On 2010-10-21 21:35, George Bonser wrote: > > >> 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?
Should be possible with any vendor that supports IPv6. If you take a vendor C box and the box dies (just pull the power plug to test this or configure it with something funky ;), Neighbor Discovery starts failing and every IPv6 stack that I know will deprecate the routes over that gateway, and stuff fails over. For 'production usage', let your monitor script login to your router, whatever brand/make/model that is, and unconfigure the RA or heck kill the radvd daemon. >> 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. Solve it the way you solve it with PI: - Get an SLA with every destination you want to reach Indeed, that is a more or less unsolveable problem. You can of course monitor all the destinations you want to reach and based on that to use the prefix or not. Greets, Jeroen
