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

[Luke S Crawford <lsc@xxxxxxxxx>]

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

> I guess you mean you do "arp -d x.x.x.x", and then "ping x.x.x.x", or "arping 
> x.x.x.x" where x.x.x.x is configured as your default gateway? That should 
> definitely cause an ARP request to go out. You do not have any weird 
> arpd/kernel configuration enabled?

Exactly.   

I'm not doing anything with arptables or otherwise changing the arp config
for this box (and it worked just fine for a period of months until one day
it just... didn't.)     this has happened on several DomUs, restarting the 
DomU fixes the problem.  

> Also, you do not have any weird network setup within your DomU? Like a 
> bridge, VLAN bonding, or IP forwarding, or IP aliases, or whatever else?

It just has one IPv4 address on eth0.  only one interface.  No iptables, even.
no bonding.  

> And, you only have a single interface assigned (and configured!) per virtual 
> machine? And you have /proc/sys/net/ipv4/conf/all/arp_filter set to 0?

I have not touched the arp_filter proc.  I checked on a box with the 
identical image and it is in fact zero.  but yes, one IP  and one eth
per virtual machene. 


> I guess you capture at the interface level with tcpdump, but for incoming 
> packets it could also be that they are not received on the higher level, e.g. 
> if you have packet filtering enabled or something similar. I guess you are 
> not running a firewall or something?

Nope, and from the domU, I see incoming packets in tcpdump just fine...
only outgoing that has the problem.  

no packet filtering.  

> > > Do your interface counters / netstat values show any TX errors at
> > all?
> > 
> > None.
> 
> Then this would be a failure somewhere in the IP stack, or possibly in the 
> ARP kernel code... If you are sure that you have not misconfigured anything, 
> then I would probably go for a kernel upgrade... 

Hm.  OK.   thanks.  I will try that.   

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