[c-nsp] ASR9k: RIB/FIB convergence

[Thomas Schmid]

Hi Jason,

Am 02.08.2018 um 12:35 schrieb Jason Lixfeld:
> Hi,
> 
> I don’t have that many sessions on any one of my 9Ks, but...
> 
>> On Aug 2, 2018, at 5:13 AM, Thomas Schmid <schmid at dfn.de> wrote:
>>
>> 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!!
> 
> How are you able to see this in the wild? Simply look at the CEF sum on each LC/RP at some interval?
> 

compare 'sh route a.b.c.d/n' with 'sh cef a.b.c.d/n'. It looks like the low ip ranges are processed first (TAC confirmed this), so looking at a high ip number shows it best.

>> 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 ...
> 
> Can you clarify?  Do you mean it takes less than 1s for the RP to successfully feed it’s own FIB after the above topology change (which I assume to be the 700k route topology change), or…?
> 

the BU found, that the rib process on the RP finishes the updates after ca. 1s. Then comes the bcdlv2 process that takes the updates and does the bulk download to the LC. Here the queue is served too slow. They're currently working to find out, what is slowing this down. But this is a moving target and the working hypothesis may change again ...

Regards,

   Thomas