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977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.1.1.3 CMTS MAC Domain | 5.2.1.1.3.0 General A DOCSIS MAC Domain is a logical sub-component of a CMTS that is responsible for implementing all DOCSIS functions on a set of downstream channels and upstream channels. A CMTS MAC Domain contains at least one downstream channel and at least one upstream channel. A MAC Domain is responsible for send... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.1.2 CM Model | A CM is a DOCSIS network element that forwards (bridges) layer-2 traffic between a Radio Frequency Interface (RFI) and one or more Customer Premises Equipment ports. |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.2 Downstream Convergence Layer | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.2.1 Control Channel | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.2.1.1 PLC | The PHY Link Channel (PLC) is a narrowband signalling channel located within the downstream OFDM channel. PLC has been designed to enable "blind" channel acquisition, to provide downstream timing reference and scattered pilot pattern synchronization as well as to aid in energy management protocol and PNM symbol capture... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.2.1.2 NCP | The Next Codeword Pointer (NCP) is a portion of the downstream OFDM channel which is dedicated to carry information about the mapping of FEC codewords to subcarriers within a symbol. NCP is generally considered a part of the Downstream Convergence Layer. [12] includes a detailed description of the NCP. The NCP referenc... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.2.2 Profiles | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.2.2.1 Multiple Downstream Profile Support in OFDM Channels | In order to leverage this new PHY to its maximum benefit, DOCSIS 3.1 allows different subcarriers to use different modulation orders. This is referred to as variable bit-loading on the channel. A downstream profile defines the modulation order (i.e. bit loading) on each carrier. In order to account for varying downstre... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.3 OFDMA Upstream | OFDMA is a new type of upstream channel for DOCSIS 3.1. OFDMA upstream channels can span more spectrum than TDMA or S-CDMA upstream channels. OFDMA upstream channels use LDPC for Forward Error Correction and have other attributes specific to Orthogonal Frequency Division Multiplexing technology. OFDMA channels utilize ... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4 QoS | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.0 Overview | This clause provides an overview of the QoS protocol mechanisms and their part in providing end-to-end QoS. Some of the Quality of Service related features described in the present document include: • Packet Classification and Flow Identification • Service Flow QoS Scheduling with a set of QoS Parameters, including: - ... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.1 Individual and Group Service Flows | Downstream Service Flows may be distinguished by whether they provide service to an individual CM or a group of CMs: • Individual Service Flows are defined as Service Flows created by the Registration process of a single CM or a Dynamic Service Addition process to a single CM. • Group Service Flows are created by the C... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.2 Hierarchical QoS | HQoS provides an optional, intermediate level in the scheduling hierarchy between Service Flows and channels/BGs, and introduces aggregate QoS treatment. HQoS provides either aggregating unicast Service Flows associated with a single CM, or aggregating Service Flows associated with multiple CMs but typically sharing so... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.3 AQM | DOCSIS 3.1 provides Active Queue Management by default on all upstream Best Effort and Non-Real-Time Polling Service Flows, and on all Downstream Service Flows. Active Queue Management significantly reduces buffering latency in the CM (for upstream) and CMTS (for downstream) during heavy traffic loads, without signific... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.4 Channel Bonding | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.4.1 Downstream Channel Bonding | In order to provide increased peak downstream data rates to customers, while maintaining interoperability with legacy CMs, DOCSIS 3.0 introduced a mechanism by which the CMTS dynamically distributes downstream packets over a set of downstream channels for delivery to a single CM. For DOCSIS 3.1, a downstream channel in... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.4.2 Upstream Channel Bonding | 5.2.4.4.2.0 General Cable operators would like to be able to provide higher upstream bandwidth per user in order to compete with FTTx offerings and provide services to small businesses. Cable provides increased upstream throughput from a single user or group of users through transmission on multiple upstream channels s... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.5 Upstream Time and Frequency Multiplexing | In addition to upstream channel bonding, DOCSIS 3.1 also supports simultaneous Time and Frequency Division Multiplexing (TaFDM) between SC-QAM and OFDMA channels. This implies both: • OFDMA and SC-QAM can simultaneously operate on separate frequencies • OFDMA and SC-QAM can also operate on the same frequencies, divided... