[c-nsp] IPv6 first-hop redundancy: short-lived RA or FHRP?

[Peter Rathlev]

On Tue, 2012-10-23 at 19:15 +0100, Phil Mayers wrote:
> HSRPv6 gives you access to the "track" stuff which can be useful to have 
> more explicit control over how you failover and when.

Right, that's a rather good point.

> In addition, HSRP packets flow between routers, not router->hosts. The 
> implications of missing a few RAs in a row with very short-lived RAs are 
> unclear, and possibly undesirable.

I actually thought that router->hosts was better overall. I can't think
of an example right now but I'm almost certain I've seen or thought of
scenarios where that would cope with some errors that router->router
wouldn't catch. But that's probably academic if anything. :-)

> We use HSRPv6 on sup720 and are happy with it. We do however use "ipv6 
> nd prefix" to lower the prefix lifetime, because I think the RFC 
> defaults are absurd.

AFAICT the default lifetime is 30 days, at least for 15.0(1)SY1. I'm not
sure I see the problem with that. I consider it equivalent to a DHCP
lease time of 30 days, something we only not do because of address
depletion, right? Or am I missing something?

-- 
Peter