Odd congestion window behaviour [ was: Draft email to freebsd-net ]

[Randall Stewart]

James Healy wrote:

>>This behaviour seems a little odd to us - can anyone shed some light on
>>it? Our assumption is that the use of the hostcache is designed to
>>increase performance where appropriate by seeding the initial cwnd based
>>on past experience.
>>
>>For this section of code to return a cwnd that is successfully
>>influenced by the hostcache, it would seem that the use of tp->snd_wnd
>>should be avoided when the connection is still being initialised:
>>

Oh, one other comment I have on this..

This is the code that used to be buried with comments about
Alman et.al. says this is ok to do... if I am remembering
right...

I.e. where we keep past connection state and use that
as a reference for the initial cwnd. I asked Mark about
this in the past.. and he said that his paper was
mis-interpreted and this is incorrect behavior. If you
have no connections up to a peer you should not use any
past value for the cwnd...

Thats why we don't do it in SCTP. I know a lot
of O/S's do this.. but it is not sanctified IMO from
the CC experts :-D

R

-- 
Randall Stewart
NSSTG - Cisco Systems Inc.
803-345-0369 <or> 803-317-4952 (cell)