Re: DATACENTER: DataCenter Failover

["nikw@martnet.com" <nikw@martnet.com>]

> Does anyone have any recommendations or details regarding internet
> datacenter network redundancy/failover. We have been tossing around the idea
> of using a single network (say a /20) in two geographic locations. Is it
> possible to advertise this space from two locations to the same and/or
> different upstream providers - like Sprint and UUNet? If a datacenter is
> down/demolished etc... is this a viable way to implement failover and/or
> load sharing? Other solutions we are looking at are F5 BigDNS and Cisco
> Distributed Director. Has anyone used BGP this way? Thanks,

You can do it with with BGP, by making the AS_PATH coming from the
failover location substantially longer by prepending your ASN a few times
in the case of 2 different upstreams.  In the case of a single upstream
you can do it with BGP's MED (Multi Exit Discriminator) metric.

Of course, gets you no load balancing between the two like the F5's
DNS-based solution does.  You will always be using the primary datacenter
until the failover happens.

-nikw