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.4.6 Autonomous Load Balancing | Similar to DOCSIS 3.0 CMTS, the DOCSIS 3.1 CMTS supports autonomous load balancing of CMs. In DOCSIS 2.0 a mechanism was defined in which the CMTS could be configured with certain load balancing group information which would be used by the CMTS in order to balance load across a number of channels in the case where mult... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.5 Multicast Operation | DOCSIS provides support for IP Multicast with features such as Source Specific Multicast [48], Quality of Service support for multicast traffic, IPv6 multicast, and bonded multicast. These enhanced IP Multicast features enable cable operators to offer various IP Multicast-based multimedia services, such as Internet Pro... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.6 Network and Higher Layer Protocols | At the Network Layer DOCSIS requires the use of Internet Protocol version 4 and version 6 for transporting management and data traffic across the HFC link between the CMTS and the CM. As described above the CMTS could perform MAC Layer bridging or Network Layer routing of data traffic, while the CM only performs MAC la... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.7 CM and CPE Provisioning and Management | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.7.1 Initialization, Provisioning and Management of CMs | During initialization, the CM goes through a number of steps before becoming fully operational on the DOCSIS network. The full initialization sequence is detailed in clause 10, but at a high level comprises four fundamental stages: 1) topology resolution and physical layer initialization; 2) authentication and encrypti... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.7.2 Initialization, Provisioning and Management of CPEs | DOCSIS assumes the use of DHCP for provisioning of CPE devices. To that end the CMTS supports a DHCP relay agent which allows the operator to associate a CPE IP Address request with the subscriber Cable Modem MAC Address. This feature is also used as the basis of a mechanism that prevents spoofing of IP addresses. DOCS... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.8 Enhanced Support for Timing Protocol | The DOCSIS Time Protocol (DTP) is a set of techniques coupled with extensions to the DOCSIS signalling messages which allow the timing and frequency system of DOCSIS to be interfaced to external timing protocols with high accuracy. The primary application of DTP is to provide precise frequency and time to an external s... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.9 Energy Management | DOCSIS 3.0 introduced Energy Management (EM) 1x1 mode, where the CM uses a single upstream and a single SC- QAM downstream channel. The CM monitors HFC network usage, compares it to the EM entry and exit thresholds. The CM requests entry into and exit out of the EM 1x1 mode via EM-REQ messages. The CMTS then commands t... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.10 Relationship to the Physical HFC Plant Topology | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.10.1 RF Topology Configuration | The basic connectivity principles for upstream and downstream connectivity between a CMTS and a CM are explained in Annex N. This portion of the document explains how DOCSIS relates the HFC Plant Topology to CM Service Groups, MAC Domains, and Bonding Groups. CMTSs and CMs are interconnected by an RF combining and spli... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.10.2 Frequency Assignment | The topology database is configured at the CMTS to enable it to maintain frequency isolation for multiple channels reaching the same fibre node. During configuration, the CMTS will enforce that RF Channels reaching the same fibre node have different frequencies. ETSI ETSI TS 103 311-3 V1.1.1 (2017-02) 73 The CMTS uses ... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.11 Cable Modem Service Group (CM-SG) | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.11.0 Overview | A "Cable Modem Service Group" (CM-SG) is formally defined as the complete set of CMTS channels-both upstream and downstream-that reach a single cable modem. In an HFC deployment, all CMs reached by the same fibre node are reached by the same set of channels. Furthermore, in most HFC deployments, each fibre node has a d... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.11.1 MAC Domain Channel Assignment | An operator configures each upstream and downstream channel of a CMTS into a MAC Domain. In a frequency/space diagram, a MAC Domain can be represented by a "barbell" that encloses the downstream channels of the MAC Domain on one side and the upstream channels of the MAC Domain on the other side. Figure 5.11 shows a typ... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.11.2 Multiple MAC Domains per Fibre Node | For simplicity, it is recommended that all DOCSIS channels from a CMTS reaching a fibre node be configured into the same MAC Domain. It may be desired, however, to define separate sets of downstream and upstream channels that reach the same fibre node into different MAC Domains in order to provide separate services. Fo... