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

[Christopher E. Brown]

Oliver Boehmer (oboehmer) wrote:
> Clinton Work <> wrote on Tuesday, March 22, 2005 4:26 AM:
> 
> 
>>IOS 12.2 doesn't accept that command. I think it was added in a later
>>IOS to answer exactly that question that I had.
> 
> 
> Hmm, which 12.2 releae are you using? "show standby capability" went
> into 12.2(7.6) (CSCuk29834).
> 
> I am not aware of any VIP-like Address Filter (AF) limitation on the
> 7200 platform. "show standby cap" for a C7200-I/O-GE+E in 12.3 shows
> 
> router#show standby capability 
> 7206VXR                                       * indicates hardware may
> support HSRP
>                                               |
> Interface          Type                       H  Potential Max Groups
> Ethernet0/0        134 i82543 (Livengood)     *  ?    (0x600F470C,
> 0x600F46EC)
> GigabitEthernet0/0 27  i82543 (Livengood)     *  ?    (0x600F470C,
> 0x600F46EC)
> 
> some ethernet drivers on the 7200 (like the DEC21140) have an AF limit,
> but they enable promiscuous mode when this limit is hit and perform
> address filtering in the driver software (instead of the hardware)..
> 
> So I don't think you need to use "use-bia" (not that it hurts, IMHO)..
> 
> 	oli

	IIRC, the 7200 w/ 1G I/O has a hsrp limit of 128 virtual macs for HSRP 
service.  (It could be 64 or 256, but IIRC it is 128).  I had to track 
this down sometime back for SUP2/MSFC2 6509s, and found the 7200 info in 
the same table.  (The limit for a SUP2/MSFC2 6509 is BTW 16).


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...


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...)

-- 
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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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