Re: [Xen-users] Cisco switch issue -- after Debian updates had me stumped...

[Zary Matej <matej.zary@xxxxxxxxx>]

>From: xen-users-bounces@xxxxxxxxxxxxx [xen-users-bounces@xxxxxxxxxxxxx] On 
>Behalf Of Andrew McGlashan [andrew.mcglashan@xxxxxxxxxxxxxxxxxxxxx]
>Sent: 11 August 2012 20:10
>To: xen-users@xxxxxxxxxxxxxxxxxxx
>Subject: [Xen-users] Cisco switch issue -- after Debian updates had me  
>stumped...
>
>Hi,
>
>I just wanted to report that I did some updates on my Debian VM
>(web/mail/dns server) which runs under Xen, also a Debian server and
>which I also installed updates.
>
>When I rebooted the Xen server I couldn't get to my VM from any machine
>on my network other than the Xen server itself.  So networking on the
>physical machine was fine.
>
>Both ssh and ping failed from every machine on my network that I tried,
>except from the Xen server which worked fine; the Xen server could be
>pinged without issue and connected to via ssh from any machine on my
>network.
>
>I immediately thought the problem was related to the updates (either the
>VM or Xen server) that I just installed.  However, I couldn't find
>anything that looked out of place and I was thinking about rolling back
>changes.
>
>Then I decided to pull the plug on my Cisco switch and reboot it.
>Everything come back to normal after the switch had finished rebooting.
>
>Hopefully my little story might help someone else.
>
>Cheers
>
>--
>Kind Regards
>AndrewM
>
>Andrew McGlashan
>Broadband Solutions now including VoIP

Hi there, sounds like you might have port security enabled on your Cisco switch 
(eg 
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/port_sec.html).
  If you don't have MAC address in your VM config, the VM nic gets "random" MAC 
after restart (IIRC) and if you have port security on cisco switchport enabled, 
the new MAC address can errdisable that port of just don't allow the new MAC 
address depending on the switch config. Might be worth checking out whether 
this was the casue. :)

regards

Matej
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