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.11.3 MAC Domain Downstream and Upstream Service Groups | The term "MAC Domain Downstream Service Group" (MD-DS-SG) refers to the set of downstream channels from the same MAC Domain that reaches a fibre node. In many cases, an operator will configure all downstream channels reaching a fibre node to the same MAC Domain, in which case an MD-DS-SG corresponds to a DS-SG from the... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.11.4 Channel Bonding Topology Considerations | A "Provisioned" Bonding Group is a configured set of downstream or upstream channels on the same MAC Domain that reach at least one fibre node in common. Figure 5.13 takes the Service Groups and MAC Domains defined in earlier figures and overlays a variety of provisioned Downstream Bonding Groups (DBG) and Upstream Bon... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 5.2.12 CMTS Downstream Service Model Example | The model for downstream forwarding with bonding groups is an extension of the MAC service model for the CMTS. The model remains that downstream bonded service is offered by MAC Domains, and that the "CMTS Forwarder" is responsible for forwarding packets from a Network Side Interface (NSI) to the MAC Service Access Poi... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6 Media Access Control Specification | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1 Introduction | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.1 Overview | This clause describes version 3.1 of the DOCSIS MAC protocol. Some of the highlights of the DOCSIS MAC protocol include: • Bandwidth allocation controlled by CMTS • A stream of minislots in the upstream • Dynamic mix of contention- and reservation-based upstream transmit opportunities • Bandwidth efficiency through sup... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2 Definitions | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.1 MAC-Sublayer Domain | A MAC-sublayer domain is a collection of upstream and downstream channels for which a single MAC Allocation and Management protocol operates. Its attachments include one CMTS and some number of CMs. The CMTS shall service all of the upstream and downstream channels; each CM can access one or more logical upstream chann... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.2 MAC Service Access Point | A MAC Service Access Point (MSAP) is an attachment to a MAC-sublayer domain (refer to clause 9.1.1). |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.3 Service Flows | The concept of Service Flows is central to the operation of the MAC protocol. Service Flows provide a mechanism for upstream and downstream Quality of Service management. In particular, Service Flows are integral to bandwidth allocation. A Service Flow ID defines a particular unidirectional mapping between a CM and the... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.4 Upstream Intervals, Minislots and 6,25 microsecond Increments | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.4.0 Upstream Transmission Timeline | The upstream transmission time-line is divided into intervals by the upstream bandwidth allocation mechanism. Each interval is an integral number of minislots. A "minislot" is the unit of granularity for upstream transmission opportunities. There is no implication that any PDU can actually be transmitted in a single mi... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.4.1 TDMA Mode | For DOCSIS 1.x channels, a minislot is a power-of-two multiple of 6,25 microsecond increments, limited to 2, 4, 8, 16, 32, 64, or 128 times 6,25 microseconds. For DOCSIS 2.0 and 3.0 TDMA, a minislot is a power-of-two multiple of 6,25 microsecond increments limited to 1, 2, 4, 8, 16, 32, 64, or 128 times 6,25 microsecon... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.4.2 S-CDMA Mode | For DOCSIS 2.0 and 3.0 S-CDMA channels, a minislot is not restricted to be a power-of-two multiple of 6,25 microsecond increments. Instead a minislot is a unit of capacity that is dependent on the modulation rate, number of spreading codes, and number of spreading intervals configured for the upstream channel. (This re... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.4.3 OFDMA Mode | For DOCSIS 3.1 channels, a minislot is not restricted to be a power-of-two multiple of 6,25 microsecond increments. Instead a minislot is a unit of capacity that is dependent on the number of subcarriers per minislot and the number of symbols in the OFDMA frame. The modulation rate on an OFDMA channel can vary from one... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.5 MAC Frame | A MAC Frame is a unit of data exchanged between two (or more) entities at the Data Link Layer. A MAC frame consists of a MAC Header (beginning with a Frame Control byte; see figure 6.2), and can incorporate a variable-length data PDU. The variable-length PDU includes 48-bit source and destination MAC addresses, data, a... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.6 Logical Upstream Channels | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.6.0 Logical Upstream Types | The MAC layer deals with logical upstreams. A logical upstream is identified with an upstream channel ID which is unique within the MSAP. A logical upstream consists of a contiguous stream of minislots which are described by UCD messages and allocated by MAP messages associated with a channel ID. A CM operating with Mu... