[c-nsp] Quick question on HSRP...

[Phil Mayers]

On 31/12/2013 19:40, Gert Doering wrote:
> Hi,
>
> On Tue, Dec 31, 2013 at 03:59:18PM +0000, Phil Mayers wrote:
>> (Note that changing the HSRP version does not have this property; the
>> old vMAC will be removed from the FDB, and the box won't forward traffic
>> destined to it)
>
> Could someone remind me why I have to change HSRP to v2 to be able to

Not sure about that - maybe some fixed-size field in the HSRPv1 packet? 
Been a while since I looked at it in a sniffer.

> do HSRP for IPv6, only to be then *not* able to run HSRP v4 and v6 in
> the same group anyway?

Yeah, that's a bit odd. After all, you can have HSRP secondary IPs; 
seems odd you couldn't tie the v4 & v6 together on one group.

I do recall HSRPv2 uses different MAC ranges for the IPv4 and IPv6 vMACs.

HSRP has a lot of weird edge cases on Cisco gear. IIRC a lot of them 
relate to the size of the CPU MAC-address receive filter, and other 
tedious crap that wouldn't matter if they moved off CPUs from last 
millenium.

But it's what we've got :o(

In fairness to Cisco, other vendors have blind spots. Juniper makes you 
type a truly tedious amount of config to get VRRP working, though at 
least commit scripts can automate that out of existence.