There are two types of interfaces applicable to IGMP on a CM complying with 3.0 and later versions of DOCSIS specifications when it is registered with Multicast DSID Forwarding disabled or with a Pre-3.0 DOCSIS CMTS. These are the HFC-Side and CMCI-Side interfaces, respectively. Application of the IGMP-STD-MIB to a CM complying with 3.0 and later versions of DOCSIS specifications is presented in terms of passive and active CM operation and these two interface types. The CM MUST implement the passive IGMP mode. Additionally, the CM MAY implement the active IGMP mode. If the CM implements the active IGMP mode, the CM MUST support a capability to switch between modes.
B.2.1 IGMP Interface Table Objects
The following table defines the objects that are expected to be supported in the CM when operating in Active or Passive Proxy modes. Any deviation or clarification of the expected values from [RFC 2933] is noted in the sections following the table. If the requirements for a given MIB object denote per [RFC 2933], the expected values for the objects do not deviate from the expectations defined in the RFC.
Table B–1 - IGMP-STD-MIB igmpInterfaceTable Objects
MIB OBJECT CM PASSIVE CM ACTIVE
HFC CMCI HFC CMCI
igmpInterfaceIfIndex "2" "1" "2" "1" igmpInterfaceQueryInterval R/O Always "0" Per [RFC 2933] R/O
Always "0"
Per [RFC 2933] igmpInterfaceStatus Per [RFC 2933] Per [RFC 2933] Per [RFC 2933] Per [RFC 2933] igmpInterfaceVersion "2" "2" "2" "2" igmpInterfaceQuerier Per [RFC 2933] Per [RFC 2933] Per [RFC 2933] Per [RFC 2933] igmpInterfaceQueryMaxResponseTime R/O Always "0" R/O R/O Always "0" Per [RFC 2933] igmpInterfaceQuerierUpTime Per [RFC 2933] "0" Per [RFC 2933] Per [RFC 2933] igmpInterfaceQuerierExpiryTime "0" "0" "0" "0" igmpInterfaceVersion1QuerierTimer "0" "0" Per [RFC 2933] Per [RFC 2933] igmpInterfaceWrongVersionQueries Per [RFC 2933] Per [RFC 2933] Per [RFC 2933] Per [RFC 2933] igmpInterfaceJoins "0" Per [RFC 2933] "0" Per [RFC 2933] igmpInterfaceProxyIfIndex "0" "2" "0" "2"
MIB OBJECT CM PASSIVE CM ACTIVE
HFC CMCI HFC CMCI
igmpInterfaceGroups "0" Per [RFC 2933] "0" Per [RFC 2933] igmpInterfaceRobustness "0" "0" Per [RFC 2933] Per [RFC 2933] igmpInterfaceLastMemberQueryIntvl R/O Always "0" R/O
See details below
R/O Always "0" 0-255 ms, default 100 ms.
B.2.1.1 igmpInterfaceQueryInterval
B.2.1.1.1 Passive Mode
CMCI-side: The value of igmpInterfaceQueryInterval of a CM in Passive Mode is the interval between queries received from an upstream Querier.
B.2.1.1.2 Active Mode
CMCI-side: The Query Interval is the interval between General Queries sent by the CMCI Querier. Default: 125 seconds
B.2.1.2 igmpInterfaceQuerier
B.2.1.2.1 Passive Mode
HFC-side: The HFC side's igmpInterfaceQuerier of a CM in Passive Mode is the address of an upstream IGMP Querier device.
CMCI-side: The CMCI side's igmpInterfaceQuerier of a CM in Passive Mode is the address of an upstream IGMP Querier device.
B.2.1.2.2 Active Mode
HFC-side: The HFC side's igmpInterfaceQuerier of a CM in Active Mode is the address of an upstream IGMP Querier.
CMCI-side: Active CMs report the CMCI Interface. However, active CMs that participate in IGMP Querier negotiation on the CMCI may report a different CPE.
B.2.1.3 igmpInterfaceQueryMaxResponseTime
B.2.1.3.1 Passive Mode
CMCI-side: This value is derived from observation of maximum query response time advertised in IGMPv2 queries received from an upstream querier.
B.2.1.3.2 Active Mode
CMCI-side: The maximum query response time advertised in IGMPv2 queries on this interface.
B.2.1.4 igmpInterfaceQuerierExpiryTime
B.2.1.4.1 Passive Mode
CMCI-side: In Passive Proxy mode, the CM will return a 0 for this object.
B.2.1.4.2 Active Mode
CMCI-side: In Active mode, the CM is an active querier for the CMCI attached networks. As such, the value of this object is 0.
B.2.1.5 igmpInterfaceJoins
B.2.1.5.1 All Modes
CMCI-side: The CM counts all unsolicited membership reports for the CMCI interface only.
B.2.1.6 igmpInterfaceGroups
B.2.1.6.1 All Modes
CMCI-side: This counter contains the number of entries in the Cache table for this interface.
