From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [RFC PATCH v3 net-next] net: ipv6: Add a sysctl to make optimistic addresses useful candidates Date: Thu, 23 Oct 2014 17:12:50 +0200 Message-ID: <54491AF2.3070400@6wind.com> References: <1414058399-19695-1-git-send-email-ek@google.com> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: ben@decadent.org.uk, lorenzo@google.com, hannes@stressinduktion.org To: Erik Kline , netdev@vger.kernel.org Return-path: Received: from mail-wg0-f48.google.com ([74.125.82.48]:52648 "EHLO mail-wg0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751469AbaJWPMy (ORCPT ); Thu, 23 Oct 2014 11:12:54 -0400 Received: by mail-wg0-f48.google.com with SMTP id k14so1368644wgh.7 for ; Thu, 23 Oct 2014 08:12:52 -0700 (PDT) In-Reply-To: <1414058399-19695-1-git-send-email-ek@google.com> Sender: netdev-owner@vger.kernel.org List-ID: Le 23/10/2014 11:59, Erik Kline a =C3=A9crit : > Add a sysctl that causes an interface's optimistic addresses > to be considered equivalent to other non-deprecated addresses > for source address selection purposes. Preferred addresses > will still take precedence over optimistic addresses, subject > to other ranking in the source address selection algorithm. > > This is useful where different interfaces are connected to > different networks from different ISPs (e.g., a cell network > and a home wifi network). > > The current behaviour complies with RFC 3484/6724, and it > makes sense if the host has only one interface, or has > multiple interfaces on the same network (same or cooperating > administrative domain(s), but not in the multiple distinct > networks case. > > For example, if a mobile device has an IPv6 address on an LTE > network and then connects to IPv6-enabled wifi, while the wifi > IPv6 address is undergoing DAD, IPv6 connections will try use > the wifi default route with the LTE IPv6 address, and will get > stuck until they time out. > > Also, because optimistic nodes can receive frames, issue > an RTM_NEWADDR as soon as DAD starts. If DAD fails, a separate > RTM_DELADDR is always sent. > > Also: add an entry in ip-sysctl.txt for optimistic_dad. > > Signed-off-by: Erik Kline I agree with the principle of the patch. This option is useful. Thank you, Nicolas