[c-nsp] ASR9k: RIB/FIB convergence

[Bryan Holloway]

Now that is a spicy meatball.


On 8/21/18 9:35 AM, Thomas Schmid wrote:
> Hi,
> 
> to give you an update: TAC finally could reproduce the issue  in the lab. RIB/FIB sync is thwarted when there's a VSM module installed in the chassis (which we have in all 9k chassis).
> 
> Let's see if they can fix it with a SMU ...
> 
> Cheers,
> 
>     Thomas
> 
> 
> Am 02.08.2018 um 11:13 schrieb Thomas Schmid:
>> Hi all,
>>
>> sort of a heads up ...
>>
>> I'd be interested to hear if, and under which circumstances others are seeing this behavior,
>> since the root cause is still unknown.
>>
>> In the beginning there were some anecdotical complaints
>> by customers that they experienced persistent reachability problems to some destinations
>> when we did a scheduled maintenance in our network somewhere else. Further
>> investigations pointed to routing inconsistencies during large RIB changes.
>>
>> To give you some numbers: we found out that in our environment processing 70k BGP changes
>> takes 2-3 min to write the updates to FIB, 700k routes takes 20-30 min!!
>>
>> During that period, RIB and FIB are not consistent with all the nasty consequences:
>> blackholing, routing loops etc.
>>
>> Convergence time seems to be somehow related to the number of eBGP sessions on the
>> box. On routers with less than 200 sessions, convergence time looks ok, from 300+
>> sessions on, things get bad.
>>
>> This affects both XR 5.3.3, 6.2.3 and Typhoon, Tomahawk linecards.
>>
>> TAC/BU are currently working on this, but they have a hard time to find out what's
>> going wrong here. Processing the updates on the RP takes less than 1s,
>> but writing the updates to the LC takes forever ...
>>
>> Thanks,
>>
>>     Thomas
>>
>>
>>
>>
> 
> 
> 
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>