number of hops != performance

Tue Nov 5 19:22:46 UTC 2002

On Tue, Nov 05, 2002 at 06:13:37PM +0100, Mikael Abrahamsson wrote:
> 
> We have competitors that are claiming that their network is superior to
> ours (salesdroids to customers) because they have fewer L3 hops in their
> network. I see this "fact" pop up in customer questions all the time. 
> 
> I can see that L3 hops adds latency if a network is built on slow (2meg
> for instance) links, but at gigabit speeds, L3 hops adds microseconds in
> latency (if you use equipment that forward using hardware-assisted
> forwarding, but as far as I know there are no routers out there nowadays
> that doesnt).

Of course L3 forwarding is not by itself "bad" for the packets. However...
If you have a network with "excessive" hops (for some definition of
excessive), it probably means one or more of the following:

A) you have a poor (or at least non-elegant) network design.
B) you have more places for things to go wrong in both hardware and
   software.
C) you're busy gratifying your architectural ego instead of designing
   the simplest thing possible which gives you the necessary performance 
   and reliability.
D) you're buying so much unnecessary hardware that you are either not 
   not financially healthy or you're not passing on as much savings as you
   could be to your customer.

Now while I'm sure that you don't fit into that definition of "excessive",
I can think of a few people who do, and they try to use that "but more L3
hops are never bad" argument.

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
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