Provider (Recipient) without changing their Geographic Number, without changing their location, and without changing the nature of the service offered. This service is also known as GNP and also known as Local Number Portability (LNP). Service Provider Portability for Non geographic Numbers (NGNP): Service Provider Portability for NGNP is a service that enables customers to resign their subscription with a Service Provider (Donor) and to contract another subscription with another Service Provider (Recipient) without changing their Non-geographic Number, and without changing the nature of the service offered. This service is also known as NGNP. TR 101 118 V1.1.1 (1997-11) 11 Service Provider Portability for Pan-European Services: Service Provider Portability for Pan-European Services is a service that enables a user to resign their subscription with their current Pan European Service Provider and subscribe to a competitor without changing their pan European Service Number. Serving Exchange (SE): A Serving Exchange (SE) is, within this document, an Exchange within a Serving Network (SN) that makes a data base (Exchange internal or external) access to retrieve Routeing Number for a call to a Portable Number. Serving Network (SgN): A Serving Network (SgN) is, in this document, a Network that makes a data base (Network internal or external) access to retrieve Routeing Number for a call to a Portable Number, i.e. it determines whether a number has been ported, and, if so, provides an appropriate routeing number. This functionality may be distributed. Signalling Point with Relay(SPR): A SPR consists of both the MTP and SCCP layers of ITU-T Signalling System number 7. Transit Exchange: A Transit Exchange is an exchange between two exchanges, e.g. between the recipient exchange and the donor exchange. Transit Network: Transit Network is a network between two networks, e.g. between the Recipient and the Donor Networks. |
63690b205142be3574b7b253769796a3 | 101 118 | 3.2 Abbreviations | For the purposes of the present document the following abbreviations apply: In the following a number of document internal Symbols and Abbreviations are listed, for not included Symbols and Abbreviations please see "TR: High Level Description of Number Portability. CCPF Call Control Portability Functions CFB Call Forwarding Busy CFNR Call Forwarding No Reply CFU Call Forwarding Unconditional CS Carrier Selection DB Data Base DN Directory Number GNP Geographic Number Portability ETNS European Telephony Numbering Space MSISDN Mobile Station ISDN ISPBX ISDN PBX NGNP Non Geographic Number Portability NPA Numbering Plan Administration NPCP Number Portability Control Point NPDP Number Portability Data Point NPMF Number Portability Management Functions PBX Private Branch Exchange PN Personal Number RN Routeing Number SCP Service Control Point SSP Service Switching Point SSCP Service Switching and Control Point SPR Signalling Point with Relay functions STP Signalling Transfer Point UAN Universal Access Number UPT Universal Personal Telecommunications VPN Virtual Private Network |
63690b205142be3574b7b253769796a3 | 101 118 | 4 Definition of number portability | For the definition and scope of Number Portability please see TR: "High Level Description of Number Portability". TR 101 118 V1.1.1 (1997-11) 12 5 General assumptions and requirements on number portability |
63690b205142be3574b7b253769796a3 | 101 118 | 5.1 Assumptions | The following document internal assumptions have been made: a) that Calling Line Identity (CLI) is required to be transported, with display information, unchanged to Recipient Network; b) that Connected Line Identity (COLI) is required to be transported, with display information, unchanged to Originating Network; c) that Initial Routeing arrangements have been defined and implemented prior the introduction of Routeing based on a Routeing Number; d) it is assumed that Number Portability is not allowed to influence the carrier selection function; e) It is assumed that a NP solution shall not influence functions in Private Branch Exchange (PBX's); f) porting (i.e. reallocation) of complete number blocks is outside this report, works already. For other General assumptions on Number Portability please see TR: " High Level Description of Number Portability". |
63690b205142be3574b7b253769796a3 | 101 118 | 5.2 Requirements | It is required that a High Level Network Architecture for Number Portability allows Network Operator(-s) freedom and privacy in the arrangement of the Network internals as long as the external requirements are fulfilled. External requirements to a Network could be e.g. supplementary service level transparency, post dialling delay, robustness and duration to support porting of Portable Numbers. Number Portability data distribution aspects is also considered, this to allow evolution, smooth portability, safety and privacy. For other Requirements on Number Portability please see TR: "High Level Description of Number Portability". 6 High level evolutionary network models to support call set-up when service provider portability is allowed for geographic numbers |
63690b205142be3574b7b253769796a3 | 101 118 | 6.1 Background information | To ease Routeing tables in the current Public Telecommunications networks (PSTN and ISDN), ITU-T Recommendation E.164 [3] numbers are normally handled and allocated to geographic areas in blocks of e.g. 10.000 subscriber numbers. Each of the blocks are then given to the care of one network provider. The network Operator then either allocates the full 10.000 block or parts of it (e.g. in sub blocks of 1.000 numbers) to a particular Local Exchange (LE), i.e. all subscribers having a subscriber number within a certain block may only be connected to the (local) Exchange handling the number block in question. An other fact has been that a subscriber moving into a new geographic area may only receive a number within the number block(-s) maintained by the new serving operator and new local Exchange to be connected to. The Routeing of a call to subscriber part of PSTN/ISDN, is normally done based on the 10.000 number block the called subscriber number is part of. This traditional principle for Routeing of a call will need to change when introducing Service Provider Portability of Geographic Numbers, since the number series that the called number is part of will no longer have a relation to a particular operators network. TR 101 118 V1.1.1 (1997-11) 13 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.2 General introduction to described models | The following subclauses describes a high level evolutionary model for Service Provider Portability for Geographic Numbers. Non Geographic Numbers within scope of this report, is covered by own chapters. The drawings in the figures and the descriptions are focused on: a) the location in the telecommunications Network where NP information is maintained and stored, i.e. place of DB; b) the location in the telecommunications