[c-nsp] C7200-I/O-GE+E and HSRP group limits

[Christopher E. Brown]

Jon Lewis wrote:
> On Tue, 22 Mar 2005, Christopher E. Brown wrote:
> 
> 
>>Of note, standby group number is used to autogen the roving MAC used by
>>the interface, but you can re-use groupe numbers.
>>
>>IE, dot1q subinterfaces for vlans 2-22 could *all* used standby group
>>10, meaning all roving MACs used by HSRP are the same, but as they are
>>in different VLANs...
> 
> 
> I think you can only reuse group numbers across different interfaces.  At
> least on the platforms I've messed with, dot1q or ISL subinterfaces of a
> single physical interface must have unique hsrp group IDs.
> 
> 
>>The use BIA is only required for older goofy platforms...  It has the
>>nasty side effect of changing the root interface MAC of the routers
>>during handoff.  (Imagine OSPF speaking subnet with a HSRP supported
>>default for a couple non OSPF speakers, bang traffic loss...)
> 
> 
> A workaround I used for this (only supported on some platforms) is to
> configure the HSRP MAC address yourself, and make it the same for all
> vlans/subinterfaces on a given physical interface...and the same on all
> the other hsrp member routers.
> 
> ----------------------------------------------------------------------
>  Jon Lewis                   |  I route
>  Senior Network Engineer     |  therefore you are
>  Atlantic Net                |
> _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________


You are right...  It is the 6509s (native IOS) that let you re-use them 
on vlan interfaces to get around the 16 HSRP mac limit. :(

(Course this means you need to run 6500s/7600s in pairs, but who doesn't)

The 7200 is a no re-use setup, but at least the limit is higher than the 
static route/hsrp interface count I ever want to see.

-- 
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Christopher E. Brown   <chris.brown at acsalaska.net>   desk (907) 550-8393
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IP Engineer - ACS
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