From owner-freebsd-net@FreeBSD.ORG Tue Feb 19 19:51:45 2013 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 742381F3 for ; Tue, 19 Feb 2013 19:51:45 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from nk11p00mm-asmtp004.mac.com (nk11p00mm-asmtp004.mac.com [17.158.161.3]) by mx1.freebsd.org (Postfix) with ESMTP id 5A00C28C for ; Tue, 19 Feb 2013 19:51:45 +0000 (UTC) Received: from cswiger1.apple.com ([17.209.4.71]) by nk11p00mm-asmtp004.mac.com (Oracle Communications Messaging Server 7u4-26.01(7.0.4.26.0) 64bit (built Jul 13 2012)) with ESMTPSA id <0MIH008BNDQ21T20@nk11p00mm-asmtp004.mac.com> for freebsd-net@freebsd.org; Tue, 19 Feb 2013 18:51:39 +0000 (GMT) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.9.8327,1.0.431,0.0.0000 definitions=2013-02-19_03:2013-02-19,2013-02-18,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 ipscore=0 suspectscore=0 phishscore=0 bulkscore=0 adultscore=5 classifier=spam adjust=0 reason=mlx scancount=1 engine=6.0.2-1203120001 definitions=main-1302190172 Subject: Re: Wallclock vs monotonic time in v6 expiry times? MIME-version: 1.0 (Apple Message framework v1085) Content-type: text/plain; charset=us-ascii From: Chuck Swiger In-reply-to: Date: Tue, 19 Feb 2013 10:51:38 -0800 Content-transfer-encoding: quoted-printable Message-id: References: To: Alex Yong X-Mailer: Apple Mail (2.1085) Cc: freebsd-net@freebsd.org X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Feb 2013 19:51:45 -0000 Hi-- On Feb 19, 2013, at 10:42 AM, Alex Yong wrote: > I've been looking around in the IPv6 code recently and I noticed that > time_second seems to be the clock of choice for calculating expiry = times > for prefixes, routers and addresses. Is there any specific reason it = uses > wall clock time and not time_uptime as this makes more sense to me? Sure. Sequence #s, retry timers, etc do better if based off of wall = clock time than if based off of uptime because realtime persists in moving forward = but uptime gets reset if the host crashes/reboots. RFC-793 discusses "Quiet Time" concept for TCP, but it applies = elsewhere. Regards, --=20 -Chuck