From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sowmini Varadhan Subject: Re: IPv6 nexthop for IPv4 Date: Thu, 26 Mar 2015 10:29:14 -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-wg0-f45.google.com ([74.125.82.45]:34091 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751382AbbCZO3P convert rfc822-to-8bit (ORCPT ); Thu, 26 Mar 2015 10:29:15 -0400 Received: by wgs2 with SMTP id 2so66487914wgs.1 for ; Thu, 26 Mar 2015 07:29:14 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Mar 26, 2015 at 9:16 AM, Bj=C3=B8rnar Ness wrote: > Hello, hope this is the right place to ask. > > Does anyone know if there is work beeing done in natively supporting > IPv6 nexthops for IPv4? What problem are you trying to solve? Do you want to tunnel your ipv4 packet through IPv6? there are a number of tunneling mechanisms in linux for this. > > I know that "some" Linux switch software company is working on this, = but > I am afraid the functionality will be more of a "hack". > > The benefit of this is stateless configuration (rfc5549), using IPv6 = link-local > neighbor address as IPv4 nexthop, beeing able to do for example: > > 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 dst-m= ac to be the mac address of e80::225:90ff:fed3:bfb4??? how do you know that fe80::225:90ff:fed3:bfb4 supports ipv4 forwarding on the receiving interface (and if it does, why didn't it advertise itself as an IPv4 router on that interface)? > > This is somehow possible now by exploiting static arp entries and > "unused" IPv4 addresses for nexthop, but is far from ideal. > > Hope someone will be able to provide some insight on what is planned > in this area, and weather this direct functionality will ever make it > into the kernel. >