From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Miller" Subject: Re: [PATCH] fix tcp_default_win_scale. Date: Tue, 6 Jul 2004 15:49:07 -0700 Sender: linux-net-owner@vger.kernel.org Message-ID: <20040706154907.422a6b73.davem@redhat.com> References: <20040629222751.392f0a82.davem@redhat.com> <20040630152750.2d01ca51@dell_ss3.pdx.osdl.net> <20040630153049.3ca25b76.davem@redhat.com> <20040701133738.301b9e46@dell_ss3.pdx.osdl.net> <20040701140406.62dfbc2a.davem@redhat.com> <20040702013225.GA24707@conectiva.com.br> <20040706093503.GA8147@outpost.ds9a.nl> <20040706114741.1bf98bbe@dell_ss3.pdx.osdl.net> <20040706194034.GA11021@mail.shareable.org> <20040706131235.10b5afa8.davem@redhat.com> <20040706224453.GA6694@outpost.ds9a.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: jamie@shareable.org, shemminger@osdl.org, netdev@oss.sgi.com, linux-net@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: To: bert hubert In-Reply-To: <20040706224453.GA6694@outpost.ds9a.nl> List-Id: netdev.vger.kernel.org On Wed, 7 Jul 2004 00:44:53 +0200 bert hubert wrote: > Not true - the outgoing SYN packet had window scale 7, when it was sent. The > SYN|ACK had window scale 0, when received by the initiating system. > > Also - even if the remote were to assume a 47 byte window size, would it not > be able to send small packets? Or does the window size also include > packet haders? SWS avoidance makes us not send packets. See this quote in an email from John Heffner the other week: ================================ To elaborate on my earlier mail. my hypothesis is that somehow the web server beleives that we sent a winscale of 0. In such a case, when we try to advertise our initial 4*MSS (5840 bytes) of window, with a window scale of 3 we use a value of 730 in the window field. All sender SWS avoidance (RFC1122) tests will fail, most notably 1 (because we already advertised 5840 bytes and 730 < 5840/2) and 3 (because 730 < 1460). With a winscale of 2, we will use a value of 1460 in the window field, so both tests will succeed. ================================