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.6.1 Type 3 Logical Upstreams | Type 3 Logical Upstreams have operational parameters in their associated UCD messages that prevent the operation of DOCSIS 1.x CMs. See clause 6.4.3 for a detailed description of which parameter values make a channel a Type 3A or 3S Upstream. The UCD messages for Type 3 Logical Upstreams use a different MAC management ... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.6.2 Type 4 Logical Upstreams | Type 4 Logical Upstreams are identified by UCD Type 35 and can additionally have UCD Type 29. The presence of UCD Type 29 allows use of these logical upstream channels by DOCSIS 2.0 CMs. If the UCD Type 29 is not present, the channel is restricted to use by DOCSIS 3.0 CMs only. ETSI ETSI TS 103 311-3 V1.1.1 (2017-02) 8... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.2.6.3 Type 5 Logical Upstreams | Type 5 Logical Upstreams are identified by UCD Type 51 and contain parameters for OFDMA operation. This channel type is restricted for use by DOCSIS 3.1 and later CMs. |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.1.3 Future Use | A number of fields are defined as being "for future use" or Reserved in the various MAC frames described in the present document. These fields will not be interpreted or used in any manner by this version (3.1) of the MAC protocol. The CMTS shall transmit all Reserved or "for future use" fields as zero. The CM shall si... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2 MAC Frame Formats | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1 Generic MAC Frames | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.0 Generic MAC Frame Format | A MAC frame is the basic unit of transfer between MAC sublayers at the CMTS and the cable modem. The same basic structure is used in both the upstream and downstream directions. MAC frames are variable in length. The term "frame" is used in this context to indicate a unit of information that is passed between MAC subla... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.1 PMD Overhead | In the upstream direction, the PHY layer indicates the start of the MAC frame to the MAC sublayer. From the MAC sublayer's perspective, it only needs to know the total amount of overhead so it can account for it in the Bandwidth Allocation process. More information on this may be found in the PMD Sublayer clause of ETS... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.2 Ordering of Bits and Octets | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.2.1 Bit Ordering | For the SC-QAM upstream channel, within an octet, the least-significant bit is the first transmitted to the PHY. This follows the convention used by Ethernet and ISO/IEC 8802-3 [22]. This is often called bit-little-endian order. For both the SC-QAM and OFDM downstream channel and for the OFDMA upstream channel, the MPE... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.2.2 Octet Ordering | Within the MAC layer, when numeric quantities are represented by more than one octet (i.e. 16-bit and 32-bit values), the octet containing the most-significant bits is the first transmitted on the wire. This is sometimes called byte-big- endian order. |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.2.3 Textual Conventions | The present document uses the following textual conventions: • When tables describe bit fields within an octet, the most significant bits are topmost in the table. For example, in table 6.2, FC_TYPE occupies the two most-significant bits and EHDR_ON occupies the least-significant bit. • When figures depict bit position... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.2.4 Representing Negative Numbers | Signed integer values shall be transmitted and received by the CM and CMTS in two's complement format. |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.2.5 Type-Length-Value Fields | Many MAC messages incorporate Type-Length-Value (TLV) fields. Except for the cases of Primary Service Flow selection and MIC calculation among the TLVs encoded in a CM Configuration File, TLV fields are unordered lists of TLV-tuples. Some TLVs are nested (see Annex C). The CM or CMTS shall set all TLV Length fields, ex... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.3 MAC Header Format | The CM or CMTS shall use the MAC Header format as shown in figure 6.2. Figure 6.2: MAC Header Format NOTE 1: While figure 6.2 shows an extended header length of 0 - 24 bytes, the extended header length can range from 0 - 240 bytes in the MAC Header format compliant with pre-DOCSIS 3.1 specifications. The CM shall compl... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.1.4 Data PDU | The MAC Header may be followed by a Data PDU. The type and format of the Data PDU is defined in the Frame Control field of the MAC Header. The FC field explicitly defines a Packet Data PDU, an ATM Data PDU, an Isolation Packet Data PDU, and a MAC-Specific Frame. All CMs shall use the length in the MAC Header to skip ov... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.2 Packet-Based MAC Frames | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.2.1 Packet PDU and Isolation Packet PDU | The CM or CMTS MAC sublayer shall support both, a variable-length Ethernet/ISO/IEC 8802-3 [22]-type Packet Data PDU MAC Frame and a variable-length Ethernet/[22]-type Isolation Packet Data PDU MAC Frame. The Isolation Packet Data PDU MAC Frame is used to prevent certain downstream packets from being received and forwar... