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 13:01:45 -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> 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 nlpi129.sbcis.sbc.com ([207.115.36.143]:35186 "EHLO nlpi129.prodigy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932299Ab0FBSBs (ORCPT ); Wed, 2 Jun 2010 14:01:48 -0400 In-Reply-To: <1275500802.2519.7.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2 Jun 2010, Eric Dumazet wrote: > Here is the patch I cooked to account for RP_FILTER errors in multicast > path. > > I will complete it to also do the unicast part before official > submission. > > Christoph, the official counter would be IPSTATS_MIB_INNOROUTES Great. Thanks. > ipSystemStatsInNoRoutes OBJECT-TYPE > SYNTAX Counter32 > MAX-ACCESS read-only > STATUS current > DESCRIPTION > "The number of input IP datagrams discarded because no route > could be found to transmit them to their destination. add "or because the rp_filter rejected the packet"? In the case of MC traffic you dont really need a route. 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). 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. So you could add also "because of breakage in the rp_filter (rp_filter ignores the multicast subscription tables when determining the correct reverse path of the packet)"