Re: Disaster recovery using as-prepend?

["Ejay Hire" <ejay.hire () isdn net>]

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)?