[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...).
>
>Unfortunately, I don't have access to a Cisco router to try to
>replicate your setup.
>Can you run tcpdump instead and test whether you see similar
>"malformed" message. If "yes", could you send me the content of that
>malformed packet.
>Also, what is the Linux distribution and kernel version you are
>using?

Fedora Core 4 with 2.6.11-1.1369_FC4 kernel.
We got the same result without tunneling: we connected the Linux/XORP router directly to the Cisco router and still see the Cisco router responding with REGISTER_STOP to Linux REGISTER messages (that Ethereal considers malformed). I don't know how to tell whether tcpdump considers a packet malformed; it didn't complain about the REGISTER message in the attached file. Maybe somebody here is willing and able to do a sanity check on it; I depend on Ethereal for that...

Thanks.

Steve
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