From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [Xen-devel] [PATCH] xen-netback: Turn off the carrier if the guest is not able to receive Date: Fri, 8 Aug 2014 09:33:56 -0700 Message-ID: <20140808093356.04d7228b@haswell.linuxnetplumber.net> References: <1406749849-4356-1-git-send-email-zoltan.kiss@citrix.com> <1406749849-4356-2-git-send-email-zoltan.kiss@citrix.com> <53DF8C24.6030709@citrix.com> <53DFA30E.2000301@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: David Vrabel , Wei Liu , Ian Campbell , , , To: Zoltan Kiss Return-path: Received: from mail-pd0-f177.google.com ([209.85.192.177]:35680 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756037AbaHHQeC (ORCPT ); Fri, 8 Aug 2014 12:34:02 -0400 Received: by mail-pd0-f177.google.com with SMTP id p10so7248247pdj.22 for ; Fri, 08 Aug 2014 09:33:59 -0700 (PDT) In-Reply-To: <53DFA30E.2000301@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: This idea of bouncing carrier is wrong. If guest is flow blocked you don't want to toggle carrier. That will cause problems because applications that are looking for carrier transistions like routing daemons will be notified. If running a routing daemon this will also lead to link flapping which is very bad and cause lots of other work for peer routing daemons. Carrier is not a suitable flow control mechanism.