From owner-freebsd-net Tue Jun 8 7:15:37 1999 Delivered-To: freebsd-net@freebsd.org Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by hub.freebsd.org (Postfix) with SMTP id E549B14EC3 for ; Tue, 8 Jun 1999 07:14:39 -0700 (PDT) (envelope-from luigi@labinfo.iet.unipi.it) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id NAA00580; Tue, 8 Jun 1999 13:43:59 +0200 From: Luigi Rizzo Message-Id: <199906081143.NAA00580@labinfo.iet.unipi.it> Subject: Re: bridging and multicast (in FreeBSD 3.2-RELEASE) To: alden@math.ohio-state.edu (Dave Alden) Date: Tue, 8 Jun 1999 13:43:59 +0200 (MET DST) Cc: freebsd-net@FreeBSD.ORG In-Reply-To: <19990608100251.B28732@zaphod.mps.ohio-state.edu> from "Dave Alden" at Jun 8, 99 10:02:32 am X-Mailer: ELM [version 2.4 PL23] Content-Type: text Content-Length: 1411 Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > Hi, > Has anyone had any trouble (or success for that matter :-) using the > builtin bridge(4) with multicast packets? I'm running 3.2-RELEASE. > When I run tcpdump on a Sun that is behind the bridge, I get the > following (note that both machinea and machineb are on the 'outside' > of my bridge): hi, this is a known (to me and one other FreeBSD'er in the UK at least :) problem -- the protocol stack does some NTOH*() on the packets passed to the local stack. Because mbufs are shared, if there is a local receiver for multicast traffic this might cause the bridged packets to be scrambled before they go out. A solution (which i think is implemented on my local version but i haven't committed yet 'cause of lack of time) is to do an m_pullup() of enough stuff so that the headers are kept in a separate place. There is a performance penalty of course in doing that, but correctness is more important in these cases... cheers luigi -----------------------------------+------------------------------------- Luigi RIZZO, luigi@iet.unipi.it . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL/FAX: +39-050-568.533/522 . via Diotisalvi 2, 56126 PISA (Italy) http://www.iet.unipi.it/~luigi/ngc99/ ==== First International Workshop on Networked Group Communication ==== -----------------------------------+------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message