Configuring Ipv6 Multicast Routing And Forwarding - HP FlexNetwork 7500 Series Configuration Manual

Configuring IPv6 multicast routing and
forwarding
Overview
IPv6 multicast routing and forwarding uses the following tables:
•
IPv6 multicast protocols' routing tables, such as the IPv6 PIM routing table.
•
General IPv6 multicast routing table that summarizes the multicast routing information
generated by different IPv6 multicast routing protocols. The IPv6 multicast routing information
from IPv6 multicast sources to IPv6 multicast groups are stored in a set of (S, G) routing entries.
•
IPv6 multicast forwarding table that guides IPv6 multicast forwarding. The optimal routing
entries in the IPv6 multicast routing table are added to the IPv6 multicast forwarding table.
RPF check mechanism
An IPv6 multicast routing protocol relies on the existing IPv6 unicast routing information or IPv6
MBGP routes to create IPv6 multicast routing entries. When creating IPv6 multicast routing table
entries, the IPv6 multicast routing protocol uses the reverse path forwarding (RPF) check
mechanism to ensure IPv6 multicast data delivery along the correct path. The RPF check also helps
avoid data loops.
A multicast routing protocol uses the following tables to perform the RPF check:
•
IPv6 unicast routing table—Contains unicast routing information.
•
IPv6 MBGP routing table—Contains IPv6 MBGP multicast routing information.
RPF check process
The router performs the RPF check on an IPv6 multicast packet as follows:
The router chooses an optimal route back to the packet source separately from the IPv6 unicast
1.
and IPv6 MBGP routing tables.
In RPF check, the "packet source" means difference things in difference situations:
For a packet that travels along the SPT, the packet source is the IPv6 multicast source.
For a packet that travels along the RPT, the packet source is the RP.
For a bootstrap message originated from the BSR, the packet source is the BSR.
For more information about the concepts of SPT, RPT, source-side RPT, RP, and BSR, see
"Configuring IPv6
The router selects one of the optimal routes as the RPF route as follows:
2.
If the router uses the longest prefix match principle, the route with a higher prefix length
becomes the RPF route. If the routes have the same prefix length, the route with a higher
route preference becomes the RPF route. If the routes have the same route preference, the
IPv6 MBGP route becomes the RPF route.
For more information about the route preference, see Layer 3—IP Routing Configuration
Guide.
If the router does not use the longest prefix match principle, the route with a higher route
preference becomes the RPF route. If the routes have the same route preference, the IPv6
MBGP route becomes the RPF route.
In the RPF route, the outgoing interface is the RPF interface and the next hop is the RPF
neighbor.
PIM."
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