From owner-freebsd-questions Sat Sep 7 9: 1:58 2002 Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B8AEB37B400 for ; Sat, 7 Sep 2002 09:01:54 -0700 (PDT) Received: from smtp.infracaninophile.co.uk (happy-idiot-talk.infracaninophile.co.uk [81.2.69.218]) by mx1.FreeBSD.org (Postfix) with ESMTP id A521243E65 for ; Sat, 7 Sep 2002 09:01:53 -0700 (PDT) (envelope-from m.seaman@infracaninophile.co.uk) Received: from happy-idiot-talk.infracaninophile.co.uk ([IPv6:::1]) by smtp.infracaninophile.co.uk (8.12.6/8.12.6) with ESMTP id g87G1pUc000921; Sat, 7 Sep 2002 17:01:51 +0100 (BST) (envelope-from matthew@happy-idiot-talk.infracaninophile.co.uk) Received: (from matthew@localhost) by happy-idiot-talk.infracaninophile.co.uk (8.12.6/8.12.6/Submit) id g87G1eBV000916; Sat, 7 Sep 2002 17:01:40 +0100 (BST) Date: Sat, 7 Sep 2002 17:01:40 +0100 From: Matthew Seaman To: Robert Tan Cc: "freebsd-questions@FreeBSD. ORG" Subject: Re: tcpdump VJC Message-ID: <20020907160140.GA274@happy-idiot-talk.infracaninophi> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.1i Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Sat, Sep 07, 2002 at 01:06:48PM +0200, Robert Tan wrote: > What does the following tcpdump show: > > 13:02:36.121981 VJNC 103: > 13:02:36.122835 VJC 22: > 13:02:36.192492 VJC 12: > 13:02:36.199864 VJC 49: > 13:02:36.200565 VJC 26: > 13:02:36.288607 VJC 9: > 13:02:36.377856 VJC 38: > 13:02:36.378595 VJC 18: > 13:02:36.445868 VJC 22: > 13:02:36.446576 VJC 18: > 13:02:36.529103 VJC 103: > 13:02:36.530225 VJC 20: > 13:02:36.778853 VJC 1033: > 13:02:36.909851 VJC 1031: > 13:02:36.911865 VJC 13: > 13:02:37.039852 VJC 1031: > 13:02:37.169483 VJC 1031: > 13:02:37.171447 VJC 11: > 13:02:37.298975 VJC 1031: > 13:02:37.428347 VJC 1031: > 13:02:37.430320 VJC 11: > 13:02:37.557605 VJC 1031: > 13:02:37.691854 VJNC 1068: > 13:02:37.693839 VJC 14: > 13:02:37.822226 VJC 1034: VJC is Van Jacobsen Compressed TCP/IP traffic, VJNC is Van Jacobson Uncompressed TCP/IP traffic, both passing over a PPP connection. It's a method of optimizing traffic over slow links by eliding redundant portions of packet headers -- hence you often see it refered to as "Van Jacobsen Header Compression". Far more detail than you ever wanted to know my be obtained at http://www.faqs.org/rfcs/rfc1144.html Cheers, Matthew -- Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks Savill Way Marlow Tel: +44 1628 476614 Bucks., SL7 1TH UK To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message