[c-nsp] HSRP Groups on ASR1k

[Benjamin Lovell]

See inline BL>


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          .            .          Benjamin Lovell
          |            |          AS Video Practice
         |||          |||         Cisco Customer Advocacy
       .|||||.      .|||||.       Research Triangle Park, NC
    .:|||||||||:..:|||||||||:.    Email:  belovell at cisco.com
             cisco            desk:919.392.8255 cell:203.509.1562
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On Sep 28, 2010, at 12:48 PM, Phil Mayers wrote:

> On 28/09/10 17:35, Benjamin Lovell wrote:
>> I haven't looked into this on the ASR1K but what the message is
>> telling you is that the NIC can only program 28 MAC addresses and you
>> have used up the limit. If you add more sub-interfaces with HSRP then
>> bad things will start to happen. Drops, punt to CPU, not sure as I
>> have not looked into it on this platform but nothing good.
> 
> Is this right?
> 
> Isn't the HSRP MAC the same for a given group number, regardless of which sub-int?
> 
> We run all our interfaces (not ASR1k though) in "standby group 0"
BL> It varies by platform. The 3K series switches for example also use the VLAN ID and will give you 256(i think) unique MACs even if using the same group ID. Either way using the same or no group ID is defiantly not Cisco's recommendation. 
> 
>> 
>> This could be a software limitation that was addressed or is planed
>> to be addressed in later code releases or it could be a hard limit of
>> the NIC used on the SPAs. I would open a case with the TAC to have
>> them talk to the devs about this and see if it will be important to
>> you.
>> 
>> BTW - not clear on the part where you said you are using HSRP groups
>> 1 and 2 on the customer sub-ints. You should use a unique standby
>> group for each HSRP instance. If you are not this *may have something
>> to do with your problem.
> 
> Why? Using a different standby group per sub-int will surely definitely run you over the mac receive filter size limit? What's the problem using the same group number on different interfaces?

BL>It's certainly possible/likely but this is really a matter of platform knowledge about how the ASR 1K does MAC filtering / HSRP MAC assignment. I am not that deep into the ASR 1K platform and unless one is it would not be wise to jump to conclusions. 
 

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