[Xorp-users] Multicast advice

[Pavlin Radoslavov]

> I have a linux PPP server with multiple clients connecting to it.
> I have a multicast application sending data on client A and I have
> a receiving multicast application on clients B and C.  The ppp
> server receives the multicast traffic from client A but doesnt
> forward it to client B or C.   Can anyone point me on the right
> direction on how to accomplish this?  I have tried xorp (pim-sm)
> on the PPP server but no luck.  ip_forward is on and rp_filter is
> off on all interfaces. When I ran xorp mc_forwarding was on all
> interfaces.
> 
> 
> A---->PPP SERVER<-----B
>        /\
>        |
>        C

A quick suggestion, because it is often a source of an error:
can you verify that the multicast packets originated by A have
TTL > 1.
If the TTL is not the problem, then make sure that:

1. Your PIM-SM router has the RP info. In your setup, the PPP SERVER
   probably should be the RP itself, so make sure that the
   "show pim rps" CLI command contains that info.
   The simplest way to do this is to use a static RP. Otherwise,
   if you use the Bootstrap mechanism, on startup you may have to
   wait on the order of 1-2 minutes until the BSR election happens
   and the Cand-RP set is distributed. Of course, in your setup you
   would have to configure the PPP Server as both a Cand-BSR and
   Cand-RP.

2. The PIM-SM router has the Join info from B and C. Use command
   "show pim join" to verify that. In particular, look for the "WC"
   entry for the (*,G) group, and for the "SG" entry for source A.

3. If the above info is correct, then make sure that "show pim mfc"
   shows the multicast-forwarding entry that PIM-SM has installed
   in the kernel. That entry should have iif = the interface toward
   A, and oifs set toward B and C.

4. Finally, if the "show pim mfc" output is correct, verify that the
   kernel itself contains that info. On Linux, the command is:
   cat /proc/net/ip_mr_cache

If the above info doesn't help, then please run XORP with all
traceoptions enabled, and send me your XORP configuration file and
the XORP log message. You don't have to CC the list, especially if
that information may be sensitive.

Regards,
Pavlin