Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun-barr!decwrl!mogul
From: mogul@decwrl.dec.com (Jeffrey Mogul)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  Using the 4.2 broadcast addr with 4.3 systems
Message-ID: <171@jove.dec.com>
Date: 28 Aug 89 21:09:19 GMT
References: <8908281554.AA25419@ucbvax.Berkeley.EDU>
Organization: DEC Western Research
Lines: 22

dcrocker@AHWAHNEE.STANFORD.EDU (Dave Crocker) writes:
    Let me try out a potential Universal Truth, and see if anyone objects:
    
    If you have 4.2-based TCP implementations, then you MUST use
    zero-based IP broadcasting, with zeroes in the host portion of the
    IP address.

Ok, I'll bite.  How about:
    If you have 4.2-based TCP implementations, then you MUST
    fix them, or stop trying to support broadcast applications.

Since there isn't much point to broadcasting in 4.2BSD except for
routed (install a default route to a neighboring gateway) and rwhod
(who needs it, anyway?), I wouldn't worry about it.  The latest
draft of the Host Requirements document is a little slippery ...
it says that hosts MUST recognize legally-addressed broacasts
(all-ones style) but then it mentions that a host MAY be allowed to
send all-zeros style broadcasts.  This seems contradictory, but it
probably reflects the most Universal Truth of all: do what you have
to do, if you can't do what's right.

-Jeff