IPv6 Multicast Changeless Routes
Just as in IPv4, multicast acquisition fundamentally builds its acquisition table based on the unicast
routing table. Before any multicast cartage can be routed, that cartage charge canyon the router’s RPF
check. That is, it charge accept accustomed on the interface that the router’s unicast acquisition table indicates
is the actual aisle aback against the cartage source.
For tunnels, in particular, the RPF analysis can account problems. If multicast cartage arrives over a
tunnel instead of the concrete interface over which the unicast acquisition table indicates that traffic
should accept arrived, again the router will abandon that traffic. To anticipate this behavior, you can
configure changeless multicast routes to acquaint the router as to which interface the cartage should arrive
on. This will acquiesce the RPF analysis to pass. In IPv6, unicast and multicast changeless routes use the same
command, ipv6 route, but with altered options.
For example, if you apprehend all multicast cartage on a router to access over the tunnel0 interface,
configure the changeless multicast avenue as follows:
StewPerry (config)# ipv6 avenue ::/0 adit 0 multicast