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From: michael butler <imb@asstdc.com.au>
Message-Id: <199607140623.QAA00562@walkabout.asstdc.com.au>
Subject: Re: interfaces, routes, etc.
To: archie@whistle.com (Archie Cobbs)
Date: Sun, 14 Jul 1996 16:23:47 +1000 (EST)
Cc: freebsd-hackers@freebsd.org
In-Reply-To: <199607132345.QAA00884@bubba.whistle.com> from Archie Cobbs at "Jul 13, 96 04:45:02 pm"
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>  - When you bring an EtherNet interface up and ping some addresses
>    on that network, you get automatically generated LINK layer routes
>    (ie, arp entries). However, when you bring the interface down
>    these routes do not automatically go away.

I must admit that I was puzzled as to why it was necessary to add MAC
addresses into the route table. I thought they belonged in the ARP table and
nowhere else ..

> One very weird but non-reproducible case involved an ethernet interface
> that had been renumbered several times on the same class c network.

The proper behaviour in changing an IP address, I'm told, is to send out a
packet advising everyone else on the local ether that their ARP table
entries for that particular IP address are now invalid. You can see this by
watching the output of a Cisco when you change its address. It seems that
FreeBSD doesn't do this when (typically) an "ifconfig delete" is done and
other hosts (or routers :-() on the same wire tend to get a little confused,

	michael