Network where NP actions are initiated/triggered; c) the location in the telecommunications Network where NP data is retrieved, i.e. place of DB query; d) the location in the telecommunications Network where NP data is used for call Routeing; e) interconnection issues. NOTE: The emphasis on placing the NP DB in the figures is from where the DB access is performed and what triggered the DB access. Despite the figures show the location of the DB within the domain of a particular Network it shall be understood that the DB might very well be located outside that domain, e.g. commonly maintained by a third party. Four main types of Networks are described and identified as involved (depending on the level of NP evolution in the Networks concerned) in setting up a call to a ported subscriber: 1) Originating Network; 2) Transit Network; 3) Donor Network; 4) Recipient Network. NOTE: For most incoming International call the Originating Network will be the Network containing the incoming international gateway. The similar is applied for an incoming call from a PLMN, i.e. that the first incoming GW exchange in the fixed network is regarded as Originating Exchange unless the PLMN has NP DB query capabilities also for Numbers belonging to the fixed network. Despite that management functions not are shown in the figures one should understand that such exist. The management functions might, depending on choices of solutions, be grouped in four areas: A) Management of all the national numbers (i.e. all NP domains in a country); B) Management of a single NP domain (e.g. domain of an Area code); C) Management of NP within a Network providers domain; D) Management of NP within a Network element (e.g. domain of a LE). Depending on solution one, two or all four areas of management functions might exist. The Management functions for Number Portability are modelled and described in later chapters. It shall be understood that other signalling systems than ISUP can be used despite arrows, e.g. IAM and REL, in the figures uses abbreviations that exist in the ISUP protocol. The main discussions around loop and NP DB mismatch detection in run time is described in TR: " Numbering and Addressing for Number Portability". |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3 Call re-routing initiated/performed by donor network | This subclause intends to describe possible High Level NP solutions in a Donor Network. TR 101 118 V1.1.1 (1997-11) 14 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1 Call Re-routed from Donor Network by use of Onward Routei | ng principles |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.1 General Description | The first step/solution discussed for Number Portability is often that the Donor Network maintains the portability information, i.e. the complete Address to both Recipient Network and Exchange, for ported-out numbers and reroute incoming calls to ported-out numbers Onward towards the Recipient Network according to Onward Routeing principles outlined in figure 1. IA M a1 ) IA M a2 ) IA M b ) IA M IA M O r ig in a tin g N e tw o r k C a llin g S u b s c r ib e r D o n o r N e tw o r k R e c ip ie n t N e tw o r k C a lle d S u b s c r ib e r Tr a n s it N e tw o r k ( - s ) ( B ) D B Tr a n s it N e tw o r k ( - s ) ( A ) Figure 1: Call Re-routing to Recipient Network by Onward Routeing principles from Donor Network In figure 1, the Donor Network receives an Incoming call. It then detects that the called number has been ported-out to another network, makes a DB query to retrieve a Routeing Number. It thereafter reroute the call onward towards the Recipient Network using retrieved Routeing information. Option a1 and a2 is valid when Donor Network either has no direct interconnection to Recipient Network or when overflow traffic is placed via Transit Network B. The option b is valid when direct interconnection exists between Donor Network and Recipient Network Despite that the Donor Network acts as a "Onward Routeing" Network to preceding Networks it can use several of the NP techniques within the Network, see later subclauses for this. Please note that the Transit Network(-s) are optional, i.e. direct interconnections connections between Originating Network and Donor Network might very well exist and the same also between Donor Network and Recipient Network. Note also that the Transit Network(-s) A and B can be the same depending on network structure and call case. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.2 Interaction with supplementary services | The service level between Originating Network and Recipient Network is dependent on the level supported by the Donor Network since this scenario/solution requires that the Donor Network have at least the functionality level as the other involved networks, otherwise it will limit the service level for the ported subscribers i.e. some calls might fail with e.g. reason "incompatible destination", e.g. when a caller has requested User-User-1 essential and this service is not supported by Donor Network or that the service is not allowed over operator border to Donor. The use of same inter-exchange protocol within all networks and also that the same interconnection agreements are established between all involved Networks would avoid the interference with supplementary services, but it is highly debatable if possible or even wanted to achieve. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.3 Interaction with IN based services | The same is valid as for interactions with supplementary services, i.e. see previous subclause. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.4 Interaction with carrier selection | No interaction identified, in the scope of this report. TR 101 118 V1.1.1 (1997-11) 15 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.5 Interaction with statistical counters | No interaction identified. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.6 Required forward information transfer between networks | Routeing Information is mandatory in the forward direction, from Donor Network. The Information is needed to inform Transit and Recipient Networks the destination Recipient Network and Recipient Exchange. In addition to the above there might be an interest of having a separate indication that a database lookup, for NP Re- routing, has been performed, this so that the Transit/Recipient Network(-s) easily can recognize/trap incoming calls towards ported subscribers. On the other hand, the reception of Routeing Number might very well be enough indication. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.7 Required backward information transfer between networks | No new NP related data is identified in the backward direction, in the scope of this report. