Newsgroups: comp.protocols.tcp-ip Path: utzoo!henry From: henry@utzoo.uucp (Henry Spencer) Subject: Re: ToasterNet (was Re: Running out of Internet addresses?) Message-ID: <1988Dec2.191340.8180@utzoo.uucp> Organization: U of Toronto Zoology References: <8811281821.AA00300@bel.isi.edu> <207@logicon.arpa> <1010@asylum.sf.ca.us> <729@lts.UUCP> Date: Fri, 2 Dec 88 19:13:40 GMT In article <729@lts.UUCP> amanda@lts.UUCP (Amanda Walker) writes: >... He described Ethernet addresses as having >been "designed to be intergalactically unique." > >The biggest problem, I think, is that 32 bits (or 48, or whatever) is >certainly big enough to serve as a *physical* addressing scheme, but >we keep chopping up addresses so that we can have a *logical* addressing >scheme... Another thing that Xerox arguably did right with Ethernet: the 48-bit addresses are *not* chopped up this way. They are in fact divvied up by manufacturer, but manufacturers are supposed to use their part of the space completely before getting another one. The Xerox notion is that the 48-bit address provides a unique identifier for the destination, and any information needed to efficiently locate said destination should be supplied separately. (As I recall, XNS adds a 16-bit network number as a routing hint.) The paper some years ago in SIGCOMM [grr, I just realized I don't have an exact reference handy] on the design of Ethernet addressing should be required reading for anyone thinking about this. -- SunOSish, adj: requiring | Henry Spencer at U of Toronto Zoology 32-bit bug numbers. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu