North American Network Operators Group
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Re: Extreme BlackDiamond

  • From: Owen DeLong
  • Date: Mon Oct 13 03:52:52 2003 


This is the kicker and real question: does it require the CPU to forward
regular traffic? I believe the answer is yes, the Extreme is a flow-based
architecture and the first packet of each unique flow (however it is
defined) will need to be processed by the CPU. This is why the problems



Yes, exactly what I'm saying. Flow here is defined as a destination IP
number.




No... Flow is defined as at least the unique combination of source and
destination addresses, and, often, the unique combination of source and
destination IP addresses and port numbers + the layer 4 protocol used.




I can understand how a virus like Welchia can affect a flow-based
architecture like Extremes. I was under the impression that CEF enabled
Cisco gear wouldnt have this problem, but Cisco has instructions on their
webpage on how deal with it and cites CPU usage as the reason. With CEF I
thought the CPU wasn't involved? CEF is perhaps differently implemented
on  different plattforms?




CEF is a flow-based solution much like Extreme's.  There are enhancements
to CEF in some of Cisco's newer products (such as dCEF) which take some of
this off of the CPU.

Owen