Date: Mon, 19 Aug 2013 17:58:47 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Joe Holden <lists@rewt.org.uk> Cc: freebsd-net@freebsd.org Subject: Re: Updating route MTU when interface changes Message-ID: <20130820005847.GY94127@funkthat.com> In-Reply-To: <520B8694.1050407@rewt.org.uk> References: <520B8694.1050407@rewt.org.uk>
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Joe Holden wrote this message on Wed, Aug 14, 2013 at 14:31 +0100:
> I noticed this some years ago but I just checked and its still there -
> when the mtu of an interface is changed, any routes (eg connected route)
> using that interface aren't updated until the interface is shut/unshut -
> is this by design or is it an oversight? Having to down/up remote
> machine interfaces that are potentially forwarding traffic just to
> change the mtu seems silly.
FreeBSD used to have code that would automaticly increase a route's MTU
to the largest that the interface provided... This is an issue if you
want to support a mixed MTU lan... You can no longer administrivally
restirct the size of packets being sent out...
The other option is to simply delete all the host routes for that
interface and change the net route, and things will be what you expect..
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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