Path: utzoo!utgpu!watserv1!watmath!att!tut.cis.ohio-state.edu!ucbvax!MCIMAIL.COM!0004219666
From: 0004219666@MCIMAIL.COM (Bob Stine)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Getting 4.2BSD to Understand Subnetted Network
Message-ID: <11910106005411.0004219666NB2EM@mcimail.com>
Date: 6 Jan 91 00:54:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 22

>I'm adding 4 VAX 11/750's with *binary-only* 4.2BSD licenses
>(previously running on an XNS network) to a TCP/IP
>network.  The network is a Class B network, with a 255.255.255.0
>netmask.  4.2BSD seems not to understand subnetting, so the
>first such machine on the net sees only itself and a few
>others (386's with an older TCP/IP) which also don't understand
>subnetting.

>What can be done with 4.2BSD to make things work?

If your gateways can do proxy arp, then you could tell the 4.2 hosts that
they are attached to a net with mask 255.255.0.0.  Proxy arp (a.k.a. "the
arp hack," "promiscuous arp") is generally considered to be a kludge, however.

Otherwise, you could install host routes for all the hosts on remote subnets
with which the 4.2 needs to communicate.

Failing these workarounds, I think that you are wedged, although I will be
watching this space with interest.

- Bob Stine
  bstine@MCIMail.com