I have 2 RPs in my scenario. I want RP1 to only entertain FF08::9, whereas RP2 shall be the rp for rest of the range i.e. FF00:/8. When i define the access-list with /128 prefix and try to apply it when configuring rp on RP1, it gives an error that 128 mask cant be applied. Can someone tell me in ipv6 if i want RP for just single prefix, what do i need to do ?
This is a known IOS limitation. To be honest, I do not know if there is any sensible explanation for this - it is just implemented this way. If it is allowed to use the "deny" clauses in the ACL you can perhaps solve your problem by using a /127 multicast group prefix and denying the unwished multicast group address. Otherwise, I believe it is not possible to define an IPv6 RP for a single multicast group in Cisco IOS.