Question abt arp in 5.1-RELEASE

Lowell Gilbert freebsd-questions-local at
Fri Nov 21 05:56:28 PST 2003

"Ilya V. Serov" <iliah at> writes:

>     I've got a curious thing with FBS 5.1-RELEASE, concerning arp
> requests/reply. I have a LAN, connected to Internet through CISCO
> router. Recently I had to move one ip address inside my LAN from a 4.8
> box to a 5.1 box without a reboot (ifconfig ...). After this I had
> discovered that CISCO continue sending packets to old MAC address (to
> 4.8). After an investigation of the problem I discovered, thet CISCO
> had not "forgotten" the old MAC. If  ip is being moved from 4.8 box to
> 4.8 box this effect fanishes.
>     Did anyone get similar problems? Is it a feature or a bug in 5.1,
> or I don't understand something?

It *should* be normal behaviour.  The other devices on the Ethernet
shouldn't update their ARP listings until the box sends out some kind
of broadcast packet.  If it doesn't do so, the other devices will time
out their ARP mappings in 5 minutes.

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