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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Implementing IPv6 Multicast
Implementing IPv6 Multicast
Multiprotocol BGP for the IPv6 Multicast Address Family
The multiprotocol BGP for the IPv6 multicast address family feature provides multicast BGP extensions
for IPv6 and supports the same features and functionality as IPv4 BGP. IPv6 enhancements to multicast
BGP include support for an IPv6 multicast address family and network layer reachability information
(NLRI) and next hop (the next switch in the path to the destination) attributes that use IPv6 addresses.
Multicast BGP is an enhanced BGP that allows the deployment of interdomain IPv6 multicast.
Multiprotocol BGP carries routing information for multiple network layer protocol address families; for
example, IPv6 address family and for IPv6 multicast routes. The IPv6 multicast address family contains
routes used for RPF lookup by the IPv6 PIM protocol, and multicast BGP IPV6 provides for interdomain
transport of the same. Users must use multiprotocol BGP for IPv6 multicast when using IPv6 multicast
with BGP because the unicast BGP learned routes will not be used for IPv6 multicast.
Multicast BGP functionality is provided through a separate address family context. A subsequent
address family identifier (SAFI) provides information about the type of the network layer reachability
information that is carried in the attribute. Multiprotocol BGP unicast uses SAFI 1 messages, and
multiprotocol BGP multicast uses SAFI 2 messages. SAFI 1 messages indicate that the routes are only
usable for IP unicast, but not IP multicast. Because of this functionality, BGP routes in the IPv6 unicast
RIB must be ignored in the IPv6 multicast RPF lookup.
A separate BGP routing table is maintained to configure incongruent policies and topologies (for
example, IPv6 unicast and multicast) by using IPv6 multicast RPF lookup. Multicast RPF lookup is very
similar to the IP unicast route lookup.
No MRIB is associated with the IPv6 multicast BGP table. However, IPv6 multicast BGP operates on
the unicast IPv6 RIB when needed. Multicast BGP does not insert or update routes into the IPv6 unicast
RIB.
NSF and SSO Support In IPv6 Multicast
Support for nonstop forwarding (NSF) and stateful switchover (SSO) is provided in IPv6 Multicast.
Bandwidth-Based CAC for IPv6 Multicast
The bandwidth-based call admission control (CAC) for IPv6 multicast feature implements a way to
count per-interface mroute state limiters using cost multipliers. This feature can be used to provide
bandwidth-based CAC on a per-interface basis in network environments where the multicast flows use
different amounts of bandwidth.
This feature limits and accounts for IPv6 multicast state in detail. When this feature is configured,
interfaces can be limited to the number of times they may be used as incoming or outgoing interfaces in
the IPv6 multicast PIM topology.
With this feature, switch administrators can configure global limit cost commands for state matching
access lists and specify which cost multiplier to use when accounting such state against the interface
limits. This feature provides the required flexibility to implement bandwidth-based local CAC policy by
tuning appropriate cost multipliers for different bandwidth requirements.
Implementing IPv6 Multicast
• Enabling IPv6 Multicast Routing, page 1-13
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