From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowmini Varadhan Subject: Re: IPv6 nexthop for IPv4 Date: Thu, 26 Mar 2015 10:53:56 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev To: =?UTF-8?Q?Bj=C3=B8rnar_Ness?= Return-path: Received: from mail-wi0-f175.google.com ([209.85.212.175]:38149 "EHLO mail-wi0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752161AbbCZOx5 convert rfc822-to-8bit (ORCPT ); Thu, 26 Mar 2015 10:53:57 -0400 Received: by wibgn9 with SMTP id gn9so89033306wib.1 for ; Thu, 26 Mar 2015 07:53:56 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Mar 26, 2015 at 10:39 AM, Bj=C3=B8rnar Ness wrote: >>> ip route add 10.0.0.0/16 via fe80::225:90ff:fed3:bfb4/64 dev sfp0 >> >> Trying to understand what the desired behavior is, for the route >> above: if I send a packet from 10.0.0.1 to 10.0.0.2, you want the ds= t-mac >> to be the mac address of e80::225:90ff:fed3:bfb4??? > > Absolutely, correct. What if the current node does not want to support ipv6? This sounds pretty "creative", if this can work, you might as well make the nexthop= to be the L2 address of the gw. > Basically because you either added the route manually, or it was prov= ided > by fe80::225:90ff:fed3:bfb4 itself via some routing protocol (MP-BGP) > > This will be the same as any other route. How do you know it forwards= traffic.. because you would be running a routing protocol that manages reachabili= ty of the gw and the route. RIP, OSPF, BGP etc all have a lot of mechanism= s to monitor liveness of the route and of the nexthop, which has to be of the same address family as the route itself. > > In large routed setups, address management in general and lack of IPv= 4 addresses > can become a big hassle. Beeing able to get a ipv6 neighbor for a ipv= 4 > route would > make this process a lot simpler. Yes, that's the motivation behind all the tunneling/transition mechanis= ms in the various ipv6 working groups. --Sowmini