Subject: Re: TCP send buffer free space
To: None <>
From: Wolfgang Rupprecht <>
List: tech-net
Date: 07/10/2001 13:10:32
Dave Gantose writes:
> This is beyond my experience so far, but I will keep it in mind. What all
> might be included in "set everything up" though?

In the program:  

	int tos;

	/* set IP_TOS to request bulk-type packet queuing */
	if (setsockopt(fd, IPPROTO_IP, IP_TOS, (char *) &tos, sizeof(tos)) < 0)
		syslog(LOG_ERR, "setsockopt IPTOS_THROUGHPUT on fails: %m");

If NetBSD is acting as the router/gateway to the low bandwidth link
then set up altq to put packets with IPTOS_THROUGHPUT in a
low-priority queue.  See altq.conf(5).

If some other router is acting as the gateway to the low bandwidth
link then make sure that router puts the packets with IPTOS_THROUGHPUT
set into a low-priority queue.  I understand that Cisco's have had
TOS support for a long time.

The advantage of setting up the infrastructure with several queues
based on the TOS-bits is that lots of things start working better.
One can do other high-bandwidth bulk transfers (like ftp's etc)
without them crowding out interactive traffic.

Wolfgang Rupprecht    <>
Coming soon: GPS mapping tools for Open Systems.