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From: 08071TCP@MSU.EDU (Doug Nelson)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: TCP/IP, SNMP, and Bridges
Message-ID: <9105190221.AA10460@ucbvax.Berkeley.EDU>
Date: 18 May 91 22:41:59 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: Doug Nelson <NELSON@msu.edu>
Organization: The Internet
Lines: 19

>   An IP router MUST have different IP addresses on its interfaces. Remember,
>   the purpose of an IP Router is to forward packets between different
>   IP networks and different IP Networks have different IP Network/Subnetwork
>   numbers, therefore the addresses will be different.
>
>I don't think that necessarily follows -- seems to me that KA9Q NOS
>gets by (if you so desire) with one IP address for the whole box, and
>routing done on a per interface basis.  Or am I missing something ?

The question is what address do you use as a gateway address for systems
connected to a given interface.  For serial lines, there is no problem,
since there's only one place to send the data; hence serial lines can
easily live without their own IP address.  For network interfaces, though,
you either need an IP address on the local net, or you have to rely on
proxy ARP to find the gateway.  Now this all assumes *I'm* not missing
something, too.

Doug Nelson
Michigan State University