Re: [Xen-users] a lot of packet loss

[Bhasker C V <bhasker@xxxxxxxxxxxxx>]

On Fri, 1 May 2009, Attila Szamos wrote:

> I've fix-ed the timesyncronization problem. But I don't know where to
> start with the network problem.
> If I ping the VM a lot of packet didn't get an echo reply.
>
> root@test6:~# ping perftest-vm2
> PING test-vm2 (172.27.68.28) 56(84) bytes of data.
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=1 ttl=64 time=0.346 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=2 ttl=64 time=0.048 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=3 ttl=64 time=0.039 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=4 ttl=64 time=0.041 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=6 ttl=64 time=0.032 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=7 ttl=64 time=0.044 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=8 ttl=64 time=0.038 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=43 ttl=64 time=8.05 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=56 ttl=64 time=0.042 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=57 ttl=64 time=0.036 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=58 ttl=64 time=0.041 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=59 ttl=64 time=0.038 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=60 ttl=64 time=0.041 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=61 ttl=64 time=0.038 ms
> 64 bytes from test-vm2 (172.27.68.28): icmp_seq=62 ttl=64 time=0.033 ms
>
> --- test-vm2 ping statistics ---
> 64 packets transmitted, 15 received, 76% packet loss, time 63064ms
> rtt min/avg/max/mdev = 0.032/0.594/8.056/1.995 ms
Does the ping directly to IP address too gives the same issue ?
sometimes DNS is a pain...
also on the domU side, try commenting out the complete resolv.conf
just to take DNS out of the way and try direct IP ping.

you can also on the domU side run a tcpdump and check why the particular
icmp sequence number is missing. you can see the replies from domU and
if the reply does not come to the dom0, then there could be a problem with
xen.
else
...

> I've tried to switch the networking to 'route' from 'bridge', but it
> didn't help. Any suggestions?
>
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Bhasker C V
Registered linux user #306349



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