netdev
[Top] [All Lists]

Re: TCP receiver's window calculation problem

To: John Heffner <jheffner@xxxxxxx>
Subject: Re: TCP receiver's window calculation problem
From: Cheng Jin <chengjin@xxxxxxxxxxxxxx>
Date: Thu, 24 Jun 2004 12:18:19 -0700 (PDT)
Cc: "netdev@xxxxxxxxxxx" <netdev@xxxxxxxxxxx>, "fast-support@xxxxxxxxxxxxxx" <fast-support@xxxxxxxxxxxxxx>
In-reply-to: <Pine.NEB.4.33.0406241301010.28506-100000@dexter.psc.edu>
Sender: netdev-bounce@xxxxxxxxxxx
Hi, John,

Thanks for confirming this problem.

> I've run in to this problem, too.  This code prevents advertising more
> rcvbuf space than you are likely to need.  This is good for something like
> an X11 connection, but obviously very bad for the bulk transfer mixed MTU

I would think this is already taken care of at the sender by application
limited cwnd so cwnd wouldn't increase beyond what is being actually used.

> I think the most desirable answer is to not have a hard per-connection
> memory bound, but this is problematic because of denial-of-service
> conerns.

I think having a default limit on tcp memory is acceptable to prevent DoS, 
but when a user increases the memory limit by explicitly setting tcp_rmem,
that should take effect.  The code itself shouldnt pose any limit like it 
does now.

Actually, I am not clear what that window-calculation algorithm is.  Is it 
recommended by some RFC?

Cheng


<Prev in Thread] Current Thread [Next in Thread>