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.3 MAC Frames with FC_TYPE 0x01 | The FC_TYPE 0x01 is reserved for future definition. This PDU shall be silently discarded by CMs and CMTSs compliant with this version (DOCSIS 3.1) of the specification. DOCSIS-compliant version 3.1 CM and CMTS implementations shall use the length field to skip over MAC Frames with FC-TYPE 0x01. |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.4 MAC-Specific Headers | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.4.0 Overview | Several MAC Headers are used for very specific functions. These functions include support for downstream timing and upstream ranging/power adjustment, requesting bandwidth, fragmentation and concatenating multiple MAC frames. ETSI ETSI TS 103 311-3 V1.1.1 (2017-02) 88 Table 6.4 describes FC_PARM usage within the MAC Sp... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.4.1 Timing Header | A specific MAC Header is identified to help support the timing and adjustments required. In the downstream, this MAC Header shall be used by the CMTS on SC-QAM channels to transport the Global Timing Reference to which all cable modems synchronize. In the upstream, this MAC Header shall be used by the CM as part of the... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.4.2 MAC Management Header | A specific MAC Header is identified to help support the MAC management messages required. This MAC Header shall be used by CMs and CMTSs to transport all MAC management messages (refer to clause 6.4). The CM shall comply with figure 6.5 and table 6.6 for MAC Management Headers. The CMTS shall comply with figure 6.5 and... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.4.3 Request Frame | The Request Frame is the basic mechanism that the cable modem uses to request bandwidth. As such, it is only applicable in the upstream. Note that DOCSIS 3.1 CMs support Request Frames only when interoperating with DOCSIS 3.0 CMTSs, and only prior to registration. The CM shall not include any Data PDUs following the Re... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.4.4 Fragmentation Header | The use of fragmentation MAC Frames by DOCSIS 3.1 CMs is deprecated. The Fragmentation MAC Header provides the basic mechanism to split a larger MAC PDU into smaller pieces that are transmitted individually and then re-assembled at the CMTS. As such, Fragmentation is only applicable in the upstream. The CMTS shall comp... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.4.5 Queue-depth Based Request Frame | The Queue-depth Based Request Frame is the mechanism that a cable modem uses to request bandwidth in terms of bytes, not including or assuming any physical layer overhead FEC, physical layer padding. The Queue-depth Based Request Frame is only applicable in the upstream. The CM shall not include any Data PDUs following... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.4.6 Concatenation Header | A specific MAC Header is defined to allow multiple MAC frames to be concatenated by pre-DOCSIS 3.1 CMs. The concatenation header is not used by DOCSIS 3.1 CMs. A CMTS shall comply with figure 6.9 and table 6.10 for Concatenation MAC Headers. Figure 6.9: Concatenation MAC Header Format ETSI ETSI TS 103 311-3 V1.1.1 (201... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.5 Extended MAC Frame Length | Previous versions of DOCSIS specifications defined Packet PDU and MAC Management Message formats with length up to 1 522 bytes. DOCSIS 3.1 introduces support for extended packet sizes to comply with the requirements of IEEE 802.3as [20], which defines Ethernet frame formats up to 2 000 bytes. Similarly, the supported l... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6 Extended MAC Headers | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.0 Overview and General Requirements | Every MAC Header, except the Timing and Queue-depth Based Request Frame, has the capability of defining an Extended Header field (EHDR). The CM or CMTS shall indicate the presence of an EHDR field by the EHDR_ON flag in the FC field being set. Whenever this bit is set, then the CM or CMTS shall use the MAC_PARM field a... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.1 Piggyback Requests | Several Extended Headers can be used to request bandwidth for subsequent transmissions. These requests are generically referred to as "piggyback requests". They are extremely valuable for performance because they are not subject to contention as Request Frames generally are (refer to clause 7.2.2). Requests for additio... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.2 Request Extended Header | The Request Extended Header (EH_TYPE=1) is used to piggyback bandwidth requests on packets that do not have the Baseline Privacy extended headers. In that case, when operating with Multiple Transmit Channel Mode disabled, the CM shall use either the Request Extended Header with EH_LEN=3 or the BP_UP Extended Header to ... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.3 Fragmentation Extended Header | Pre-3.0 DOCSIS fragmented packets use a combination of the Fragmentation MAC header and a modified version of the Upstream Privacy Extended header. clause 6.2.6.4 describes the Fragmentation MAC header. The Upstream Privacy Extended Header with Fragmentation, also known as the Fragmentation Extended Header, transmitted... