BGP Anywhere - Global Redundancy

Thu Apr 7 00:35:35 UTC 2005

All,
We're an ASP and are considering adding a secondary Backup Datacenter
(BDC) in the US to protect our web presence. 

My goal is to ensure automatic failover of my Primary DC's (IP) traffic
to the BDC in the event of a catastrophic failure of the PDC.

I'm considering geographic load balancing and BGP Anywhere as the two
options.  I'm clear on how the Geo LB works, but have some doubts about
BGPAW as I've never implemented it before and documentation online is
pretty weak to non-existent.

Below is how I believe it should be done.
>From PDC:
	-Advertise CIDR block to all peers w/good metric (0 hop count)
>From BDC:
	-Advertise same CIDR block to all peers w/poor metric (+20 hop
count)

During normal operation, all ASes will route production traffic to PDC.
In the event of catastrophic failure at PDC; PDC advertisements will
cease, BDC route will become the only one on the net and traffic will
route to the BDC.

Questions:
1) Will this work?
2) Other suggestions or alternatives?
3) Any chance that traffic could flow to BDC for any reason?
4) Any internet etiquette I could be ignoring?
5) What would you estimate the failover time would be?
6) Assuming the routers at PDC and BDC pull down full routing table, how
will the receipt of the PDC CIDR advertisement be treated?  BGP rules
say it will be dropped as a routing loop.  What alternatives would I
have if I want to be able to route that CIDR block traffic from the BDC
to the PDC.  Confed?  Cisco conditional advertisements?

Thanks all.  This is the only place I can think of that would have the
expertise to comment.

	-=Vandy=-