Date: Sat, 9 Mar 2013 19:17:59 +0000 From: Nikolay Denev <ndenev@gmail.com> To: John-Mark Gurney <jmg@funkthat.com> Cc: "Alexander V. Chernikov" <melifaro@freebsd.org>, Andre Oppermann <andre@freebsd.org>, net@freebsd.org Subject: Re: [patch] interface routes Message-ID: <5205A02F-E886-4B7E-8494-1D92F930933B@gmail.com> In-Reply-To: <20130307214205.GD50035@funkthat.com> References: <513834E4.7050203@FreeBSD.org> <51384443.5070209@freebsd.org> <20130307214205.GD50035@funkthat.com>
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On Mar 7, 2013, at 9:42 PM, John-Mark Gurney <jmg@funkthat.com> wrote: > Andre Oppermann wrote this message on Thu, Mar 07, 2013 at 08:39 = +0100: >>> Adding interface address is handled via atomically deleting old = prefix and=20 >>> adding interface one. >>=20 >> This brings up a long standing sore point of our routing code >> which this patch makes more pronounced. When an interface link >> state is down I don't want the route to it to persist but to >> become inactive so another path can be chosen. This the very >> point of running a routing daemon. So on the link-down event >> the installed interface routes should be removed from the routing >> table. The configured addresses though should persist and the >> interface routes re-installed on a link-up event. What's your >> opinion on it? >>=20 >> Other than these points I think your code is fine and can go >> into the tree. >=20 > The issue that I see with this is that if you bump your cable, all > your connections will be dropped, because as soon as they try to send > something, they'll get a no route to host, and this will break the > TCP connection... If we keep the routes when the link goes down, > the packet will be queued or dropped (depending upon ethernet driver), > but the TCP connection will not break... >=20 > --=20 > John-Mark Gurney Voice: +1 415 225 5579 >=20 > "All that I will do, has been done, All that I have, has not." Maybe this can be made a option that can be turned on when needed. What you describe can be very undesirable for a workstation/laptop or a = server, but a router that itself does not have many connections originating or = terminating on it could actually benefit from this. The current state is actually much worse for routers. A link down does = not do anything, and while there may be a alternative route to be installed for example from = OSPF, the interface without link pertains its routes and effectively blackholes all traffic. -- Nikolay
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