[c-nsp] 7600 DFC upgrade time ?

[Saku Ytti]

On (2008-02-08 13:04 +0100), vince anton wrote:
 
> PFC bus utilisation from 'sh catalyst6000 traffic-meter' on my box shows me
> 8%, presumably 8% utilisation of my 30Mpps. But im guessing the 30Mpps is
> based on lab conditions with 64 byte packets right ?
> 
> So what a fair measure for real world PFC utilisation with internet transit
> traffic, (which is of course not exclusively 64 byte), which can be used to
> indicate thats its time to look at DFCs ?

The pps limit of EARL7 is packet size agnostic, only headers are
transmitted. And actually it's not EARL7 that craps out at ~30Mpps,
it's the bus, the bus is fully saturated with pushing packets
for EARL7 to do it's lookup. 

I think it's like 32btes per cycle, IP is 2 cycles and MPLS is
3 cycles (since it needs IP if you do ECMP). Bus is 62.5MHz, I think.
So from this we'd arrive at:

(62.5*1000000)/2/1000000 = 31.25Mpps IP
(62.5*1000000)/3/1000000 = 20.83Mpps MPLS

This of course assumes that bus will only have headers for lookup,
that is, you don't have classic LC's that use bus for transferring
data.


> 
> 
> 
> Thanks,
> 
> anton
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-- 
  ++ytti