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From: MAP@lcs.mit.edu (Michael A. Patton)
Newsgroups: comp.protocols.tcp-ip
Subject: Hosts whose IP numbers end in 0........
Message-ID: <9008272010.AA27718@gaak.LCS.MIT.EDU>
Date: 27 Aug 90 20:10:08 GMT
References: <63256@bu.edu.bu.edu>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
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   Date: 27 Aug 90 16:32:47 GMT
   From: usc!zaphod.mps.ohio-state.edu!rpi!bu.edu!bu-it!kwe@ucsd.edu  (Kent England)

Hi Kent, that's quite a return address you have there and you're only
next door :-).

	   I didn't see anybody cite chapter and verse of the Host
   Requirements RFC and considering the hours spent on that fine
   document, I think it would be a shame not to cite the official
   bible of the Internet (ok, one of the bibles...):

A laudable ambition, but the original poster said he had consulted the
RFCs and not found anything outlawing what he's doing, I don't think
you did either :-).

	[Quotes from RFCs removed]
	   I therefore conclude that a host part of zero is never a
   legal source address.  So I think the petitioner should change the
   addresses on his hosts and not bother his router vendor.

Except that you missed the point of the original poster.  He is not
subnetting and therefore has sixteen bits of host number.  Some of his
hosts are assigned (non-zero) sixteen bit numbers that happen to have
all the last eight bits zero.  According to all the specs this is
legal.  His problem comes in that some gateways (I assume not under
his control) are configured to discard all packets with addresses
having the low eight bits of the address zero.  My reading of this
would be that what he is doing is legal, and the maintainers of the
intervening routers are doing something wrong.  But to follow the "Be
conservative in what you send, liberal in what you accept" policy
would suggest not using such host addresses even though they should be
valid.  That's what we do here.

	    __
  /|  /|  /|  \		Michael A. Patton, Network Manager
 / | / | /_|__/		Laboratory for Computer Science
/  |/  |/  |atton	Massachusetts Institute of Technology

Disclaimer: The opinions expressed above are a figment of the phosphor
on your screen and do not represent the views of MIT, LCS, or MAP. :-)