Subject: Re: tcp_do_rfc1323 vs Linux - any solid understanding?
To: Peter Seebach <>
From: Ken Hornstein <>
List: current-users
Date: 06/09/1996 23:35:00
>Does anyone know *why* the rfc 1323 option produces pessimal network
>Symptom:  Assume two NetBSD systems with rfc 1323 enabled.  Connect
>one via ethernet to a Linux box, and the other via ppp to the same
>Linux box.
>PPP connection to Linux will be excellent and responsive.  Ethernet
>likewise.  But the connection between the NetBSD boxes is pessimal.

This _has_ been discussed before, honest :-)

If a host doesn't support any of the IP options in RFC 1323, they won't
be used at all, and won't affect anything.  This is why connections to the
Linux box work fine.

The reasons that the IP options used in RFC 1323 cause problems are generally

- Some boxes have "less than optimal" IP implementations, and just can't
  deal with them.  For example, some older Annexes would crash upon getting
  packets with IP options set.

- IP options interact badly with some versions of PPP when VJ header
  compression is enabled.  For example, Telebit Netblazers will eat packets
  that have IP options set if you use PPP and VJ header compression.

I would try two things:

- Turn off VJ header compression on the PPP connection
- Turn off rfc1323 via sysctl.

There's really nothing else you can do (other than fix the bugs in the other
systems :-) ).