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:
PBB B-VPLS
PBB I-VPLS
Routed-VPLS (including with I-VPLS and BGP-EVPN)
BGP-EVPN-MPLS (including PBB-EVPN)
VPLS E-Tree
Management VPLS
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:
subscriber management
multicast VLAN Registration
video interface
It is not supported on connected SR OS routers configured with improved-assert.
It is not supported with the following forms of default SAP:
*
*.null
*.*