From owner-freebsd-hackers Fri Aug 28 08:43:29 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id IAA04001 for freebsd-hackers-outgoing; Fri, 28 Aug 1998 08:43:29 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from mail.promo.de (mail.Promo.DE [194.45.188.65]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id IAA03957 for ; Fri, 28 Aug 1998 08:42:26 -0700 (PDT) (envelope-from stefan@promo.de) Received: from d254.promo.de (d254.Promo.DE [194.45.188.254]) by mail.promo.de (8.8.8/8.8.8) with ESMTP id RAA00671; Fri, 28 Aug 1998 17:34:27 +0200 (CEST) Date: Fri, 28 Aug 1998 17:37:40 +0200 From: Stefan Bethke To: sbabkin@dcn.att.com cc: hm@kts.org, freebsd-hackers@FreeBSD.ORG Subject: RE: TCP checksum errors resulting from IP addr change Message-ID: <1374590.3113314660@d254.promo.de> In-Reply-To: Originator-Info: login-id=stefan; server=mail X-Mailer: Mulberry Demo (MacOS) [1.4.0b2, s/n Evaluation] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Fre, 28. Aug 1998 11:15 Uhr -0400 sbabkin@dcn.att.com wrote: > Sorry for a stupid question, but may it be related somehow to the > header compression mode ? I'm not sure about the PPP compression but > for SLIP these symptoms would clearly indicate that one side is > working with compression while another one is working without > compression. The SLIP compression works on a per-connection > basis, so datagram packets and the TCP SYN packets are always not > compressed - so ping works and you can establish the connection, > but following TCP packets have their headers compressed by > removing the redundant information that can be restored from previous > TCP packets, so they would appear broken if the other side works > in other mode. It may be that PPP is using something like this > (and it also has 2 different compression modes). You could be right, but in this case, you aren't. It's no question of Van Jacobsen TCP header compression (this isn't particular to SLIP, but used in PPP indeed), but instead of wrong IP adresses in the headers. VJ compression works in isppp, AFAIK. Stefan -- Stefan Bethke Promo Datentechnik | Tel. +49-40-851744-18 + Systemberatung GmbH | Fax. +49-40-851744-44 Eduardstrasse 46-48 | e-mail: stefan@Promo.DE D-20257 Hamburg | http://www.Promo.DE/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message