[Xorp-users] Cand-RP is ignored

[Pavlin Radoslavov]

> I had to restart Xorp after several months, because another university
> decided to announce 224.0.0.0/4 as RP (which is bad, because the
> "network guys" for the whole network already do that (not the whole
> network though)) which (sort of) crashed my Xorp. Ironically other Xorp's
> in this university network had no problems and still have no problems.

What XORP version did you run at that time, and do you have any
additional info about the crash (coredump image for the backtrace,
log messages, etc).

> However, this issue is solved and a new problem arose. I need to start a
> local RP for the group used for local streams (which should go out into the
> university), but the Cand-RP mechanism seems to not work at all. I did
> not update anything in between the restart of Xorp and the time it was
> still running fine. After I noticed that something was wrong I updated
> Xorp to latest CVS and installed a recent kernel.
> 
> Even with TRACE options I do not see anything that indicates a working
> (Cand-)RP. Furthermore I do not see any packet indicating something in
> this direction.
> 
> Other users with the same setup can start RPs without a problem. I tried
> setting up a RP for "my" group and indeed the packets are sent to the
> host running Xorp with that RP (but are answered with "Stop" messages,
> confusing).

In general, all PIM-SM routers in the middle (at least, between the
receivers and the RP, and the sender's DR) must have consistent
Cand-RP information. Hence, if you have configured your own Cand-RP,
make sure that all affected routers have that information. If you
used a static RP configuration, then obviously the other routers
also need to be configured with that static RP info.

If you configured a Cand-RP using the Bootstrap mechanism, make sure
that this information is propagated properly to the rest of the
routers.

In xorpsh, the following commands can be useful to make sure the
Cand-RP information is consistent:

show pim rps
show pim bootstrap
show pim bootstrap rps

Futhermore, if you have your "own" multicast group with its own
Cand-RP, then make sure that its rp-priority has higher priority
than the other Cand-RPs for overlapping multicast prefixes such as
224.0.0.0/4.
Note that smaller value for rp-priority means higher priority,
while in case of bsr-priority and dr-priority is just the opposite.

Hope that helps,
Pavlin