From ray@isc.org Fri Nov 18 11:17:15 2016 MIME-Version: 1.0 X-Spam-Status: No, score=-4.3 required=5.0 tests=ALL_TRUSTED,BAYES_00, RP_MATCHES_RCVD autolearn=ham autolearn_force=no version=3.4.0 content-type: text/plain; charset="utf-8" Message-ID: Received: from mx.ams1.isc.org (mx.ams1.isc.org [199.6.1.65]) by bugs.isc.org (Postfix) with ESMTP id 4A9A771B5A8 for ; Fri, 18 Nov 2016 11:17:15 +0000 (UTC) Received: from zmx1.isc.org (zmx1.isc.org [149.20.0.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx.ams1.isc.org (Postfix) with ESMTPS id 1C7441FCAC5 for ; Fri, 18 Nov 2016 11:17:13 +0000 (UTC) Received: from zmx1.isc.org (localhost [127.0.0.1]) by zmx1.isc.org (Postfix) with ESMTPS id 02D0A16004F for ; Fri, 18 Nov 2016 11:17:12 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by zmx1.isc.org (Postfix) with ESMTP id 8ED72160072 for ; Fri, 18 Nov 2016 11:17:11 +0000 (UTC) Received: from zmx1.isc.org ([127.0.0.1]) by localhost (zmx1.isc.org [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id WTtRcXLLVvve for ; Fri, 18 Nov 2016 11:17:11 +0000 (UTC) Received: from rays-mbp.local (unknown [106.255.97.132]) by zmx1.isc.org (Postfix) with ESMTPSA id 2347316004F for ; Fri, 18 Nov 2016 11:17:10 +0000 (UTC) Delivered-To: bind9-bugs@bugs.isc.org Subject: TCP segment handling issue? User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 Return-Path: X-Original-To: bind9-bugs@bugs.isc.org Date: Fri, 18 Nov 2016 20:17:07 +0900 X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on mx.ams1.isc.org To: bind9-bugs@isc.org Content-Transfer-Encoding: 7bit From: "Ray Bellis" X-RT-Original-Encoding: utf-8 X-RT-Interface: Email Content-Length: 499 Via kato@wide.ac.jp: bind-9.11.0-p1 seems to me that it applys TCP_MAXSEG to 1220byte even in IPv4, resulting TCP transmission a little bit less efficient. At around line 3698 of lib/isc/unix/socket.c, the code should be executed only if protocol family is AF_INET6: if (NEWCONNSOCK(dev)->pf == AF_INET6) { use_min_mtu(NEWCONNSOCK(dev)); set_tcp_maxseg(NEWCONNSOCK(dev), 1280 - 20 - 40); } This relates to the survey done by Geoff Huston and reported on his blog earlier this week.