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.8 NP Routeing loop detection issues | No additional loop cases identified, this since this solution only involves retrieval of Routeing information once. TR 101 118 V1.1.1 (1997-11) 16 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.9 Pros | The main advantages with this solution are that: a) the Donor Network remains being responsible for the number series with ported-out numbers, it also continues maintenance of data related to the numbers, this possibly limits the impacts on management systems of Donor; b) the preceding Networks do not need to know if called number has been ported or not, this possibly limits the impacts on management systems of Donor; c) no new forward call indication is needed towards the Donor; d) possibly limited impact on signalling systems; e) additional processing capacity is only required for calls to ported-out numbers. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.1.10 Cons | The main disadvantages with this solution are that: a) the functionality level for the call is dependent on the Donor Network, i.e. calls with essential services (e.g. if U- U-1 essential) not supported by Donor will fail despite supported by other involved Networks. Non essential services will be suppressed if not supported by Donor; b) the Network resources are not used as efficient as for calls to non ported subscribers; c) new Routeing information is needed in forward direction from Donor towards Recipient Network; d) call set-up time will differ between calls to ported-out and not ported numbers; e) the recipient network(-s) should inform donor network(-s) when modifying network internal structure, i.e. it does not allow for privacy for Network Operators; f) there is a risk that the subscriber context capabilities will be exhausted in Donor LE (if NP data is maintained exchange internal) since more numbers or even number blocks should be maintained to continue having same amount of subscribers connected. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2 Call re-routed by drop-back principles from donor network | |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.1 General description | One possible enhancement of the previously described Onward Routeing solution, is that the Donor Network initiates the Re-routing of the call towards the Recipient Network according to "Drop-back" principles outlined in figures 2 and 3 below. Also in this scenario only the Donor Network maintains NP information, i.e. the complete Address to both Recipient Network and Exchange, for ported-out numbers. IA M b ) IA M a1 ) IA M O rig in a tin g N e tw o r k C a llin g S u b s c rib e r D o n o r N e tw o r k R e c ip ie n t N e tw o r k C a lle d S u b sc rib e r Tr a n s it N e tw o r k (-s ) A D B IA M D r o p b. a2 ) IA M Tr a n s it N e tw o r k (-s ) ( B ) L as tin g R e latio n Te m po r ary R e latio n Figure 2: Drop-back with re-routing information and onward re-routing performed by a transit network TR 101 118 V1.1.1 (1997-11) 17 In figure 2, the Donor Network receives an Incoming call. It then detects that the called number has been ported-out to another network. It then determines, on basis of received signalling information, that one of the preceding Networks is capable of handling a "Drop-back" message. It thereafter releases the call with a special indication telling that number is ported-out and Re-routing information is enclosed. The transit network then traps the "Drop-back" and reroute the call onward towards the Recipient Network using received backward information. Option a1 and a2 is valid when Transit Network A either has no direct interconnection to Recipient Network or when overflow traffic is placed via Transit Network B. The option b is valid when direct interconnection exists between Transit Network A and Recipient Network. IA M D r o p b . D ro p b . IA M O r ig in a tin g N e tw o r k C a llin g S u b s c rib e r D o n o r N e tw o r k C a lle d S u b s c r ib e r D B Tr a n sit N e tw o r k (- s) ( A ) b ) IA M a1 ) IA M a2 ) IA M Tr a n sit N e tw o r k (- s) ( B ) L as ting R e latio n Te m p o r ar y R e latio n R e c ip ie n t N e tw o r k c 1 ) IA M c 2 ) IA M Figure 3: Drop-back with re-routing information and onward re-routing performed by the originating network In figure 3, either the Transit Network A has no "Drop-back" capability or determines that the preceding Network has "Drop-back" capability. It therefore lets the Release pass through to Originating Network. The Originating Network, at reception of the Release reroute the call towards Recipient Network. Despite that the Donor Network acts as a "Call Drop-back" Network to preceding Networks it can use several of the NP techniques within its Network, see later subclauses for this. Please note that the Transit Networks are optional, i.e. direct connections between Originating Network and Donor Network might very well exist but on the other hand the Transit Network might exist (case a1 and a2) between the Onward Routeing (Transit or Originating) Network and Recipient Network. A further evolution of the "Drop-back" principle outlined in the figure 2 is that the Drop-back message is sent back to the Originating Network as in figure 3. This evolution is mainly of interest if the Originating Network has direct interconnections to other Networks than the Transit Network used in the call attempt to the Donor Network. Option a1 and a2, in figure 3, is valid when Originating Network either has no direct interconnection to Recipient Network or when overflow traffic is placed via Transit Network B. The option b, in figure 3, is valid when direct interconnection exists between Originating and Recipient Networks. The option c1 and c2, in figure 3, is required when Carrier Selection is valid for the call i.e. the Originating Networks reuses the Carrier Selection information after reception of Drop-back message. It could be debated if a selected carrier (e.g. TN A in figure 3) is allowed/recommended to transport the drop-back to Originating Network, but it has no option if it has no redirect on "Drop-back" capability. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.2 Interaction with supplementary services | A risk of Interference exists for essential supplementary services since the Donor Network should be reached to get redirection information, i.e. call might be released prior reaching Donor Network. Interference might exist also for non essential services if the drop-back is not sent back to the Originating exchange. A way out is that the all involved networks have same interconnection agreements, but this might not be enough e.g. the same signalling systems should also be used within all networks in the case call should travel until Donor Local Exchange to get Routeing Information. The "Drop-back" should not be sent through the Exchange that has performed a Call forwarding service like CFU, Call Forwarding Busy (CFB) or Call Forwarding No Reply (CFNR) etc. this to avoid unwanted interference with these kind of services. TR 101 118 V1.1.1 (1997-11) 18 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.3 Interaction with IN based services | The "Drop-back" should not be sent through the Service Switching Point (SSP) that has performed an IN service like PN, Universal Personal Telecommunications (UPT), Virtual Private Network (VPN), Universal Access Number (UAN), etc. this to avoid unwanted interference with these kind of IN based services. