[Planetlab-users] Capture multicast using libpcap

[Sebastian Meiling]

Hi all,

has anybody ever tried to capture multicast traffic on planetlab using 
tcpdump or other tools using libpcap?

As most PL sites provide at least two nodes, I tried to send IP 
multicast from one node to the other at the same PL site. While sending 
and receiving of multicast data works fine (as expected), I can only 
track outgoing multicast packets at sending node, but I am unable to see 
them with tcpdump at the receiver - but they reach the receiving 
program! For testing I used the ssmping tools, see here:

   http://www.venaas.no/multicast/ssmping/

I run 'ssmpingd' on Node A and 'ssmping <Node A>' on Node B. Node A is 
waiting for request from Node B and answers via multicast, which is 
received by Node B. As descibed above, I see outgoing multicast packets 
at Node A with tcpdump, but not at Node B, despite ssmping receiving 
multicast.

As far as I read in planetlab docu this issue has/might have something 
to do with VNET and/or VServer used by planetlab to isolate slices. Did 
anyone encounter this problem too and is there a workaround, to track 
multicast packets at the receiver anyway?

Regards,
   Sebastian

-- 
Sebastian Meiling
+---------------------------------------+
  Internet Technologies Research Group
  Department of Computer Science
  Hamburg University of Applied Sciences
  Berliner Tor 7, 20099 Hamburg, Germany
+---------------------------------------+
  Mail: sebastian.meiling at haw-hamburg.de
   Fon: +49 40 42875 - 8067
   Fax: +49 40 42875 - 8409
   Web: http://www.haw-hamburg.de/inet
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