[131238] in North American Network Operators' Group
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daemon@ATHENA.MIT.EDU (Jeroen Massar)
Thu Oct 21 15:52:07 2010
Date: Thu, 21 Oct 2010 21:51:49 +0200
From: Jeroen Massar <jeroen@unfix.org>
To: George Bonser <gbonser@seven.com>
In-Reply-To: <5A6D953473350C4B9995546AFE9939EE0B14C416@RWC-EX1.corp.seven.com>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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