B.2.1.7 igmpInterfaceLastMembQueryIntvl
B.2.1.7.1 Passive Mode
CMCI-side: This read-only value is derived from Group-Specific Queries sent in response to Leave Group messages received from an upstream querier.
B.2.1.7.2 Active Mode
CMCI-side: The Last Member Query Interval is the Max Response Time inserted into Group-Specific Queries sent in response to Leave Group messages, and is also the amount of time between Group-Specific Query messages. This value may be tuned to modify the "leave latency" of the network. A reduced value results in reduced time to detect the loss of the last member of a group. Valid entries for this object range between 0 and 255 ms with a default value of 100.
B.2.2 igmpCacheTable
The following table defines the objects that are expected to be supported in the CM when operating in Active or Passive Proxy modes. Any deviation or clarification of the expected values from [RFC 2933] is noted in the sections following the table. If the requirements for a given MIB object denote Per [RFC 2933], the expected values for the objects do not deviate from the expectations defined in the RFC.
Table B–2 - IGMP-STD-MIB igmpCacheTable Objects
MIB OBJECT CM PASSIVE CM ACTIVE
HFC CMCI HFC CMCI
igmpCacheAddress N/A Per [RFC 2933] N/A Per [RFC 2933] igmpCacheIfIndex N/A "1" N/A "1"
igmpCacheSelf N/A R/O Always FALSE N/A See Below igmpCacheLastReporter N/A Per [RFC 2933] N/A Per [RFC 2933] igmpCacheUpTime N/A Per [RFC 2933] N/A Per [RFC 2933] igmpCacheExpiryTime N/A Per [RFC 2933] N/A Per [RFC 2933] igmpCacheStatus N/A Per [RFC 2933] N/A Per [RFC 2933] igmpCacheVersion1HostTimer N/A "0" N/A Per [RFC 2933]
B.2.2.1 igmpCacheAddress
B.2.2.1.1 All Modes
B.2.2.2 igmpCacheSelf
B.2.2.2.1 Passive Mode
CMCI-side: The CM's igmpCacheSelf is always set to false in passive mode.
B.2.2.2.2 Active Mode
CMCI-side: Implementation specific. If the CM is configured to be a member of the group, then membership reports are sent with the IP Address of the CM but only be sent in proxy for active sessions on the CMCI (e.g., the CM should not be a member of a multicast group that is not active on the CMCI). If the CM is not configured to be a member, then the source IP Address of membership reports should be set to the current value of the
Annex C Protocol Filtering (Normative)
DOCSIS 3.1 supports two IP protocol filtering methods consisting of the legacy IP filtering mechanism specified in [RFC 4639] and Upstream Drop Classifiers (UDCs) which are an outgrowth of the QoS classification mechanism. IP filtering continues to operate in DOCSIS 3.1 as it has in previous versions of the specification, though the minimum number of filtering rules has been increased from sixteen (16) to sixty-four (64). IP filters are limited to support of IPv4 protocols, while UDCs can be used for IPv4, IPv6, and LLC in a common framework with QoS classification. UDCs and IP filters are mutually exclusive modes and only one filtering method is permitted to operate at a time.
UDCs are modeled on the existing QoS Classifiers that were introduced in DOCSIS 1.1. UDCs apply only to the CM, the RF interface and only in the upstream direction of flow. The use of UDCs facilitates delegation of upstream protocol filtering at the CM through parameters in the configuration file that can be controlled by the CMTS. Any packet classified by the Upstream Drop Classifier rule is discarded, conceptually similarly to directing an IP route to "null 0" or output to /dev/null in a UNIX system.
As with IP filters, UDC rules may be configured through the CM configuration file statically, assigned dynamically from the CMTS through a Group ID reference in the CM configuration file, dynamically added, changed or deleted after registration through a DSC (Dynamic Service Change) MAC management message from the CMTS, or both the static and dynamic configuration methods may be used together. The CMTS alone provides the downstream protocol filtering and can further reinforce the upstream classification policy through Subscriber Management traffic filtering functionality.
Among the specific requirements for classification at the CM, the CM is required to perform protocol filtering from the host CPE(s) to the RF interface when UDCs are enabled, or protocol filtering from any interface to or from the RF interface when IP filtering is enabled. All ICMP (ICMPv4 and ICMPv6) and IP packets will be forwarded from the CMCI interface to the RFI upstream interface based on rules outlined in the Upstream Drop Classifiers section of [MULPIv3.1], unless they are specifically required to be discarded according to applied protocol filtering or classification rules.
It is recommended that to avoid unexpected behavior, consumption of excess local resources and oversized
configuration files, the configuration of Upstream Drop Classifiers not be configured simultaneously with the legacy IP filters. It should also be noted that when a DOCSIS 3.1 CM registers with a DOCSIS 3.1 CMTS when UDCs are enabled, only the UDC parameters will be utilized by the CM. When a DOCSIS 3.1 CM registers with a Pre-3.0 DOCSIS CMTS, or a Pre-3.0 DOCSIS CM is registered with a DOCSIS 3.1 CMTS, only the IP filters configured in the CM configuration file are used.