Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!oscsunb!kannan From: kannan@osc.edu (Kannan Varadhan) Newsgroups: comp.protocols.tcp-ip Subject: Re: Hosts whose IP numbers end in 0........ Message-ID: <854@manhandler.osc.edu> Date: 27 Aug 90 19:38:51 GMT References: <7842@gollum.twg.com> <1990Aug25.220042.29632@ircam.ircam.fr> <1990Aug26.171641.14037@cs.umn.edu> <63256@bu.edu.bu.edu> Organization: Ohio Supercomputer Center & OARNet, Columbus, OH Lines: 50 Thus spake kwe@bu-it.bu.edu (Kent England) > 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 , , or 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: > > [...7 special cases...] > > I therefore conclude that a host part of zero is never a legal source address. The gentleman said earlier: : From: mf@ircam.ircam.fr (Michel Fingerhut) : Date: 25 Aug 90 22:00:42 GMT : Organization: IRCAM, Paris (France) : : Our LAN is a class B network, 129.102.0.0, and I had the unfortunate idea to : choose *legal* IP numbers for some of our main hosts of the form 129.102.nn.0, : (nn != 0). It's legal for a machine, since the HOST part, nn.0, is definitely : NOT zero. Given that he has not explicitly mentioned his subnet masks, and that he mentions that his "HOST part" is "nn.0", his becomes 129.102, and his becomes nn.0. On the face of it, therefore, I'd be inclined to say, he has a point. >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. :-) Aye, that it is :-) Kannan PS: I'd actually be more inclined to think that he probably subnetted his router configurations by mistake, and should very, very carefully check them up before barking up the rouing tree. -- Kannan Varadhan, Internet Engineer, OARNet Ohio Supercomputer Center, Columbus, OH 43212 +1 (614) 292-4137 email: kannan@oar.net | osu-cis!malgudi.oar.net!kannan