[88756] in North American Network Operators' Group
Re: Disaster recovery using as-prepend?
daemon@ATHENA.MIT.EDU (Ejay Hire)
Thu Feb 16 13:16:18 2006
From: "Ejay Hire" <ejay.hire@isdn.net>
To: Florian Weimer <fw@deneb.enyo.de>,
"Christopher J. Pilkington" <christopher.j.pilkington@gmail.com>
Cc: nanog@merit.edu
Date: Thu, 16 Feb 2006 12:00:34 -0600
In-Reply-To: <87r763nxv9.fsf@mid.deneb.enyo.de>
Errors-To: owner-nanog@merit.edu
Hello.
Answering the original question, as prepends are not a
definitive way to force all traffic to one site or the
other.
Two ways that definitely will work are.
1. Send a community to the upstream provider at the
backup site that causes them to set a lower plocalpref on
the route you send them vs. the route learned from the
internet.
2. If you have a large enough ip block, Advertise an
aggregate address from your backup site, and more
specifics from your primary. I.e. advertise a /23 from
your backup site and the same /23 as two /24's from the
primary.
-ejay
Thu, 16 Feb 2006 16:10:02 +0100
Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * Christopher J. Pilkington:
>
>> We have a disaster recovery site which will have a clone
>>of the myriad
>> production servers. We'd like to fail over to that site
>> automagically.
>>
>> I'm thinking advertising the same prefix and just doing
>>several
>> as-prepends. However, now I'm not sure if this is a
>>polite thing to
>> do or not.
>
> Can your backup servers run in parallel to your primary
>servers? How
> do you handle conflicting updates (assuming that the
>services are not
> completely stateless)?
