From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from tuna.sandelman.ca (unknown [IPv6:2607:f0b0:f:3:216:3eff:fe7c:d1f3]) by huchra.bufferbloat.net (Postfix) with ESMTP id D56F321F14B; Mon, 26 Nov 2012 13:28:21 -0800 (PST) Received: from obiwan.sandelman.ca (unknown [IPv6:2607:f0b0:f:2::247]) by tuna.sandelman.ca (Postfix) with ESMTP id 752632016D; Mon, 26 Nov 2012 16:29:59 -0500 (EST) Received: by obiwan.sandelman.ca (Postfix, from userid 179) id CF1BF63A8E; Mon, 26 Nov 2012 16:27:47 -0500 (EST) Received: from obiwan.sandelman.ca (localhost [127.0.0.1]) by obiwan.sandelman.ca (Postfix) with ESMTP id C154E63A8C; Mon, 26 Nov 2012 16:27:47 -0500 (EST) From: Michael Richardson To: dpreed@reed.com In-Reply-To: <1353959938.625616504@apps.rackspace.com> References: <20121125232034.GF24680@merlins.org> <31933.1353939756@obiwan.sandelman.ca> <1353942251.571510886@apps.rackspace.com> <13866.1353944313@obiwan.sandelman.ca> <1353947863.437620265@apps.rackspace.com> <9615.1353953507@obiwan.sandelman.ca> <1353959938.625616504@apps.rackspace.com> X-Mailer: MH-E 8.3; nmh 1.3-dev; XEmacs 21.4 (patch 22) X-Face: $\n1pF)h^`}$H>Hk{L"x@)JS7<%Az}5RyS@k9X%29-lHB$Ti.V>2bi.~ehC0; <'$9xN5Ub# z!G,p`nR&p7Fz@^UXIn156S8.~^@MJ*mMsD7=QFeq%AL4m Sender: mcr@obiwan.sandelman.ca Cc: cerowrt-users@lists.bufferbloat.net, cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] [Cerowrt-users] QOS settings vs speedboost and random bandwidth X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Nov 2012 21:28:23 -0000 >>>>> "dpreed" == dpreed writes: dpreed> It observed the IPv4 headers of *large* TCP/IP datagrams dpreed> going upstream, so that it could construct "no-op" dpreed> "content-free" datagrams that would certainly pass muster dpreed> through all the filters and be routed exactly the same as dpreed> the TCP/IP datagrams that were carrying large flows. It dpreed> would remember only the most recent one. I don't know that you need to be so precise in creating the packet, but I guess the point is not just the ACLs, but also any traffic shapers? dpreed> The TTL expiration causes an ICMP packet to be sent back. dpreed> My code intercepts that packet based on its contents, and dpreed> removes it as "handled" before it gets processed by the dpreed> TCP/IP state machines. This is perhaps the biggest problem with this method... having to remove the magic ICMP so that it does no harm. Without this requirement, it could be done entirely in userspace I think. -- ] He who is tired of Weird Al is tired of life! | firewalls [ ] Michael Richardson, Sandelman Software Works, Ottawa, ON |net architect[ ] mcr@sandelman.ottawa.on.ca http://www.sandelman.ottawa.on.ca/ |device driver[ Kyoto Plus: watch the video then sign the petition.