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Re: [Xen-users] How to tell which tapX interface belongs to which domain

To: James Harper <james.harper@xxxxxxxxxxxxxxxx>
Subject: Re: [Xen-users] How to tell which tapX interface belongs to which domain...
From: Christian Horn <chorn@xxxxxxxxxxxx>
Date: Tue, 9 Oct 2007 07:30:51 +0200
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On Tue, Oct 09, 2007 at 12:00:29PM +1000, James Harper wrote:
> I noticed that when I do a 'brctl show', the tap interface is on the
> line before the vif interface, so I made use of that. Hopefully it's
> always true!

Also seen that, but how do you conclude from that to which domU the
tap-device belongs?

I think i found something usable:

- ping the ip of the domU on the tap-interface you want to identify,
i.e. 'ping -c2 ch_hvmadm'
I also have the mac of my domU on that interface from the xen-config,
its aa:00:00:00:00:03 in this case.

- from the ping we have the mac in the arp-cache, and 
'brctl showmacs xenadm0' shows the macs known on that bridge:
   port no mac addr             is local?  ageing timer
     2     00:03:d2:11:0d:fb    no            1.57
     4     6e:14:9d:77:3a:cd    yes            0.00
     4     aa:00:00:00:00:03    no          138.21
     1     fe:ff:ff:ff:ff:ff    yes            0.00

- the 'port' column of my well-known mac is important, its 4.
Issuing 'brctl show' i get the connected tap-interface on the
4th line:
   bridge name     bridge id       STP enabled     interfaces
   xenadm0         8000.6e149d773acd       no      vif0.0

So now for implementing it into my perl/rrdtool scripts..


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