Subject: Re: TCP/Westwood+ support.
To: Kentaro A. Kurahone <>
From: Charles M. Hannum <>
List: tech-kern
Date: 01/01/2005 19:36:42
On Saturday 01 January 2005 19:22, Charles M. Hannum wrote:
> a) A running bandwidth estimate based on the ack rate is kept, and ssthresh
> is set according to that -- in other words, we do exponential growth up to
> the estimated bandwidth, and then linear growth thereafter, whereas Reno
> will just keep trying to increase ssthresh forever.

Actually, that's not quite right.  In Reno, ssthresh is set to half the 
current window (meaning the lower of the congestion window or how much data 
is outstanding at the time of the retransmit) -- so the Westwood behavior is 
potentially more aggressive.  This raises the question of whether it's too 
slow to adapt and might be *too* aggressive, hurting other traffic.  I don't 
see where this has been tested.