* scg@gibbard.org (Steve Gibbard) [Mon 05 Jul 2004, 10:19 CEST]: [..]
The performance arguments are probably more controversial. The arguments are that shortening the path between two networks increases performance, and that removing an extra network in the middle increases reliability. The first argument holds relatively little water, since it's in many cases only the AS Path (not really relevant for packet forwarding performance) that gets shortened, rather than the number of routers or even the number of fiber miles.
"Not really"? Not always, perhaps. But it's more the rule than the exception, I think.
If traffic goes from network A, to network A's router at an exchange point, to network C, that shouldn't be different performance-wise from the traffic going from network A, to Network B's router at the exchange point, to Network C.
Except that, due to "peering games" some companies tend to engage in, the exchange point where A and B exchange traffic may well be in a different country from where A, C and their nearest exchange point is.
Assuming none of the three networks are underprovisioning, the ownership of the router in the middle shouldn't make much difference. The reliability argument is probably more valid -- one less network means one less set of engineers to screw something up, but the big transit networks tend to be pretty reliable these days, and buying transit from two of them should be quite safe.
The correct phrasing is indeed "one less network" and not "one less router." It's rarely one device in my experience. -- Niels.