Date: Thu, 14 Jul 2005 12:14:49 -0700 From: Bakul Shah <bakul@BitBlocks.com> To: Robert Watson <rwatson@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: Problems with OpenBSD dhclient Message-ID: <200507141914.j6EJEneq070016@gate.bitblocks.com> In-Reply-To: Your message of "Thu, 14 Jul 2005 19:27:10 BST." <20050714192403.H35071@fledge.watson.org>
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> > More serious is that I can't roam. When I move between APs, dhclient > > exits and I need to manually re-start it. I lose my SSH sessions. Ugh! > > > > Worse, I occasionally see my association drop momentarily when I am > > simply sitting and typing. Once again, dhclient dies and I must manually > > restart it and then re-establish my SSH and recover anything broken when > > the connection dropped. This is fairly serious! I don't understand what > > causes this, but it is infrequent which makes it hard to catch. > > > > It looks like killing dhclient when the interface drops is not a good > > idea. At very least, it needs to give a little time for re-association > > before dropping the DHCP client. > > I'm experiencing similar or identical problems. When at the British > Library the day before yesterday, slight blips in my association would > result in loss of my IP address, requiring manual restarting of dhclient. > > My normal approach for wireless/etc is to settle on a link -- be it wired > ethernet or 802.11, and run dhclient on it to get things going. When > done, I'll typically kill off dhclient. This worked pretty well with the > old dhclient setup, but not so well with the new one. Because I range > over a variety of network environments, from adhoc 802.11, wired ethernet, > to base station based 802.11, I tend to want to say "do this for now", and > have it stick until I move on. Maybe what I need to change is software > configuration -- i.e., devd to re-launch dhclient. But obviously what I'm > doing now isn't working, and results in a pretty poor user experience > (blips or roaming and suddenly the network is gone). To avoid interface flapping perhaps some hysteresis needs to be introduced in dhclient? If a link up event occurs within N seconds of a link down event, ignore them both! N may need to be tunable. Such hysteresis is _not_ needed for administrative up/down -- when I say `ifconfig ath0 down', I want it down *now*! Devd does need to relaunch dhclient (& wpa_supplicant etc.) on a genuine link up event.
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