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.4 Interaction with carrier selection | An identified Interaction with carrier selection is described as option c1 and c2 in figure 3. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.5 Interaction with statistical counters | Standards for Circuit quality counters/statistics should be mollified to handle Drop-back conditions, otherwise alarms might come for functioning circuits/destinations when number of calls to ported-out numbers are high. I.e. a drop-back message should not be handled as an ordinary release before answer. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.6 Required forward information transfer between networks | In the forward direction (IAM), towards Donor, there is a need of an indication telling whether or not "Re-routing on Drop-back" is supported or not, this to inform succeeding Network if it should do the Re-routing or if the release can be sent backwards i.e. "Drop-back" can only be performed when a preceding Network has functionality to perform Re- routing based on returned Re-routing information. An option, not requiring the indication, is the use of bilateral agreements, e.g. a route indicator telling if preceding Network has the QoR capability. An other option, not requiring the indicator, is a homogeneous Network, i.e. all interconnection exchanges has "Re- routing on Drop-back" capability and that this can be assumed by, e.g. Donor. What is described in subclause 6.3.1.4.1 is valid also here. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.7 Required backward information transfer between networks | Re-routing information should be sent in Backward direction, from Donor, to inform preceding Networks about the Address to the Recipient Network and Recipient Exchange. Possibly special release indication "Drop-back" is also needed to allow circuit quality counters be correctly stepped. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.8 NP routeing loop detection issues | No additional loop cases identified, this since this solution only involves retrieval of Routeing information once. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.9 Pros | The main advantages with this solution are that: a) the Donor Network remains being responsible for the number series with ported-out numbers, it also continues maintenance of data related to the numbers, this possibly limits the impacts on management systems of Donor; b) the preceding Networks do not need to know if called number has been ported or not, this possibly limits the impacts on management systems of Donor; c) more efficient utilization of network resources, than in the Onward Routeing case; d) if the drop-back is sent until Originating Network also the accounting will be same as for calls to non ported subscribers; e) some additional non essential supplementary services might work (still problems exist with the essential ones), compared to the Onward Routeing case, this thanks to less networks involved (e.g. no Donor) in the final call set- up; TR 101 118 V1.1.1 (1997-11) 19 f) additional processing is only required for calls to ported subscribers. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.2.10 Cons | The main disadvantages with this solution are that: a) the functionality level for the call is dependent on the Donor Network, i.e. calls with essential services (e.g. if U- U-1 essential) not supported by Donor will fail despite supported by other involved Networks; b) the Network resources are not used as efficient as for calls to non ported subscribers; c) new Routeing information is needed towards Donor Network; d) new Routeing information is mandatory in forward direction from Re-routing Network; e) adaptations are required to ensure that Circuit quality counters will not become more or less useless when the percentage of calls to ported numbers is high; f) the recipient network(-s) should inform donor network(-s) when modifying internal network structure, i.e. it does not allow for privacy for Network Operators; g) there is a risk that the subscriber context capabilities will be exhausted in Donor LE (if NP data is maintained exchange internal) since more numbers or even number blocks should be maintained to continue having same amount of subscribers connected. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3 Call re-routing initiated by "Query on Release (QoR)" pri | nciples from donor network |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.1 General description | A similar case as the previously described "Drop-back" principle is when the preceding Network to Donor initiates NP actions, i.e. a NP DB query, at reception of a Release Message, this case is often referred to as "Query on Release (QoR)", see figure 4 and 5. The release message contains a certain indication (e.g. special cause value or Diagnostics Information) telling that the called number is ported-out. Optionally no special indication is received in the release (REL) message, this case is valid when Donor network maintains no data for ported-out numbers. The failure reason "destination incompatible" (and similar other failure reasons) should be included to trap cases where the Donor Network might be of lower functionality level than the Originating/Transit and an essential service was used, i.e. the DB should be queried to determine in the number is ported-out, if so then the call is redirected to Recipient. IA M R E L a1 ) IA M a2 ) IA M b ) IA M IA M C a llin g S u b s c rib e r D o n o r N e tw o rk R e c ip ie n t N e tw o rk C a lle d S u b sc rib e r Tr a n sit N e tw o rk (A ) D B Tr a n sit N e tw o rk (- s) (B ) O rig in a tin g N e tw o rk L as ting R e latio n Te m p o rar y R e latio n Figure 4: Query on release by transit network In figure 4, the Donor Network receives an Incoming call. It then either detects that the called number has been ported- out to another network or optionally only that the number is just vacant in this network. It then determines that one of the preceding Networks has QoR capability by looking at received signalling information. It thereafter releases the call with or without a special indication telling that called number is ported-out. The transit network then traps the Release, determines that preceding network has no QoR capability, makes a NP data base query and reroute the call onward towards the Recipient Network. In this scenario the Transit Network has access to a NP DB with the complete Address to both Recipient Network and Exchange, at least for ported-out numbers. TR 101 118 V1.1.1 (1997-11) 20 Option a1 and a2, in figure 4, is valid when Transit Network A either has no direct interconnection to Recipient Network or