using "reserved" IPv6 space

Matt Addison matt.addison at lists.evilgeni.us
Tue Jul 17 11:18:28 UTC 2012


On Jul 17, 2012, at 3:15, Karl Auer <kauer at biplane.com.au> wrote:

> Reading it with a squint: The phrase "packets [...] will be delivered to
> one router on the subnet"  does not specifically exclude the possibility
> that packets will be delivered to more than one router on the subnet.
> Still, I do think it would be a little unreasonable to interpret it
> thus.

After reading some more I see how using subnet-router anycast works.
The anycast address is global in scope so the end host will only learn
1 potential next hop at a time (the routers randomize a delay when
responding to ND for a subnet-router anycast), and perform NUD as
needed to determine if their current router is up or down (RFC4861).

So you can get failover with no FHRP by using subnet-router anycast.
You just won't get sub-second failover.




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