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



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

> You are tracing this within the guest OS? Or are you tracing on the bridge 
> within Dom0?


Assuming the original poster has the same problem I do, within the DomU.

only one guest has a problem at a time, and the problem remains even if i
'xm save' and then 'xm restore' the guest.

> Again, you are tracing this within the guest OS? What do the stats on the 
> guest network interface say? Do you see packet counters increasing (both 
> within the guest OS eth0, and on vifX.0 in Dom0?) when you are sending 
> packet? 

after you reset the interfaces within the guest, the transmitted packet
count stays at 1.  

> If you only have a single guest failing on Xen, then I would guess this is an 
> issue with the guest OS and not with anything relating to Xen networking. 
> What kernel does the guest OS run?


In my case, CentOS 5.1 kernel-xen   (I don't remember exact uname.  
sorry, I know that is important.)  


> > Does anyone have an idea about the cause or a solution to this problem?
> 
> I have seen strange things with libpcap under certain guest OS versions when 
> used with Xen's netfront driver... libpcap is used for tcpdump and some 
> network testing tools (potentially the ones you are using). It might be worth 
> trying to also trace packets on the backend devices in Dom0, and also have a 
> look at packet counters on all interfaces (Dom0/DomU).


the packet counters within the DomU, in my case, would increment for rx, 
for tx, they would not increment.   this looked the same if you looked at
the iface from within the domu or within the dom0  (which makes sense, if the
DomU doesn't think it's transmitting, the dom0 is unlikely to see a packet)  

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