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From: kwe@bu-it.bu.edu (Kent England)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Hosts whose IP numbers end in 0........
Message-ID: <63256@bu.edu.bu.edu>
Date: 27 Aug 90 16:32:47 GMT
References: <7842@gollum.twg.com> <1990Aug25.220042.29632@ircam.ircam.fr> <1990Aug26.171641.14037@cs.umn.edu>
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Reply-To: kwe@bu-it.bu.edu (Kent England)
Organization: Boston University
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	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...):

-----------------------------
	From RFC 1122 Sec 3.2.1.3  Addressing: RFC-791 Section 3.2;

            "IP addresses are not permitted to have the value 0 or -1 for
            any of the <Host-number>, <Network-number>, or <Subnet-
            number> fields (except in the special cases listed above).
            This implies that each of these fields will be at least two
            bits long."
------------------------------

	The special cases are:

            (a)  { 0, 0 }		[only during initialization]
            (b)  { 0, <Host-number> }	[only during initialization]
            (c)  { -1, -1 }		[limited bcast; never source-addr]
            (d)  { <Network-number>, -1 }	[directed bcast; never source-addr]
            (e)  { <Network-number>, <Subnet-number>, -1 }	[directed
bcast; never source-addr]
            (f)  { <Network-number>, -1, -1 }	[directed bcast; never
source-addr]
            (g)  { 127, <any> }		[loopback addr; never outside a host]


	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.  Isn't the Host Requirements RFC wonderful?  This only
took five minutes
to research and that included checking the commentary in RFC 1127.   :-)

	--Kent