[63908] in North American Network Operators' Group
Re: Extreme BlackDiamond
daemon@ATHENA.MIT.EDU (Owen DeLong)
Mon Oct 13 03:51:05 2003
Date: Mon, 13 Oct 2003 00:50:20 -0700
From: Owen DeLong <owen@delong.com>
To: Mikael Abrahamsson <swmike@swm.pp.se>, nanog@merit.edu
In-Reply-To: <Pine.LNX.4.44.0310130739140.6300-100000@uplift.swm.pp.se>
Errors-To: owner-nanog-outgoing@merit.edu
>> 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
