RE: Failover IPv6 with multiple PA prefixes (Was: IPv6 fc00::/7 — Unique local addresses)

[gbonser at seven.com (George Bonser)]

> From: Jeroen Massar > Sent: Thursday, October 21, 2010 9:57 AM
> To: Allen Smith
> Cc: NANOG list
> Subject: Failover IPv6 with multiple PA prefixes (Was: IPv6 fc00::/7 ?
> Unique local addresses)
> 
> [Oh wow, that subject field, so handy to indicate a topic change! ;) ]
> 
> Short answer: you announce both PA prefixes using Router Advertisement
> (RA) inside the network. You pull the RA when a uplink goes
> down/breaks.

That assumes importing some sort of routing state into your RA config.  Sort of a conditional RA.  Can that be done today by anyone?

> Sessions break indeed, but because there is the other prefix they fall
> over to that and build up new sessions from there.

This still doesn?t address breakage that happens AFTER your link to your upstream.  What if your upstream has a peering issue or their peer has a peering issue?  How do you detect that the distant end has a route back to that prefix but doesn't to the other?  You can't.