[46671] in North American Network Operators' Group
Re: Load balancing in routers
daemon@ATHENA.MIT.EDU (Iljitsch van Beijnum)
Mon Apr 8 12:04:03 2002
Date: Mon, 8 Apr 2002 18:03:40 +0200 (CEST)
From: Iljitsch van Beijnum <iljitsch@muada.com>
To: Paul Vixie <vixie@vix.com>
Cc: <nanog@merit.edu>
In-Reply-To: <g3y9fygqnb.fsf@as.vix.com>
Message-ID: <20020408175209.Y76423-100000@sequoia.muada.com>
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Errors-To: owner-nanog-outgoing@merit.edu
On 8 Apr 2002, Paul Vixie wrote:
> > I seem to remember fast switching was per-destination, and CEF was
> > round robin. But it seems CEF is now per-destination as well in IOS 12.2.
> > Round robin is optional.
> CEF is flow-hashed, and the hash seems to include both source and
> destination, and seems to include the port numbers. This is by observing
> the behaviour of flows hitting various members of the F.ROOT-SERVERS.NET
> set, each of whom sends F's address to several upstream routers using OSPF.
> CEF works like a charm -- the load is never split by more than 45-55 and
> that's damn good for wire speed hashing in my view.
> We used CEF in 11.x and it behaved the same way. It was never round-robin
> in any way we could observe.
You're right. I was thinking of process switching.
According to:
http://www.ils.unc.edu/dempsey/186s00/reorderingpaper.pdf
packet reordering at MAE East was extremely common a few years ago. Does
anyone have information whether this is still happening?
