[Xorp-users] malformed PIM REGISTER messages?

[Eckmann, Steve CTR MDA/IC]

I am tunneling multicast between a Cisco router and a Linux/XORP router, using PIM-SM. If the RP is on the XORP router everything works. If the RP is on the Cisco router then mcast receivers attached to the XORP router can receive traffic sent from hosts on the Cisco side of the tunnel, but mcast receivers on the Cisco side do not receive mcast traffic sent by hosts on the XORP side. Ethereal running on an intermediate router or on the Linux/XORP router reports that the (GRE-wrapped) PIM REGISTER messages sent by XORP are "Malformed", and no encapsulated UDP datagram appears in the Ethereal display. The Cisco router appears to immediately send a PIM REGISTER_STOP instead of sending a JOIN_PRUNE when it receives one of these PIM REGISTER messages. So it looks like there might be something wrong with the PIM REGISTER messages.
 
Any suggestions about what might cause this symptom? I'm running Fedora Core 4 Linux with XORP 1.2 (also tried the 1.3 Release Candidate; I see that official 1.3 became available yesterday...).
 
Thanks.
 
Steve