Default route doesn't change to wireless device (ath0)

Jon Dama jd at ugcs.caltech.edu
Fri Sep 9 14:49:51 PDT 2005



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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