From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH net-next v3 0/4] net: ipv6: Improve user experience with multipath routes Date: Mon, 30 Jan 2017 15:56:30 -0800 Message-ID: <20170130155630.787daf0a@xeon-e3> References: <1485559258-4856-1-git-send-email-dsa@cumulusnetworks.com> <588D3EB9.1070107@cumulusnetworks.com> <592be6dc-df0e-6185-ba6f-5acf5d042ae5@cumulusnetworks.com> <588E80DB.3070209@cumulusnetworks.com> <71e661bd-e26d-2629-06bb-888f6a09b06d@cumulusnetworks.com> <588EA2E8.2040302@cumulusnetworks.com> <5be4a78e-64b8-abc4-4015-6751a2bab12b@cumulusnetworks.com> <588F607D.2050600@cumulusnetworks.com> <588F89E5.9060503@cumulusnetworks.com> <20170130131600.00c21eb3@xeon-e3> <7a363b93-bf14-9a13-d154-42a26ac06a06@cumulusnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Roopa Prabhu , netdev@vger.kernel.org, nicolas.dichtel@6wind.com To: David Ahern Return-path: Received: from mail-pf0-f171.google.com ([209.85.192.171]:33955 "EHLO mail-pf0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751134AbdA3X4i (ORCPT ); Mon, 30 Jan 2017 18:56:38 -0500 Received: by mail-pf0-f171.google.com with SMTP id e4so95045526pfg.1 for ; Mon, 30 Jan 2017 15:56:38 -0800 (PST) In-Reply-To: <7a363b93-bf14-9a13-d154-42a26ac06a06@cumulusnetworks.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 30 Jan 2017 16:53:44 -0700 David Ahern wrote: > On 1/30/17 2:16 PM, Stephen Hemminger wrote: > > My fear is that routing daemons already adapt to the funny semantics of multi-path routing in IPv4 vs IPv6 > > and therefore any change in semantics or flags risks breaking existing user space. > > That is a possibility, but so far the 2 open source code bases I know of have problems with IPv6 mpath. Breaking closed source is not acceptable either. > > As I mentioned quagga does not work with IPv6 multipath as is today. > > I just looked at bird. IPv6 mpath support was added in Sept. 2016. It specifically hard codes not accepting RTA_MULTIPATH for IPv6 which I think is an odd choice and clearly coding to quirks as opposed to rtnetlink design. Having never looked at bird code I was able to get it working in < 1 hour. I will contact the patch author about that limitation. That said, the bird implementation needs work when you look at the add/delete/replace/append permutations, so the current code has its problems as well. Also what if quagga was fixed but had to work with existing enterprise distros?