Subject: Re: [vserver] Multiple visible IPs per guest
From: "John A. Sullivan III" <jsullivan@opensourcedevel.com>
Date: Thu, 21 May 2009 21:32:50 -0400

On Thu, 2009-05-21 at 13:40 -0700, 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.
> 
> 
> 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?
> 
> 2) If left out for the current IP are there any issues?
> 
> 
> \\||/
> Rod
Hi, Rod.  I usually prefer to use iproute and secondary addresses rather
than aliases.  It probably depends on whether or not some of your
applications and configurations are expecting aliases or not.

I never use the name parameter when configuring multiple IP addresses.
I may be wrong, but if I recall correctly, just adding an interface
definition does not create and bind the address.  I typically add the
new address in the host (ip add add x.x.x.x/y dev ethx) and then add it
to the host with naddress --add --nid <context id> --ip x.x.x.x

Someone please correct me if I am wrong.  Hope this helps - John
-- 
John A. Sullivan III
Open Source Development Corporation
+1 207-985-7880
jsullivan@opensourcedevel.com

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