[c-nsp] Are there any disadvantages to aggressive netflow aging on a 6509?

[Sergey Nikitin]

You should check:
remote command switch show processes cpu sorted

You will see that NDE - IPV4 process will increase. With very aggressive 
timers you could get a high switch CPU load and there could be some 
disadvantages (what i know is that box could drop some snmp queries at 
about 30-40% of switch CPU load). I didn't try to make it more then 40%, 
so I don't know what will be after that.

HTH

Matthew.Coleman-Hamilton at servicebirmingham.co.uk wrote:
> I've recently enable netflow across the bulk of our 6509 estate and have, 
> after reading various guides, posts and pieces of advice settled on a 
> fairly aggressive set of mls aging timers (the estate is a mixture of 
> Sup720-3B and 3BXL supervisors):-
> mls aging long 64
> mls aging normal 32
> mls aging fast time 16
> ip flow-cache timeout active 1
> ip flow-cache timeout inactive 15
> This seems to be having the desired affect in that TCAM utilisation is not 
> approaching 100% and there doesn't appear to have been any significant 
> increase in CPU utilisation (the EARL NDE task pops up in the process list 
> on occasion when I check but seems to be using single figure % on the 
> whole).
> However, my question is whether there are any disadvantages to aggressive 
> aging, i.e. am I potentially missing flow information or exporting 
> incomplete flow information by moving away from the default settings and 
> aging flows quicker?
> TIA
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