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Re: [Xen-users] Strange network issue; Guest/DomU outgoing traffic



"Fischer, Anna" <anna.fischer@xxxxxx> writes:

> If you are tracing within DomU, assuming you are doing a simple Linux "ping 
> x.x.x.x" command where x.x.x.x is on the same network as your DomU, then the 
> only reason that you would not see an ICMP packet would be that you do not 
> have an ARP table entry for x.x.x.x on DomU. What does your ARP table show? 
> If there is no entry, then you should see an ARP packet in the trace. If you 
> do not see an ARP packet, then it could be that your routing is not set up 
> properly. What does ip route show?

ip route (well, I used netstat -rn)  showed the correct things.   my default
gateway was on the same network as the netmask of eth0, and netstat -rn showed
that.   the arp table had an unresolved entry for the default gateway and
nothing else.  deleting that entry and trying again would not incerement
the tx packet count even by 1.  

I even tried arping the default gateway.  the packet counters still would not
increment (and I didn't see any outgoing arp packets)   the syntax was right,
as I try it after reboot (rebooting the DomU not the Dom0)  and I see arp
packets as I would expect.   

when this is happening I ususally leave an inbound ping going from another 
host.  I see the packets heading in, nothing (not even an arp who-has) 
going out.  

> Do your interface counters / netstat values show any TX errors at all?

None.  

> >From your description I don't think this issue is Xen related.
> 
> When I had problems with libpcap, I actually saw interface packet counters 
> increasing, but no packets in libpcap. So this is a different issue.

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