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From: kwe@bu-it.bu.edu (Kent England)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Multiple IP networks on one Ethernet interface
Message-ID: <58605@bu.edu.bu.edu>
Date: 11 Jun 90 17:14:38 GMT
References: <90Jun6.101602edt.57781@ugw.utcs.utoronto.ca>
Sender: news@bu.edu.bu.edu
Reply-To: kwe@bu-it.bu.edu (Kent England)
Organization: Boston University
Lines: 31

In article <90Jun6.101602edt.57781@ugw.utcs.utoronto.ca>,
FILLMORE@EMRCAN.BITNET writes:
> ... I would like to know if any of
> the commercially-available TCP/IP packages have the capability of either:
> 
>      1)  sending and receiving IP packets for more than one subnetwork
>          over the same Ethernet interface.
> 
>  or: 2)  routing packets between two or more subnetworks over the
>          same Ethernet interface.
> 
> We have several spare Ethernet bridges but only one router - a Cisco.

	Multiple subnets on a single interface is a feature of the latest
cisco software.  Look in the manual update section, not the manual.  It
is the primary/secondary designation of the ip-address of a given
interface.
 ...
> We also run WIN/TCP for VAX/VMS and Control Data's TCP/IP product.  Can
> either of these be configured for multiple subnets on one interface?
> 
	Rather than configure each host to be a member of each subnet on 
the given wire, I would recommend setting the subnet mask such that each
host on the wire would ARP for all directly connected hosts.

	You could simply set the subnetmask to the netmask (ie, no subnet)
on each host on the LAN and let the router proxy for any nonlocal destinations.
This seems to me to be a cleaner approach than creating multiple addresses 
for each host on the shared subnets.

	This will not work for multiple networks, only subnets.