From mboxrd@z Thu Jan 1 00:00:00 1970 From: YOSHIFUJI Hideaki Subject: Re: icmpv6: issue with routing table entries from link local addresses Date: Tue, 13 Sep 2016 12:01:18 +0900 Message-ID: <4986ff01-5157-390c-7d58-764e17b67322@miraclelinux.com> References: <20160912142732.GI26782@targo.k4n.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: hideaki.yoshifuji@miraclelinux.com, =?UTF-8?Q?Andreas_H=c3=bcbner?= , netdev , "d. caratti" , Sowmini Varadhan To: Sowmini Varadhan , Hannes Frederic Sowa Return-path: Received: from mail-pf0-f172.google.com ([209.85.192.172]:33711 "EHLO mail-pf0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750953AbcIMDBX (ORCPT ); Mon, 12 Sep 2016 23:01:23 -0400 Received: by mail-pf0-f172.google.com with SMTP id g202so58836862pfb.0 for ; Mon, 12 Sep 2016 20:01:22 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Sowmini Varadhan wrote: > On Mon, Sep 12, 2016 at 1:26 PM, Hannes Frederic Sowa > wrote: >> Hello, >> >> On 12.09.2016 16:27, Andreas Hübner wrote: > >>> >>> I have the following setup: >>> - 2 directly connected hosts (A+B), both have only link local addresses >>> configured (interface on both hosts is eth0) > : >>> fe80::/64 dev eth1 proto kernel metric 256 >>> fe80::/64 dev eth0 proto kernel metric 256 > : >>> The issue I currently have is, that the echo reply that host B should >>> generate is never sent back to host A. If I change the order of the >>> routing table entries on host B, everything works fine. >>> (host A is connected on eth0) > : >> This shouldn't be the case. We certainly carry over the ifindex of the >> received packet into the routing lookup of the outgoing packet, thus the >> appropriate rule, with outgoing ifindex should be selected. > > Like Hannes, I too would first check "is B sending out the echo-resp? on > which interface?". > > But a couple of unexpected things I noticed in linux: the link-local > prefix should have a prefixlen of /10 according to > http://www.iana.org/assignments/ipv6-address-space/ipv6-address-space.xhtml > but "ip -6 route show" lists this as a /64.. Do not be confused; link-local address for ethernet is described by IPv6 over FOO document (e.g., RFC2464 for Ethernet). The address (fe80::/64 for Ethernet, for example) is defined inside the link-local scope unicast address space (/10). -- Hideaki Yoshifuji Technical Division, MIRACLE LINUX CORPORATION