From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Subject: Re: [PATCH] IP: Increment INADDRERRORS if routing for a packet is not successful Date: Wed, 2 Jun 2010 13:59:21 -0500 (CDT) Message-ID: References: <1275496439.2725.203.camel@edumazet-laptop> <20100602.101258.134121018.davem@davemloft.net> <20100602.103102.121237521.davem@davemloft.net> <1275500802.2519.7.camel@edumazet-laptop> <1275504070.2519.12.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: David Miller , netdev@vger.kernel.org, shemminger@vyatta.com To: Eric Dumazet Return-path: Received: from nlpi157.sbcis.sbc.com ([207.115.36.171]:45412 "EHLO nlpi157.prodigy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757951Ab0FBS70 (ORCPT ); Wed, 2 Jun 2010 14:59:26 -0400 In-Reply-To: <1275504070.2519.12.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2 Jun 2010, Eric Dumazet wrote: > > In my particular case it is a weird corner case for the rp_filter. > > > > Two NICs are on the same subnet. Different multicast groups are joined > > on each (Using two NICs to balance the MC load since the drivers have > > some multicast limitations and having different interrupt lines for each > > NIC is also beneficial). > > > > yeah, I know about this problem, and am working on it too... > > > The rp_filter rejects all multicast traffic to the subscriptions on the > > second NIC. I guess this is because the source address of the MC traffic > > (on the same subnet) is also reachable via the first NIC. > > > > Its clearly a case were rp_filter should be set to 2, dont you think ? The rp_filter is rejecting traffic coming into a NIC for which the kernel has a multicast join list that indicates that this traffic is expected on this NIC. You could consult the MC subscription list to verify that the traffic is coming into the right NIC. In the MC case the user can explicitly specify through which NIC the traffic is expected. See IP_ADD_MEMBERSHIP.