Re: [Xen-users] dom0 networking problem

[Jens Fiedler <jens.fiedler@xxxxxxxxxxxxxxxxxxx>]

John Smith wrote:

> > ARP response. The ARP response is then sent over the network (one single
> > switch),
> > passes the switch (checked using a hub after it), but does not show up
> > in the
> > Cheers,
> > -Jens
> Jens,
>
> it smells like a switch with autolearning.
> I would try it with a hub _in stead_ of the switch.
>
> Sincerely,
>
> Jan.
Hi,

The ARP response passes the switch, the hub was placed behind the switch 
in order to check
wheter the switch drops the ARP response. It does not, I can see the ARP 
responses using a
3rd machine (sniffer in the fig.) connected to that hub. So the switch 
is not the point of
failure.

   <---------------------ARP request----------------
   ----------------------ARP response---->
+-------+                                     +-------------+
|target |     +--------+       +-----+        | xen machine |
|machine|-----| switch |-------| hub |--------|peth0        |
+-------|     +--------+       +-----+        +-------------+
                                 |
                             +--------+
                             | sniffer|
                             +--------+

Additionally, when I look at the packet counters using 'ifconfig', the 
counters for TX and
RX go up, although tcpdump does not show any incoming ARP response on 
peth0. So the ARP
responses are received by the interface, but get dropped before coming 
to tcpdump or xenbr0.
peth0 counters for errors are 0. In tcpdump for peth0 I can see the 
outgoing ARP requests.
The only incoming packets I see are broadcasts from other machines 
(router adv, other
machines' ARP reqs for different IP addresses, not related to the xen box)

Still clueless,
   -Jens
                                        

--
Dipl.-Inform. Jens Fiedler
FhI FOKUS, Competence Center for NGNI
Tel.: +49 30 3463 7270
jens.fiedler@xxxxxxxxxxxxxxxxxxx

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