From owner-freebsd-net@FreeBSD.ORG Tue Apr 22 10:49:18 2003 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2BB3937B401 for ; Tue, 22 Apr 2003 10:49:18 -0700 (PDT) Received: from relay.pair.com (relay.pair.com [209.68.1.20]) by mx1.FreeBSD.org (Postfix) with SMTP id 0942C43FAF for ; Tue, 22 Apr 2003 10:49:17 -0700 (PDT) (envelope-from silby@silby.com) Received: (qmail 87774 invoked from network); 22 Apr 2003 17:49:16 -0000 Received: from niwun.pair.com (HELO localhost) (209.68.2.70) by relay.pair.com with SMTP; 22 Apr 2003 17:49:16 -0000 X-pair-Authenticated: 209.68.2.70 Date: Tue, 22 Apr 2003 00:45:17 -0500 (CDT) From: Mike Silbersack To: Don Lewis In-Reply-To: <200304221712.h3MHCTXB027263@gw.catspoiler.org> Message-ID: <20030422004104.Q523@odysseus.silby.com> References: <200304221712.h3MHCTXB027263@gw.catspoiler.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-net@FreeBSD.org Subject: Re: IP fragmentation disagreement between current and stable X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 Apr 2003 17:49:18 -0000 On Tue, 22 Apr 2003, Don Lewis wrote: > will contain 222 bytes of data. With a 14 byte Ethernet header and a 20 > byte IP header, that just fits into one 256 byte mbuf. I wonder if > there is a divide by 4 to calculate the number of words, and the > > Could this be a driver problem instead of a problem in the stack itself? > Both ends are fxp cards. A similar problem was found with Via Rhine chips, where having multiple packets exactly fill up the internal FIFO seemed to cause those packets to be dropped. Naturally, this only cropped up with fragmented ping packets of certain lengths. We never bothered patching it because, well, no clear solution presented itself, and it wouldn't occur in normal usage. (Actually, changing from store and forward back to smaller DMA sizes might have fixed it, I'm not sure.) So, I would not rule out the possibility of a driver / chipset bug. Mike "Silby" Silbersack