Extreme congestion (was Re: inter-domain link recovery)

Mikael Abrahamsson swmike at swm.pp.se
Thu Aug 16 16:29:19 UTC 2007

On Thu, 16 Aug 2007, michael.dillon at bt.com wrote:

> How many people have noticed that when you replace a circuit with a 
> higher capacity one, the traffic on the new circuit is suddenly greater 
> than 100% of the old one. Obviously this doesn't happen all the time, 
> such as when you have a 40% threshold for initiating a circuit upgrade, 
> but if you do your upgrades when they are 80% or 90% full, this does 
> happen.

I'd say this might happen on links connected to devices with small buffers 
such as with a 7600 with lan cards, foundry device or alike. If you look 
at the same behaviour of a deep packet buffer device such as juniper or 
cisco GSR/CRS-1 the behaviour you're describing doesn't exist (at least 
not that I have noticed).

Mikael Abrahamsson    email: swmike at swm.pp.se

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