when overflow traffic is placed via Transit Network B. The option b, in figure 4, is valid when direct interconnection exists between Transit Network A and Recipient Network. Please note in this case that the DB query might take place also in the Originating Network, i.e. that the DB could also exist in the origination Network as described in the figure 6 below. IA M R E L R E L IA M O rig in a tin g N e tw o rk C a llin g S u b s c rib e r D o n o r N e tw o rk C a lle d S u b sc rib e r Tr a n sit N e tw o rk (- s) (A ) b ) IA M a1 ) IA M a2 ) IA M Tr a n sit N e tw o rk (- s) (B ) L as ting R e latio n Te m p o rar y R e latio n R e c ip ie n t N e tw o rk c 1 ) IA M c 2 ) IA M D B Figure 5: Query on release by originating network In figure 5, either the Transit Network A has no QoR query capability or determines that the preceding Network has QoR capability. It therefore lets the Release pass through to Originating Network. The Originating Network, at reception of the Release queries its NP data base and reroute the call towards Recipient Network. In this scenario the Originating Network has access to a NP DB with the complete Address to both Recipient Network and Exchange, at least for ported- out numbers. It shall be noted that despite the Number Portability DB is drawn within the domain of the Transit and Originating Networks, it shall be understood that the actual physical location of the DB might be within any of the Networks or even outside the Networks, e.g. maintained by a third party. The key issue is what triggers the query and in which of the Networks the query is performed. A further evolution of the "Query on Release" principle outlined in the figure 4 is that the Release message is sent back to the Originating Network as in figure 5, this evolution is mainly of interest if the Originating Network has direct connections to other Networks than the Transit Network currently used. Option a1 and a2, in figure 5, is valid when Originating Network either has no direct interconnection to Recipient Network or when overflow traffic is placed via Transit Network B. The option b, in figure 5, is valid when direct interconnection exists between Originating and Recipient Networks. The option c1 and c2, in figure 5, is required when Carrier Selection is valid for the call i.e. the Originating Networks reuses the Carrier Selection information after querying NP DB. It could be debated if a selected carrier (e.g. TN A in figure 5) is allowed/recommended to transport the "Drop-back" to Originating Network, but if it has no option if it has no redirect on "Drop-back" capability. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.2 Interaction with supplementary services | Interference risk exists for essential supplementary services in the case that Transit Network should be reached to get redirection information. Interference risk might also exist for non essential services in the case that release message is not sent back to the Originating exchange. No interference with supplementary services in the case that release message is returned back to the Originating local exchange and query is also made when release with "incompatible destination" is received. The "Release" should not be sent through the Exchange that has performed a Call forwarding service like CFU, CFB or CFNR etc. this to avoid unwanted interference with these kind of services. In the number is found out to be really vacant, after the DB query, then a special release indication should be sent to indicate this. This to avoid DB query in preceding networks. TR 101 118 V1.1.1 (1997-11) 21 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.3 Interaction with IN based services | The "Release" should not be sent through the SSP that has performed an IN service like PN, UPT, VPN, UAN, etc. this to avoid unwanted interference with these kind of IN based services. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.4 Interaction with carrier selection | An identified Interaction with carrier selection is described as option c1 and c2 in figure 6. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.5 Interaction with statistical counters | Standards for Circuit quality counters/statistics should be mollified to handle QoR conditions, otherwise alarms might come for functioning circuits/destinations when number of calls to ported-out numbers are high. I.e. a drop-back message should not be handled as an ordinary release before answer. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.6 Required forward information transfer between networks | In the forward direction there is a need of an indication telling whether or not Query on Release (QoR) is supported or not, this to inform succeeding Network if it should do the Query (and redirection) or if the release can be sent backwards. An option to this forward call indication, is incoming route data according to bilateral agreements principles (similar as for the drop-back case). What is described in subclause 6.2.1.4.1 is valid also here. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.7 Required backward information transfer between networks | New Re-routing information "Ported-out number" is sent backwards (e.g. by use of a special cause value or Diagnostics Information), i.e. when the Donor Network keeps some limited data also for ported-out numbers so that differing (compared to really vacant numbers) release information can be given when calls are made to these subscribers. This will reduce the number of DB queries made when few numbers are ported. Optionally the new backward information above is not needed, i.e. when the Donor Network keeps no data for ported- out numbers and only returns "vacant number" also for calls to these numbers. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.8 NP Routeing loop detection issues | No additional loop cases identified, this since this solution only involves retrieval of Routeing information once. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.9 Pros | The main advantages with this solution are that: a) it might allow the Donor Network to discontinue maintaining Routeing information for ported-out numbers; b) more efficient utilization of network resources, than in the Onward Routeing case; c) If the release is sent until Originating Network also the accounting will be same as for calls to non ported subscribers; d) Both non essential and essential supplementary services might work , this in the case that the Release is sent to the Originating Network; e) call set-up no longer dependent on Donor and might not be on Transit either; f) Additional processing capacity only required for calls to ported-out (but optionally also to vacant) numbers. TR 101 118 V1.1.1 (1997-11) 22 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.3.3.10 Cons | The main disadvantages with this solution are that: a) new Routeing information is needed towards Donor Network; b) new Routeing information is needed in forward direction from Re-routing Network; c) adaptations are required to ensure that Circuit quality counters will not become more or less useless when the percentage of calls to ported numbers is high; d) donor might need to maintain an indication for ported-out numbers; e) the recipient network(-s) should inform other network(-s) when modifying network internal structure, i.e. it does not allow for privacy for Network Operators. