North American Network Operators Group

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Re: Disaster recovery using as-prepend?

  • From: Ejay Hire
  • Date: Thu Feb 16 13:18:07 2006


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 <[email protected]> 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)?