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.4 Service Flow Extended Header | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.4.0 Overview | The Service Flow EH Element is used to pass status information regarding Service Flow scheduling between the CM and CMTS. In previous version of the present document Service Flow EH Element was also used to signal information related to Payload Header Suppression. While PHS is deprecated in DOCSIS 3.1 the specification... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.4.1 Payload Header Suppression Header | Payload Header Suppression Header is deprecated in DOCSIS 3.1. |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.4.2 Unsolicited Grant Synchronization Header | The Unsolicited Grant Synchronization Header may be used to pass status information regarding Service Flow scheduling between the CM and CMTS. It is currently only defined for use in the upstream with Unsolicited Grant and Unsolicited Grant with Activity Detection scheduling services. (Refer to clause 7.2.3.3.) This ex... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.5 BP_UP2 Extended Header | The BP_UP2 EHDR is used when Baseline Privacy is enabled. When segment headers are enabled for a given service flow, the CM shall use the piggyback opportunity in the segment header for any piggyback requests for that service flow. If segment headers are not enabled for a service flow, the CM is not permitted to create... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.6 Downstream Service Extended Header | The Downstream Service Extended Header (DS EHDR) communicates to the CM information on how to process downstream packets. The DS EHDR contents vary depending on the EH_LEN, which may be one, three, or five bytes. The CMTS shall comply with table 6.17, table 6.18 and table 6.19 for DS EHDRs. This header is ignored by CM... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.7 DPV Extended Header | The CMTS MAY support the generation of the DPV Extended Header. The CMTS MAY place a DPV EHDR on any packet within any DSID or any Service Flow. The CMTS shall comply with table 6.20 for DPV EHDRs. A Modular CMTS Core MAY choose to place a DPV EHDR on any packet within any DEPI flow. This may be done in order to compar... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.2.6.8 Ordering of Extended Headers in Upstream DOCSIS | DOCSIS 3.1 imposes strict requirements on the order of transmission of extended header elements in MAC headers. The DOCSIS Security specification [14] already requires that the CM always makes the Baseline Privacy Extended Header element the first Extended Header in an upstream frame. While the presence of each extende... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.3 Segment Header Format | The CM shall use a Segment Header when transmitting packets in Multiple Transmit Channel Mode for service flows where use of the segment header is enabled. For these service flows, a Segment Header needs to appear at the beginning of any transmission made with IUCs 5, 6, 9, 10, or 11. Figure 6.11 shows the segment head... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.4 MAC Management Messages | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.4.1 MAC Management Message Header | CMs and CMTSs shall encapsulate MAC Management Messages in an LLC unnumbered information frame per ISO/IEC 8802-2 [21], which in turn is encapsulated within the cable network MAC framing, as shown in figure 6.12. Figure 6.12 shows the MAC Header and the MAC Management Message Header fields which are common across all M... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.4.2 Time Synchronization (SYNC) | Time Synchronization (SYNC) shall be transmitted by CMTS at a periodic interval to establish MAC sublayer timing. The CMTS shall format this message to use an FC field with FC_TYPE = MAC Specific Header and FC_PARM = Timing MAC Header, followed by a Packet PDU in the format shown in figure 6.13. The CMTS shall transmit... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.4.3 Upstream Channel Descriptor (UCD) | |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.4.3.0 UCD Message Format, Parameters and Attributes | An Upstream Channel Descriptor shall be transmitted by the CMTS at a periodic interval to define the characteristics of a logical upstream channel (see figure 6.14). A separate message shall be transmitted by the CMTS for each logical upstream that is currently available for use. The CMTS shall send UCD messages for a ... |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.4.3.1 Example of UCD Encoded TLV Data | An example of UCD encoded TLV data is given in figure 6.17. Figure 6.17: Example of UCD Encoded TLV Data ETSI ETSI TS 103 311-3 V1.1.1 (2017-02) 115 |
977e8a176c53922fd5283270c744fd61 | 103 311-3 | 6.4.3.2 Example of UCD Encoding of Channel Parameters for OFDMA Channels | Table 6.26: Example UCD Channel Encodings for an OFDMA Channel Type Length Value 28 (Subcarrier Spacing) 1 2 30 (Subcarrier Exclusion Band) 16 0 | 2 30 | 30 32 | 33 61 | 2047 31 (Unused Subcarrier Specification) 24 3 | 3 20 | 20 29 | 29 31 | 31 34 | 35 60 | 60 32 (Symbols in OFDMA frame) 1 12 As an example, table 6.26 ... |
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