Date: Fri, 9 Sep 2005 14:49:48 -0700 (PDT) From: Jon Dama <jd@ugcs.caltech.edu> To: Lars Erik Gullerud <lerik@nolink.net> Cc: freebsd-current@freebsd.org Subject: Re: Default route doesn't change to wireless device (ath0) Message-ID: <Pine.LNX.4.53.0509091449220.16645@regurgitate.ugcs.caltech.edu> In-Reply-To: <20050909111927.I31154@electra.nolink.net> References: <20050901225346.0923E16A41F@hub.freebsd.org> <200509021003.39863.incmc@gmx.de> <20050902164957.GA22097@odin.ac.hmc.edu> <200509072128.04819.incmc@gmx.de> <20050907194130.GA2436@odin.ac.hmc.edu> <20050908220217.X64137@electra.nolink.net> <Pine.LNX.4.53.0509081443080.18161@ngwee.ugcs.caltech.edu> <20050909111927.I31154@electra.nolink.net>
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On Fri, 9 Sep 2005, Lars Erik Gullerud wrote: > On Thu, 8 Sep 2005, Jon Dama wrote: > > > > >> Bringing an interface down then back up is usually one of the "try this > >> first" operations when troubleshooting all platforms I normally work on, > >> exactly because it _does_ (normally) clear a lot of state info that you > >> don't want around to confuse you (like the ARP cache and routing table > >> entries). > > > > Yes but surely you'd recognize a difference between a link state change > > and issuing ifconfig ... down > > > > In the latter case, I expect state to be flushed. In the former, I expect > > everything to resume when the link is restored. Imagine having to > > manually reinit your interfaces just because some joker temporary > > unplugged your ethernet cable! > > No, quite the opposite - a link state change is is when you REALLY want > state (particularly ARP) to be flushed. If someone unplugs your ethernet > cable, and the link subsequently returns, you have no way of knowing you > are on the _same network segment_. You may plug out your cable and plug > it into a different network, in which case you do NOT want old ARP > entries to remain. I.e. the new network may use the same IP addressing, > but obviously ARP will point to different macs - in which case you will > get no traffic because your host will not re-ARP IP-addresses for which > it already has a cache entry. ARP cache should _always_ flush on link > state change. > > /leg > To belabor the point, I was talking about the interface configuration. -Jon
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