Subject: Re: kern/9085: enabling RFC1323 support causes some TCP connectionsto stall
To: David Brownlee <>
From: Mark Allman <>
List: tech-net
Date: 02/28/2000 13:00:43
Sorry to be piling onto this thread very late.  I am drowning in
email and it has taken a cross-country flight to clean all this old
stuff out...

My hit is that rfc1323 should probably be off by default, but for a
different reason than others have stated.  My argument is that
typically we don't need rfc1323 support because typically we don't
send ~128KB of stuff over a TCP connection, so there is no way we
can build cwnd anywhere near 64KB (i.e., max without rfc1323
support).  So, why burn the bits on timestamps?  (Especially on low
bandwidth links).  A couple other points...

  * A per interface rfc1323 knob sounds like a good idea.  

  * I would be in favor of raising the default socket buffer sizes
    to 64KB by default.  In other words, let the network dictate
    performance rather than some arbitrary limit imposed by the host
    (And, more generally, adding autotuned socket buffers, ala the
    SIGCOMM98 paper from PSC). 

  * And, while I am potificating...  NetBSD needs a SACK-based
    loss recovery algorithm (he says hoping someone else has cycles
    to implement that!).