[c-nsp] A Stable BRAS IOS? + performance

[Osama I. Dosary]

Robert E.Seastrom wrote:

>"Osama I. Dosary" <oid at saudi.net.sa> writes:
>
>  
>
>>Hello,
>>
>>We are using Cisco routers (NPE-G1) as a NAS and LNS. No PVCs are
>>terminated on these routers, only L2TP and PPP session termination is
>>going on.
>>
>>We have having difficulting finding a stable IOS to run on these routers.
>>
>>Does anyone know of a good stable IOS they have been using for the
>>same/similar purpose, and recommend?
>>    
>>
>
>I've been using c7200-js-mz.123-8.T4.bin for about six weeks now as an
>LNS; while it's not GD it runs quite nicely on an NPE300 and I believe
>will run on your G1 as well.  Our load peaks at a little over 1600
>simultaneous users, 55% CPU, 50 Mbit aggregate (up + down) traffic
>through router (your mileage will obviously vary since you have a much
>more studly CPU).  CPU load is slightly inflated because of
>outstanding issues with a few hosts that are moving oversized L2TP
>packets that get fragmented and need reassembly to pop the PPPoE frame
>(fragment reassembly is most assuredly *not* in the fast switching
>path).
>
>  
>
On our NPE-G1 (for Dialup) load peaks at ~3000 users, 110Mbps (up+down) traffic and CPU util is about 80%. I feel like we are doing something wrong, according to Cisco docs, this router should be able to handle tons more.

Even when we used to run NPE-300s for dialup, it could not handle more than 900 sessions, with CPU over 90%. What could be the reason? 

We used various IOS versions, without much difference in performance. We noticed that when the B-train version is used we save about 5-10% on CPU cycles. But it is still far from the router specifications.

Could this be a matter of fragmentation of the L2TP packets that could be causing bad performance.
Any ideas?


-Osama