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From: robel2@mythos.ucs.indiana.edu (Allen Robel)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: multiple nets on one interface
Message-ID: <33427@boulder.Colorado.EDU>
Date: 19 Mar 91 17:02:59 GMT
Sender: daemon@boulder.Colorado.EDU
Lines: 25

>same cable). It works for us. Since the netmask is class B, different
>net numbers on the same interface just speak directly to each other
>without going through the router. The router is smart enough to know which
>subnets it needs to proxy arp for on each interface (i.e. every subnet

This is not my understanding of how proxy arp works.  The
cisco manual explains in the section "Address Resolution using
"Proxy Arp." (p. 5-9 of the Dec, 17th edition) that the cisco
gives its *own* hardware address in the arp reply.  The host
that sent the request then uses the cisco's hardware address
to get to the destination it enquired about. My assumption is that 

this is the case for multiple subnets on the same interface as well.

Its easy enough to verify (or discount) this with an analyser so
I'll do just that and write back with the results...

regards,

Allen Robel                        robel2@mythos.ucs.indiana.edu 

University Computing Services      ROBELR@IUJADE.BITNET 

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