Usage notes

This section describes the usage of sub-id and brg-id criteria.

Long sub-ids and long brg-ids are automatically enabled without having to explicitly enable them by provisioning additional CLI commands.
Although, the internal ANCP strings are 64 characters long, some of the external ANCP strings are limited to 63 characters. This is the limitation of the ANCP protocol and some of these strings are:
- Access-Loop-Circuit-ID TLV
- Access-Loop-Remote-ID TLV
- Access-Aggregation-Circuit-ID-ASCII
Consequently, the maximum size of externally controlled ANCP parameters remains at 63 characters (such as the ANCP protocol, RADIUS, CLI). This means that when ANCP is used, the operators should restrict the sub-id string to a maximum of 63 characters, or always provide and explicit ANCP string that is a maximum of 63 characters in length.
Multicast host-tracking is not supported with long sub-ids. This means that the hosts with a sub-id longer than 32 characters are excluded from host tracking. The sub-id key length for host-tracking related MIB tables remain unchanged at 32 characters and only contains subs with short sub-ids.

The following MIBs are not supported for long sub-ids:
- tmnxSubGrpTrkEntry
- tmnxSubHostGrpTrkEntry
- tmnxSubHostSapTrkEntry
- tmnxSubHostTrkEntry
- tmnxSubHostTrkStatsEntry
- tmnxSubTrkPlcySubscriberEntry
- tmnxSubTrkStatusEntry
Multicast host tracking only works with short sub-ids and is configured as follows:
```
configure
  subscriber-management
      host-tracking-policy <policy-name>
            egress-rate-modify [agg-rate-limit | scheduler <sch-name>]
 
configure
  subscriber-management
      sub-profile <subscriber-profile-name>
          host-tracking-policy <policy-name>  => mutually exclusive with igmp-policy
```
However, multicast HQoS adjustment is supported with long sub-ids, and should be deployed as a replacement for legacy multicast host tracking. Multicast HQoS adjustment is configured as follows:
```
configure
  subscriber-management
      igmp-policy <policy-name>
              egress-rate-modify [egress-aggregate-rate-limit | scheduler <name>]
 
configure
  subscriber-management
      sub-profile <subscriber-profile-name>
              igmp-policy <policy-name>
```
With the introduction of the long sub-id and long brg-id options, the show command output is rearranged by inserting additional line breaks and by wrapping the long sub-id and long brg-id at the end of the line. For example, the sub-id subidlong.123456789_123456789_123456789 123456789_123456789_3333 is wrapped as follows:

===============================================================================
Subscriber                             : subidlong.123456789_123456789_12345678
                                         9 123456789_123456789_3333
===============================================================================

In a multi-homing environment, the internal short sub-ids and short brg-ids are not synchronized. This means that they are independently derived on each node, meaning that if they are needed by the operator, they have to be retrieved by the management system after every switchover.

In most cases, the operator is not aware of the internal sub-id and brg-id. Their awareness is required only if an SNMP table walk is performed in one of the 11 MIB tables where the long sub-id and long brg-id causes the key to exceed the 128 character limit. If an entry with an internal sub-id or brg-id in one of the tables is found, then these internal values can be used to find the real (long) subscriber identity with a help of the conversion tables (tmnxSubShortEntry and tmnxSubBrgShortEntry).
Internally generated sub-ids and brg-ids are not saved in a persistency file. The sub-ids and brg-ids change after a reboot. Similar to multi-homing, if they are needed by the operator, they must be re-retrieved after a chassis reboot even when persistency is enabled.