Subject: Re: arp.
To: Curt Sampson <>
From: Doug Russell <>
List: tech-net
Date: 04/07/1999 00:02:24
On Tue, 6 Apr 1999, Curt Sampson wrote:

> In other words, you have split your network into two subnets, but
> because you have no control over the `main router' above, you cannot
> inform it of the new subnet mask, so it believes that all the hosts
> on the subnet are local.
> This is not hard to solve; you just turn on routing in the sub-router
> box and enable proxy-arp. This will cause the subrouter box, when
> it receives an arp request for the 128/25 subnet on the 0/25
> interface, to reply to that ARP with its own address. The host that
> requested the arp then sends all packets to the sub-router, and
> normal routing gets it to its destination.

Yes...  I use set   sysctl -w   on FreeBSD
to allow my 'main router' to pick up all incoming packets coming in from a
RADSL connection.  The Prardyne 5446 RTU has no internal routing
capabilities, so I have to have my router box listen and distribute
accordingly.  The proxyall saves you the trouble of constantly trying to
keep your manual MAC address table up to date.

               3Com RAS 1500---ISDN Dialins (Dialin56s/28)
            ed0  |fxp0
gatenet/30	 |ppp0
                 |tun0     fxp0
                            |      |      |      |
                           ppp0   ppp1   ppp2   ppp3

Later......						<Doug>