[Xen-users] Mutlicast corruption using FC6

[Erwan Velu <erwan@xxxxxxxxxxxx>]

Hello all,

In my DomU, I've been experiencing some network corruption using some
UDP multicast packets.
Take two DomU on two different hosts and generates some multicast
traffic using mgen (http://cs.itd.nrl.navy.mil/work/mgen/index.php)
This tool is able to check integrity using the "check" option. I've been
running that tool for hours without any errors.

Then, just generate some unicast traffic between the same hosts using
netpipe (http://www.scl.ameslab.gov/netpipe/).
Once netpipe generates some packets bigger than 256K, mgen reports some
corruption.

I've been doing more tests, here come the results:
- if the two domU are on the same host this bug doesn't occur
- if I use mgen to generates some unicast UDP packets between the two
domU instead of multicast, this problem doesn't occur
- if I do the same scenario using some dom0 instead of the domU, this
problem doesn't occur

I would like to know if some experienced that and have any idea on how
it could be fixed in Xen or if I am doing something wrong ?

-------------------------
Configuration:
DomU: FC6, 2.6.20-1.2952.fc6xen
   kernel-xen-2.6.20-1.2952.fc6
   xen-3.0.3-8.fc6
   kernel-xen-devel-2.6.20-1.2952.fc6
   xen-libs-3.0.3-8.fc6
   kernel-xen-devel-2.6.20-1.2952.fc6

Dom0: FC6, 2.6.20-1.2952.fc6xen
   kernel-xen-2.6.20-1.2952.fc6
   xen-3.0.3-8.fc6
   kernel-xen-devel-2.6.20-1.2952.fc6
   xen-libs-3.0.3-8.fc6
   net driver: tg3

Hardware: x86_64 hosts with 1G of ram
Each domU have 256M of ram

NPtcp (netpipe client) used to this test is available at :
https://84.14.1.77/xenmcast/NPtcp

mgen used for this test is available at : https://84.14.1.77/xenmcast/mgen

Command used on the first domU to generate the mcast traffic for 30mn:
./mgen check event "0.0 ON 0 UDP SRC 30788 TXBUFFER 2000 DST
228.168.0.17/30788 POISSON [100 300] INTERFACE eth0" check event "1800.0
OFF 0"

Command used on the other domU to receive the mcast traffic for 30mn:
./mgen check event "LISTEN UDP 30788" event "0.0 JOIN 228.168.0.17 PORT
30788 INTERFACE eth0" event "1800.0 LEAVE 228.168.0.17" log "test.log"
mgen will show on the console if some checksum error occurs

Command used to receive the netpipe traffic on the second domU:
./NPtcp

Command used to generate the netpipe traffic of the first domU:
./NPtcp -h <host_ip_of_the_other_domU>



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