[pim] anycast-rp with pim (rfc4610) when an RP reboots

[Pekka Savola <pekkas at netcore.fi>]

Hello,

My colleague started thinking on this and it seems there is a caveat 
in the use of PIM for anycast-rp compared to MSDP.

Assume a stable state of 10 sources with two RPs in an anycast-RP set. 
Both RPs have information about all sources.  All sources are closer 
to RP_1.  All receivers are attached to RP_2.

Now, RP_2 reboots.  RP_1 does not know that the router has rebooted. 
In consequence, it does not re-register sources to RP_2 until DRs 
restart registering.  In consequence, the receivers attached to RP_2 
do not get the transmissions after routing reconverges to RP_2.

Did I get this right?  Are there any mitigations for this?  PIM-PORT 
could offer a way to fix this, obviously, but it may a bit far off 
yet.

--
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings