From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [Patch iproute2] vxlan: use 8472 as default dst port Date: Wed, 15 May 2013 10:43:08 -0700 Message-ID: <20130515104308.5de3e852@nehalam.linuxnetplumber.net> References: <1368616270-5775-1-git-send-email-amwang@redhat.com> <20130515095322.275c9b2f@nehalam.linuxnetplumber.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Cong Wang , netdev@vger.kernel.org, netdev-owner@vger.kernel.org To: David Stevens Return-path: Received: from mail-pd0-f182.google.com ([209.85.192.182]:60898 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759815Ab3EORnM (ORCPT ); Wed, 15 May 2013 13:43:12 -0400 Received: by mail-pd0-f182.google.com with SMTP id 3so1562913pdj.41 for ; Wed, 15 May 2013 10:43:11 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 15 May 2013 13:19:43 -0400 David Stevens wrote: > netdev-owner@vger.kernel.org wrote on 05/15/2013 12:53:22 PM: > > > From: Stephen Hemminger > > > No. I want all users to get the IANA assigned port unless they > specifically > > override it. For compatibility kernel can't change to the IANA value > > but user space needs to nudge users in the correct direction. > > It's more than a nudge -- it doesn't interoperate with itself. > > 1) The kernel binds to 8472 on module load. > 2) After it's bound, iproute2 "changes" the port to 4789, but > the kernel binding is still 8742 for listening. All destinations > use > the new port, but all bindings use the old port. > > So, boot two systems without specifying a port and they can't > talk to each other. They both listen on 8742 and they both send to > 4789. > > This clearly is worse than changing the kernel default port to 4789, but > what's the point of having a kernel default if a user-level program > overrides > it even when the user did not specify a port, and only for half of it (the > sender side)? > > You could make a port change close and rebind, but that's little different > than changing the default in the kernel, if "ip" does it without a port > specification. > +-DLS > I want all new users to get the IANA port without asking. Old users with existing nets have to force the port to the one they were using.