[c-nsp] ASR 1002-X FIB scalability

[Beck, Andre]

Re,

On Tue, May 28, 2013 at 11:45:11AM +0200, Beck, Andre wrote:
> asr1002-x#sh mem sum
>                 Head    Total(b)     Used(b)     Free(b)   Lowest(b)  Largest(b)
> Processor  7F5AF4B0C010   7056007904   6277142588   778865316   778855216   778195964
> 
> 
> So yes, the box clearly can digest 3M routes down to the FIB.

At least it can when running 3.7.xS (I tested x=0 and x=3). When it comes
to 3.8.2S and 3.9.0S, all of a sudden IOSd is getting less RAM:

3.7.x:
cisco ASR1002-X (2RU-X) processor with 6890313K/6147K bytes of memory.                                                              
3.9.0:
cisco ASR1002-X (2RU-X) processor with 4771326K/6147K bytes of memory.                                                              
Needless to say, when flooding the latter with the same 3.34M prefixes
that the former can deal with, it explodes due to the IOSd running out
of memory. Why in the world was the IOSd process memory reduced by 30%
compared to a previous version? I didn't see anything in the release
notes that would warn about this. Of course nobody is running with such
large FIBs at the moment and the ressources have probably been rerouted
to processes outside IOSd needing them more urgently, but I would still
expect a note about it (say, "if your IOSd currently exceeds a process
memory usage of 4GB for whatever reason, be wary").

It's also still a shame this can't be configured by the user (there was
a thread here in 2011 about this hitting even more badly on a 4GB ASR1001).
I just don't like how more than 2GB of my preciously expensive 16GB just
disappeared. Specifically when that RAM is still 44% free according to
"show platform software status control-processor"...

HTH,
Andre.
-- 
                    Cool .signatures are so 90s...

-> Andre Beck    +++ ABP-RIPE +++      IBH IT-Service GmbH, Dresden <-