[f-nsp] CAM and ip net-aggregate or ip supernet aggregate - does it help to free the cam up ? WAS:AW: cam strangeness

Gunther Stammwitz gstammw at gmx.net
Mon Mar 6 10:48:32 EST 2006

Hello Kristian,

That sounds horrible! Didn't you open a case with TAC/technical-support?
Which management module exactly are you using? Is it ironcore or jetcore and
what are your settings regarding the cam-partition, the supernet-aggregation
and the ip net-aggregate?

I have seen some strange behaviour too on our jetcore-module:
When enabling the ip supernet aggregate-command which  the cpuload jumped
from 10 to 20 or even 25% so we disabled it again. The interestint thing was
that the cam was freed up to ~50% or something like that.

The next try was to enable ip net-aggregate and the load jumped from 10% to
99 which was rather bad and caused a lot of packet loss and so on
(Trouble!). The solutions was to use ip net-aggregate X where X is a number
of let's say 10 or 30 so that the aggregation-process won't try to compres
the cam every one second which is the default behaviour but rather every 10
or maybe even 30 seconds.
This reduced the load to 5% and we can't even notice the aggregation-process
that should run from time to time. No packetloss no nothing

Our current cam-usage is looking like this:
#show cam ip 1/1 stat 
CAM IP statistics:      free entries    total entries
           level1:      8670            28672
           level2:      1147            2048
           level3:      1960            2047
I'm not really sure that it was before but I think to remember that without
any aggregation at all there were about 20000 entries (layer1) free but I'm
not sure. We're using bgp with 3 full views.

On another router that I'm managing there's a ironcore mgmt-card, 2 full
bgp-views and some peers and most of the traffic is following the default
route and the usage is looking like this:  
show cam ip 1/1 stat
CAM IP statistics:      free entries    total entries
           level1:      4072            8192
           level2:      1726            2048
           level3:      2020            2047

What do the others say: does aggregation help and does the cam usually fill
up in an isp enviorment?
What about situation with gameserver-providers or voip which causes a lot of


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