SG-based IPv6 multicast forwarding

When PIM snooping for IPv6 is configured, SG-based forwarding can be enabled, which causes the IPv6 multicast forwarding to be based on both the source (if specified) and destination IPv6 address in the received join.

Enabling SG-based forwarding increases the MFIB usage if the source IPv6 address or higher 96 bits of the destination IPv6 address varies in the received joins compared to using MAC-based forwarding.

The following output shows a service with PIM snooping for IPv6 that has received joins for two multicast groups from different sources. As the forwarding mode is SG-based, there are two MFIB entries, one for each of the two groups.

*A:PE# show service id 1 pim-snooping group ipv6
===============================================================================
PIM Snooping Groups ipv6
===============================================================================
Group Address           Source Address          Type     Incoming          Num
                                                         Intf              Oifs
-------------------------------------------------------------------------------
ff0e:db8:1000::1        2001:db8:1000::1        (S,G)    SAP:1/1/1         2
ff0e:db8:1001::1        2001:db8:1001::1        (S,G)    SAP:1/1/1         2
-------------------------------------------------------------------------------
Groups : 2
===============================================================================
*A:PE#

*A:PE# show service id 1 all | match "Mcast IPv6 scope"
Mcast IPv6 scope  : sg-based
*A:PE#

*A:PE# show service id 1 mfib
===============================================================================
Multicast FIB, Service 1
===============================================================================
Source Address  Group Address         Port Id                      Svc Id   Fwd
                                                                            Blk
-------------------------------------------------------------------------------
2001:db8:1000:* ff0e:db8:1000::1      sap:1/1/1                    Local    Fwd
                                      sap:1/1/2                    Local    Fwd
2001:db8:1001:* ff0e:db8:1001::1      sap:1/1/1                    Local    Fwd
                                      sap:1/1/2                    Local    Fwd
-------------------------------------------------------------------------------
Number of entries: 2
===============================================================================
*A:PE#

SG-based IPv6 multicast forwarding is supported when both plain PIM snooping and PIM proxy are supported.

SG-based forwarding is only supported on FP3- or higher-based line cards. It is supported in all services in which PIM snooping for IPv6 is supported, with the same restrictions.

It is not supported in the following services:

In any specific service, SG-based forwarding and MLD snooping are mutually exclusive. Consequently, MLD snooping uses MAC-based forwarding.

It is not supported in services with:

It is not supported on connected SR OS routers configured with improved-assert.

It is not supported with the following forms of default SAP: