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Path: utzoo!linus!wivax!decvax!tektronix!ucbcad!ucbvax!sam
From: sam@ucbvax.UUCP
Newsgroups: net.unix-wizards
Subject: Re: 4.1c Ether Addressing Problem - (nf)
Message-ID: <109@ucbvax.UUCP>
Date: Fri, 8-Jul-83 07:40:48 EDT
Article-I.D.: ucbvax.109
Posted: Fri Jul  8 07:40:48 1983
Date-Received: Tue, 12-Jul-83 04:43:46 EDT
References: <1098@zehntel.UUCP>, <1633@allegra.UUCP>
Organization: U. C. Berkeley Computer Science
Lines: 24

Using a static mapping was long ago shown (through practical
experiences) to be infeasible.  A dynamic mapping scheme
is the only way to handle such problems as multi-homed hosts
(suppose a host splits time between network addresses, are
you going to modify your mapping files every 2-3 hours?).
Jim Kulp's algorithm is strongly based on ARP, if it isn't
exactly ARP  (he called me a few months back and described
what he was going to do, it may have changed since then.)
Standards are useful things if created with foresight and
not too heavily influenced by politics.  ARP appears to have
won substantial backing in the Internet world which may 
result in many government locations requiring ARP support in
any network oriented product purchased.  4.2 uses Bill Croft's
ARP code for 10Mb/s Ethernets and some of the people that wrote
interface drivers for other hardware devices have indicated they
are likely to write the necessary code needed to make their
interfaces use ARP.  The bottom line is that if you run 4.2
on a 10Mb/s Ethernet and want another machine to talk to it,
that machine is going to have to support ARP, or you're going
to have to rip apart various pieces of the system.  I suspect
people will find it more attractive to implement ARP.

	Sam Leffler
	(finally starting to find time for things other than 4.2)