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4 Call re-routing initiated/performed by transit network prio | r to donor network This subclause intends to describe possible High Level NP solutions in a Transit Network prior to a Donor Network. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.1 Re-routing initiated by reception of re-routing informati | on from succeeding network Re-routing according to "Drop-back" principles when drop-back can not be returned to preceding Network is already described in previous subclause. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.2 Re-routing initiated by reception of "number ported-out i | nformation" from succeeding network Re-routing according to "Query on Release (QoR)" principles is already described in previous subclause. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3 Re-routing initiated by "all call query one step" princip | les |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.1 General description | A further evolution of NP solutions, compared to "Drop-back" and "Query on Release" principles, in a Transit Network is the principle of always query a NP Data Base prior Routeing the call towards Donor/Recipient Network, i.e. Re- routing according to "all call query one step" principles as outlined in figure 6 below. In this scenario the Transit Network (TN) has access to a NP DB with the complete Address to both Recipient Network and Exchange, at least for ported-out numbers. Recipient Network need not do any own query in this scenario since complete address is obtained by TN. IA M a1 ) IA M a2 ) IA M b ) IA M C a llin g S u b s c rib e r D o n o r N e tw o rk R e c ip ie n t N e tw o rk C a lle d S u b sc rib e r Tr a n sit N e tw o rk (A ) D B Tr a n sit N e tw o rk (- s) (B ) O rig in a tin g N e tw o rk L as ting R e latio n Te m p o rar y R e latio n Figure 6: "All call Query" by transit network. TR 101 118 V1.1.1 (1997-11) 23 As can be seen from the figure 6 above the Donor Network is not involved at all in the call set up to the ported subscriber. Calls might be onward routed back (i.e. tromboned), from Transit A, to Originating network in the case that Originating and Recipient networks are the same. A way out of this is that Originating network keeps track of ported-in subscribers and only uses Transit for Inter-network calls. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.2 Interaction with supplementary services | Interference risk exists, i.e. call might not be delivered, for calls with essential supplementary services since the Transit Network should be reached to get redirection information. Interference risk might also exist for non essential services if the Originating Network for calls to non ported subscribers uses a direct interconnection to the Recipient Network i.e. the functionality level between Originating and Transit Network A and B might differ according to type of interconnection and bilateral agreements. Calls with not supported non essential services will still be delivered, but the not supported service(-s) are suppressed. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.3 Interaction with IN based services | No interference/impact identified. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.4 Interaction with carrier selection | If calling party has requested carrier selection then Transit Network(A) would be the requested carrier. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.5 Interaction with statistical counters | No interference/impact identified. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.6 Required forward information transfer between networks | What is described in subclause 6.2.1.4.1 is valid also here. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.7 Required backward information transfer between networks | No new NP related information is identified in the backward direction for call Routeing purposes. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.8 NP routeing loop detection issues | No additional loop cases identified, since this solution only involves retrieval of Routeing information once only, even for calls over Operator borders. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.9 Pros | The main advantages with this solution are that: a) it allows the Donor Network to discontinue maintaining data for subscriber numbers no longer in response of; b) more efficient utilization of Network resources, than in the Onward Routeing case; c) shorter call set-up time to poted-out subscribers, than in the QoR; d) some additional supplementary services might work (less Networks involved); e) statistical circuit quality counters will work as today thanks no release involved prior redirection; f) Donor Network will not need to consider processing capacity for incoming calls to ported-out numbers; g) equal treatment of calls to both ported and not ported subscribers; h) calls to really vacant subscribers are trapped prior reaching Donor, this saving load (in Donor) and possible accounting costs (in Transit A) for non successful calls. TR 101 118 V1.1.1 (1997-11) 24 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.4.3.10 Cons | The main disadvantages with this solution are that: a) the functionality level for the call is dependent on the Transit Network, e.g. calls with essential services (e.g. if U-U-1 essential) not supported by Transit will fail despite supported by other Originating and Recipient Networks. Non essential services might not work; b) the Network resources might not be used as efficient as for calls to non ported subscribers; c) new Routeing information is needed in forward direction from Re-routing Network, i.e. Transit A; d) longer call set-up time for calls to not ported subscribers, than in the onward Routeing, Query on Release and Drop-back cases; e) additional processing capacity (the query) is needed for all calls; f) tromboning to Transit for intra network calls, compared to query performed in Originating Network; g) the recipient network(-s) should inform other network(-s) when modifying internal network structure, i.e. it does not allow for privacy for Network Operators; h) large processing capacity required in DB since all calls will require DB query. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5 Call re-routing performed by originating network | This subclause intends to describe possible High Level NP solutions in an Originating Network. