From owner-svn-src-head@FreeBSD.ORG Thu Mar 11 23:30:26 2010 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 90A1E1065673; Thu, 11 Mar 2010 23:30:26 +0000 (UTC) (envelope-from tomelite82@gmail.com) Received: from mail-qy0-f175.google.com (mail-qy0-f175.google.com [209.85.221.175]) by mx1.freebsd.org (Postfix) with ESMTP id 0DE568FC12; Thu, 11 Mar 2010 23:30:25 +0000 (UTC) Received: by qyk5 with SMTP id 5so628615qyk.13 for ; Thu, 11 Mar 2010 15:30:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to:cc :content-type:content-transfer-encoding; bh=J4U23D4DwntTbUtv5MFMkgf5i8JAsqNEghE2flH5Xdg=; b=uZJxEZ9BVFwaYqy8iWFZRh40oFezwkx0ngwJ+RO2Cg9ISM0rRgrTnv5M1BQOO1Zyu0 KcfTjHGy+LJhS+mpD3KKjLX15T+oQN2UUVuMJtH0g98/cEhzAiZhPQRb3hVWKodQcyOg VdOKitRGdQ5A2p9lhxJC4ZosL00sOBPUOjFFM= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=OcGTlxSdPu6GI7IHc85kMafzXXO5Bl+uC014vtTStcsobV0Ubus4iYx03EjrV0dcs1 GWk5xcO6klvJFTcHUtopqLWezi7GwI9sNNIabeKX+S7P29IblzzA/gkZKaTZCezU+PrZ qSp/Zcz39NMa9FgFxNoUWctJvwekH9OrxxgiM= MIME-Version: 1.0 Sender: tomelite82@gmail.com Received: by 10.220.123.207 with SMTP id q15mr366017vcr.186.1268350225105; Thu, 11 Mar 2010 15:30:25 -0800 (PST) In-Reply-To: References: <201003111756.o2BHukJu042449@svn.freebsd.org> Date: Thu, 11 Mar 2010 15:30:25 -0800 X-Google-Sender-Auth: f1a9a28a70e3afff Message-ID: <9ace436c1003111530s3bd0de9cq451671909fb6aa64@mail.gmail.com> From: Qing Li To: Robert Watson Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r205024 - head/sys/net X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Mar 2010 23:30:26 -0000 > > A couple of questions: > > (1) It used to be the case that quite a few interface drivers and types > didn't have a notion of "link up" -- especially older ethernet devices. = =A0Do > those all have the same problem? =A0It was probably a design oversight th= at >=A0devices don't declare an explicit capability for "can report link state= ". > What you raised is definitely a possibility and these fixes take the similar approach. I am going to try and go through each of these drivers in /sys/dev/ and converting them, very soon. > > (2) While loopback interfaces don't really have a link state, they can be >=A0administratively down -- should/do you check that as well as link state= ? > And more generally, even if link is up, administratively down should be >=A0obeyed? > For loopback interfaces, althgouth administrative these can be taken down= , I personally cannot think one practical usage case where ECMP across loopback interfaces would be interesting or usefaul. So I can think of very little reason to be concerned in the loopback case. > > Finally, it would be neat if there were a way to have information beyond > link state influence the choice to balance to a particular route/interfac= e. > =A0For example, imagine if I have a router with ECMP, and on the other si= de on > a single ethernet segment, I have two DSL modems. =A0The ethernet link wi= ll > remain up, but I may (via out-of-band mechanisms, such as SNMP or an acti= ve > probe) be able to tell that one of the DSL lines is down. =A0Is there a w= ay to > push that information into the kernel currently without deleting the rout= es, > and instead say "yeah, but for ECMP purposes this is 'down'"? > The above really falls into policy based routing. And policy based routing infrastrucutre is something I have already been working on but cannot yet push back into -current. In fact Julian and I had a conversation about this topic during the FIBs implementation time in late 2008. This infrastructure enhancement is definitely coming but I cannot yet prv= oide a timeline for merge back. It's mostly a time issue. Let me know if I have answered these questions to your satisfaction. -- Qing