Subject: Re: TCP send buffer free space
To: None <tech-net@netbsd.org>
From: Wolfgang Rupprecht <wolfgang+gnus20010709T105800@wsrcc.com>
List: tech-net
Date: 07/09/2001 11:12:50
gantose@grc.nasa.gov (Dave Gantose) writes:
> I would love to have two separate sockets, but this is a Space Station
> project and the single socket has been dictated to us from on high :(

Wasn't that fact that management was making engineering decisions also
what caused the infamous Challenger explosion?

From an strictly engineering standpoint I'd be tempted to have two
streams with IP_TOS bits set to use IPTOS_THROUGHPUT on the bulk
archived data.  Then set everything up to make sure packets with
IPTOS_THROUGHPUT get last dibs on the remaining bandwidth.  That way
no bandwidth gets wasted, but archived data never crowds out live
data.

Figuring out how many packets are in the kernels local queue doesn't
tell you how many packets are in flight.  You could (and almost
certainly will) have a data backlog at the point where a big pipe gets
attached to a small pipe (typically the WAN link.)

-wolfgang
-- 
       Wolfgang Rupprecht <wolfgang+gnus@dailyplanet.wsrcc.com>
		    http://www.wsrcc.com/wolfgang/
Coming soon: GPS mapping tools for Open Systems. http://www.gnomad-mapping.com/