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.1 Re-routing initiated by reception of re-routing informati | on from succeeding network Re-routing according to "Drop-back" principles when drop-back can not be forwarded to preceding Network is already described in previous subclause and is valid also for Originating Networks since Drop-back will not be returned to subscriber. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.2 Re-routing initiated by reception of "number ported-out i | nformation" from succeeding network Re-routing according to "Query on Release (QoR)" principles is already described in previous subclause and is also valid for Originating Networks. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3 Re-routing initiated by "All call query one step" princip | les |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.1 General description | Same principles are valid as for Transit Network but for clarification the "All call query" principles is shown in the figure 7 below. In this scenario the Originating Network has access to a NP DB with the complete Address to both Recipient Network and Exchange, at least for ported-out numbers. This implies that only one NP DB lookup needs to be performed to complete the call. TR 101 118 V1.1.1 (1997-11) 25 b ) IA M a1 ) IA M a2 ) IA M O rig in a tin g N e tw o rk C a llin g S u b s c rib e r D o n o r N e tw o rk R e c ip ie n t N e tw o rk C a lle d S u b sc rib e r Tr a n sit N e tw o rk D B L as ting R e latio n Te m p o rar y R e latio n Figure 7: All call Query by Originating Network As can be seen in the figure 7, the Donor Network is not involved in the call set-up at all, however optionally the Transit Network (see case a1 and a2 above) might be transiting the call to the Recipient Network. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.2 Interaction with supplementary services | No interactions with supplementary services are foreseen if DB query is made in the Originating Local Exchange. Otherwise there might be some interference's with e.g. with services having subscriber attribute(-s) normally only available in the Originating LE. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.3 Interaction with IN based services | No interference/impact identified. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.4 Interaction with carrier selection | This case is not necessarily valid if calling party has requested carrier selection, i.e. If calling party has requested carrier selection then Originating Network would not need to do any NP DB query, instead the call can be routed directly to Transit Network which then is responsible for further Routeing towards recipient. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.5 Interaction with statistical counters | No interference/impact identified. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.6 Required forward information transfer between networks | Re-routing information should be sent over Network borders to inform about both the Recipient Network and Recipient Exchange. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.7 Required backward information transfer between networks | No new NP related information is identified in the backward direction for call Routeing purposes. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.8 NP Routeing loop detection issues | No additional loop cases identified, since this solution only involves retrieval of Routeing information once only, even for calls over Operator borders. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.9 Pros | The main advantages with this solution are that: a) it allows the Donor Network to discontinue maintaining data for subscriber numbers no longer in response of; b) as efficient utilization of Network resources, as for calls to non ported numbers; c) shorter call set-up time, than in the QoR case to ported subscribers; TR 101 118 V1.1.1 (1997-11) 26 d) all supplementary services will work, as for calls to non ported numbers, thanks to no dependency on other networks (than used for other calls) to set up the call to recipient; e) Originating Network has full control over call Routeing; f) Statistical circuit quality counters will work as today thanks no release involved prior redirection; g) Donor Network will not need to consider processing capacity for incoming calls to ported-out numbers; h) equal treatment of calls to both ported and not ported subscribers; i) calls to really vacant subscribers are trapped already in Originating, this saving load (in both Transit and Donor) and possible accounting costs (in Originating) for non successful calls; j) no interference with Carrier Selection; k) robust network since no dependency on other networks in getting Routeing information for calls to ported subscribers. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.5.3.10 Cons | The main disadvantages with this solution are that: a) NP related Routeing information is mandatory in forward direction from Re-routing (i.e. Originating) Network; b) longer call set-up time for calls to not ported subscribers, than in the Onward Routeing, Query on Release and Drop-back cases; c) additional processing capacity (the query) is needed for all calls; d) large processing capacity required in DB since all calls will require DB query; e) more networks required to invest in DB techniques; f) the recipient network(-s) should inform other network(-s) when modifying internal network structure, i.e. it does not allow for privacy for Network Operators. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6 Call re-routing to recipient performed by a two step number | translation principle |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.1 General description | This subclause intends to describe a High Level NP solution when a two step number translation principle is used. The first step include a number translation to obtain partial Routeing information indicating recipient Network (optionally also point of Interconnection) and where the second step obtains the complete Routeing information indicating also the Recipient Exchange according to the following: 1 retrieval of partial Routeing information indicating recipient network only (optionally also point of Interconnection). This step can either be initiated by: a) Onward Routeing by Donor (only calls to ported-out numbers); b) Drop-back from Donor (only calls to ported-out numbers); c) Query on Release (only calls to ported-out numbers); d) "all call Query" by Transit (all calls to portable numbers); e) "all call Query" by Originating (all calls to portable numbers), 2 retrieval of complete Routeing information indicating also recipient Exchange. TR 101 118 V1.1.1 (1997-11) 27 Performed by Recipient Network either at reception of an incoming call with only partial Routeing Information or for all incoming calls (to portable number blocks). The figure 8 below shows a NP solution where the Donor Network detects that the called number has been ported-out, makes a NP DB query on the received CdPN to retrieve a partial Routeing Number to address the Recipient Network. It then routes the