Re: [vserver] Multiple visible IPs per guest

From: Xavier Montagutelli <>
Date: Mon 25 May 2009 - 11:15:48 BST
Message-Id: <>

On Thursday 21 May 2009 22:40:25 Roderick A. Anderson wrote:
> I am moving a few Vserver hosts to a new IP range then to a new colo but
> not all at once. So I'm thinking I'd add the new IPs to the host and
> guests and make the necessary DNS entries. When the physical move time
> comes, down time will not include re-IPing. Once in place I'll take the
> old IPs out one at a time.
> _In theory_ this should work fine but I do have a couple of questions
> that came from some network work (fumbling) I was doing the other day.

We use multiple IP adresses for some VServers, so it works practically, not
only in theory ;-)

> On "The Great Flower Page" under the sub-section
> /etc/vservers/<vserver-name>/interfaces/<iface>
> name
> When this file exists, the interface will be named with the text in this
> file. Without such an entry, the IP will not be shown by ifconfig but by
> ip addr ls only. Such a labeled interface is known as an "alias" also
> (e.g. 'eth0:foo').
> 1) If I leave this out for the new IP are there any network issues I
> might run into?

I don't think so, the only drawback is outlined in your quote : the IP address
won't be shown by the "ifconfig" command used by 99% of the sysadmins, so it
may be confusing.

Another word : the name of the network interface is limited to 15 caracters,
including "eth0:". So be careful : if the name of the alias is too long, the
"vserver ... stop" won't remove the alias correctly.

> 2) If left out for the current IP are there any issues?

Sorry for my english, I'm not sure to understand the question.

The "name" can be any valid string. We use the context number as the alias,
because it is short and the network interface is already very long in our case
(we use VLANs => eth0.2002). We add "_2", "_3" for the additional interfaces.

If you use the IP address as the alias name, be careful with the 15 length !

> \\||/
> Rod

Xavier Montagutelli                      Tel : +33 (0)5 55 45 77 20
Service Commun Informatique              Fax : +33 (0)5 55 45 75 95
Universite de Limoges
123, avenue Albert Thomas
87060 Limoges cedex
Received on Mon May 25 11:17:46 2009
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