Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!batcomputer!cornell!uw-beaver!zephyr.ens.tek.com!tektronix!percy!m2xenix!quagga!undeed!barrett From: barrett@Daisy.EE.UND.AC.ZA (Alan P. Barrett) Newsgroups: comp.protocols.tcp-ip Subject: Re: How to set up subnets where logical subnet != physical subnet Keywords: subnet routing Message-ID: <1991Apr15.102332.12974@Daisy.EE.UND.AC.ZA> Date: 15 Apr 91 10:23:32 GMT References: <1991Apr10.063716.9725@cs.columbia.edu> Organization: Univ. Natal, Durban, S. Africa Lines: 29 In article <1991Apr10.063716.9725@cs.columbia.edu>, ji@liberty.columbia.edu (John Ioannidis) writes: > >router to present miltiple IP addresses without plugging in extra > >network cards. This would be an alternate solution that would not > > CISCOs can do that. On BSD-derived Unixes, [you probably can't do it]. PC-Route can do that, if you get the declare.inc file right, which is not very difficult. However, the documentation doesn't even mention that this is possible, much less explain how to do it. OK, now a question for the standards folk. Section 2.3 of RFC791 (the IP standard) has this to say: rfc791> Care must be taken in mapping internet addresses to local net rfc791> addresses; a single physical host must be able to act as if it were ^^^^ rfc791> several distinct hosts to the extent of using several distinct rfc791> internet addresses. Some hosts will also have several physical rfc791> interfaces (multi-homing). If the word "must" here really means MUST in the Host-Requirements sense, then shouldn't all IP implementations allow a host to present multiple IP addresses without having multiple interfaces? --apb Alan Barrett, Dept. of Electronic Eng., Univ. of Natal, Durban, South Africa Internet: barrett@ee.und.ac.za UUCP: m2xenix!quagga!undeed!barrett