From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: IPv4 multicast and mac-vlans acting weird on 3.0.4+ Date: Wed, 05 Oct 2011 21:54:09 +0200 Message-ID: <1317844449.3457.3.camel@edumazet-laptop> References: <4E8C89EE.3090600@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev To: Ben Greear Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:63989 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933233Ab1JETyW (ORCPT ); Wed, 5 Oct 2011 15:54:22 -0400 Received: by wyg34 with SMTP id 34so2077442wyg.19 for ; Wed, 05 Oct 2011 12:54:21 -0700 (PDT) In-Reply-To: <4E8C89EE.3090600@candelatech.com> Sender: netdev-owner@vger.kernel.org List-ID: Le mercredi 05 octobre 2011 =C3=A0 09:46 -0700, Ben Greear a =C3=A9crit= : > This is on a hacked 3.0.4 kernel... >=20 > I am seeing an issue where an IPv4 mcast receiver will not receive > a 1473 or larger byte mcast message, but will receive a 1472. The di= fference > being that 1473 ends up being two packets on the wire. It works on > 802.1Q VLANs, VETH interfaces and real Ethernet. It does not work > on a mac-vlan hanging off the VETH. >=20 > I see packets received on the macvlan in tshark, and they appear corr= ect. No > obvious errors in the macvlan port stats or netstat -s, > and the 'ss' tool doesn't appear to support UDP sockets at all. >=20 > So, I'm about to go digging into the code, but if anyone has any > suggestions for places to look, please let me know! >=20 Well, problem is defragmentation and macvlan cooperation. Multicast messages are broadcasted on all macvlan ports. But IP defrag will probably deliver a single final frame. We probably need to handle defrag in macvlan before broadcasting to all ports.