On Fri, 17 Feb 2006, Todd Vierling wrote:
On Thu, 16 Feb 2006, Warren Kumari wrote:
If your primary is connected to ISP_A and the backup is connected to ISP_B, customers connected to ISP_B MAY still flow to your backup DC (ISP_B will probably set local preference on all customer routes - you should be able to override this behavior with communities but not all providers support this (or honor it 100% of the time!))
And in addition to that, even multihomed customers of ISP_B may choose the prepended route for a number of different reasons; for instance, ISP_B might be a cheaper pipe for them, or there may be a smart-ish routing device or scheme in play that overrides normal BGP decision making.
I might be crazy, but couldn't you just prepend the route enough to effectively poison it at ingress to 'backup-isp' ? so they kept chosing the remote path and never really accept the route from local until the remote path is gone?