call onward towards the Recipient Network either directly or via Transit Network(-s). IA M a1 ) IA M a2 ) IA M b ) IA M IA M O r ig in a tin g N e tw o r k C a llin g S u b s c r ib e r D o n o r N e tw o r k R e c ip ie n t N e tw o r k C a lle d S u b s c r ib e r Tr a n s it N e tw o r k ( - s ) ( B ) D B Tr a n s it N e tw o r k ( - s ) ( A ) D B Figure 8: Onward routeing by donor combined with query by recipient network The figure 9 below shows a NP solution where the Donor Network detects that the called number has been ported-out, makes a NP DB query on the received CdPN to retrieve a partial Routeing Number to address the Recipient Network. It then returns a release message which is sent all the way to Originating Network which uses the received Routeing Number, routes the call towards the Recipient Network either via Transit Network(-s) or directly. IA M D r o pb . D r o pb . IA M O rig in a tin g N e tw o rk C a llin g S u b s c rib e r D o n o r N e tw o rk C a lle d S u b sc rib e r Tr a n sit N e tw o rk (- s) (A ) b ) IA M a1 ) IA M a2 ) IA M Tr a n sit N e tw o rk (- s) (B ) L as ting R e latio n Te m p o rar y R e latio n R e c ip ie n t N e tw o rk c 1 ) IA M c 2 ) IA M D B D B Figure 9: Drop-back combined with query by recipient network The figure 10 below shows a NP solution where the Donor Network detects that the called number has been ported-out. It then returns a release message, with a special indication "ported" The release message is sent all the way to Originating Network. The Originating Network makes a NP DB query on the CdPN to retrieve a partial Routeing Number to address the Recipient Network, routes the call towards the Recipient Network either via Transit Network(-s) or directly. IA M R E L R E L IA M O rig in a tin g N e tw o rk C a llin g S u b s c rib e r D o n o r N e tw o rk C a lle d S u b sc rib e r Tr a n sit N e tw o rk (- s) (A ) b ) IA M a1 ) IA M a2 ) IA M Tr a n sit N e tw o rk (- s) (B ) L as ting R e latio n Te m p o rar y R e latio n R e c ip ie n t N e tw o rk c 1 ) IA M c 2 ) IA M D B D B Figure 10: Query on release combined with query by recipient network The figure 11 below shows a NP solution where the Originating Network routes the call towards the Donor, the Transit makes a NP DB query (e.g. for all outgoing calls) on the CdPN to retrieve a partial Routeing Number to address the Recipient Network. It then routes the call towards the Recipient Network either via another Transit Network(-s) or directly. TR 101 118 V1.1.1 (1997-11) 28 IA M a1 ) IA M a2 ) IA M b ) IA M C a llin g S u b s c rib e r D o n o r N e tw o rk R e c ip ie n t N e tw o rk C a lle d S u b sc rib e r Tr a n sit N e tw o rk (A ) D B Tr a n sit N e tw o rk (- s) (B ) O rig in a tin g N e tw o rk D B Figure 11: "All call query" by transit network combined with query by recipient network The figure 12 below shows a NP solution where the Originating Network makes a DB query on the CdPN to retrieve a partial Routeing Number to address the Recipient Network, routes the call towards the Recipient Network either via Transit Network(-s) or directly (option b). b) IAM a1 ) IAM a2 ) IAM Originating Network D onor Network Rec ipient Network C alled S ubsc riber Transit Network(-s) D B C alling Subsc riber D B Figure 12: "All call query" by originating network combined with query by recipient network. For the figures 8-12, the recipient network either traps all incoming calls or traps calls received with a special indication "ported call" or with a partial Routeing number. It then makes a query to "own" NP DB to obtain a complete Routeing number to address the recipient exchange. In all the above solutions the NP DB outside the Recipient network contains Routeing Information to address the recipient Network only. This principle has two main advantages: a it allows for privacy of the recipient network; b) less DB updates are needed, since other Network Data Bases need not be updated e.g. when the recipient Network operator performs internal restructuring of its Network. For all solutions, the Routeing number is enclosed in the forward message to avoid NP DB query in Transit Network(-s) and to enable trapping of NP DB mismatch by Recipient Network. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.2 Interaction with supplementary services | Interactions with supplementary services are depending on the first Routeing step and are described in previous subclauses. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.3 Interaction with IN based services | No interference/impact identified. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.4 Interaction with carrier selection | Interactions with carrier selection is depending on the first Routeing step and are described in previous subclauses. TR 101 118 V1.1.1 (1997-11) 29 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.5 Interaction with statistical counters | Interactions with statistical counters is depending on the first Routeing step and are described in previous subclauses. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.6 Required forward information transfer between networks | Forward Routeing information need to be sent over Network borders. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.7 Required backward information transfer between networks | NP related backward information is depending on the first Routeing step and are described in previous subclauses. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.8 NP routeing loop detection issues | Some loop cases are identified, since this solution involves retrieval of Routeing information two times, for a call over Network borders. Only one retrieval required if Originating and Recipient Networks are the same. Loop and NP DB mismatch detection can easily be performed by recipient network by comparing received Routeing Number (indicating recipient Network ID i.e. own network) with the Routeing Number received from the own NP DB. I.e. the retrieved Routeing number should not indicate other network than own. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.9 Pros | The main advantages with this solution are that: a) network operators need not inform others when making changes in their internal network, i.e. privacy of network internals is maintained; b) less NP DB updates are needed. In addition to the above listed pros, please see relevant subclauses for each of the first step Routeing options. |
63690b205142be3574b7b253769796a3 | 101 118 | 6.6.10 Cons | The main disadvantages with this solution are that: a) additional processing capacity (the query) is needed for all incoming calls to Recipient network. In addition to the above listed cons, please see relevant subclauses for each of the first step Routeing options. TR 101 118 V1.1.1 (1997-11) 30 |
63690b205142be3574b7b253769796a3 | 101 118 | 6.7 Call re-routing performed by using "all call query all invo | lved networks" principles |
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