Date: Tue, 19 Feb 2013 10:51:38 -0800 From: Chuck Swiger <cswiger@mac.com> To: Alex Yong <annonymouse+freebsd@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: Wallclock vs monotonic time in v6 expiry times? Message-ID: <D1912C84-78AF-46B9-9B4B-3871EEC782F9@mac.com> In-Reply-To: <CAJW_4zAszUermNQ0Xmz_G2A1X9Oz-2WhbrRj3UNKtCnDu-obmg@mail.gmail.com> References: <CAJW_4zAszUermNQ0Xmz_G2A1X9Oz-2WhbrRj3UNKtCnDu-obmg@mail.gmail.com>
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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
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