number of hops != performance

Mikael Abrahamsson swmike at swm.pp.se
Tue Nov 5 17:13:37 UTC 2002


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).

Does anyone have a nice reference I can point to to once and for all state
that just because a customer has 6-8 L3 hops within our network (all at
gigabit speeds or higher) that doesnt automatically mean they are getting
bad performance or higher latency.

Hiding the L3 hops in a MPLS core (or other L2 switching) doesnt mean
customers are getting better performance since equipment today forwards 
just as quickly on L3 as on L2.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se




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