Path: utzoo!attcan!uunet!ogicse!decwrl!ucbvax!A.ISI.EDU!PADLIPSKY
From: PADLIPSKY@A.ISI.EDU (Michael Padlipsky)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  Hosts whose IP numbers end in 0...
Message-ID: <12619306165.20.PADLIPSKY@A.ISI.EDU>
Date: 4 Sep 90 19:59:07 GMT
References: <9008311641.AA02779@braden.isi.edu>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 35

Bob, Jon, et al.--

In the spirit of "Sometimes it's necessary to make sure everybody means the
same thing even by 'NO-OP'", I suspect it's past time for me to observe that
the problem with the Subject "thread" is that some of the discussants seem
to be making rather different unstated assumptions about "filtering" than
others are.

I THINK the original question had to do with what we might call "outgoing
filtering", in the sense of rejection of datagrams by gateways other than
the gateway which is connected to the/a communications subnetwork (NOT "subnet"
in the current jargon sense of the term) to which the destination Host is
attached, which is the only gateway that could "know" whether the proferred
address would lead to a broadcast.  Yet several of the responses SEEM to be
taking the point of view of just that "terminal" gateway and holding that
of course it's entitled to "filter".  My own impression is that it's precisely
this latter, "incoming filtering", case in which "judgement" might/can/should
be exercised by a gateway, and only this latter, incoming filtering case.
But irrespective of whether that's the "correct" view, I do think that the
thread will remain tangled until and unless we start explicitly distinguishing
between "outgoing" and "incoming" "filtering"--the failure to do which 
EXPLICITLY I did mentally note, and regret not commenting upon, when the
message Jon subsequently endorsed went by, b/t/w, thinking I'd probably just
skimmed over it too quickly and assuming the issue would eventually be
resolved without my having to make a religious (= Semantic Puritanism)
issue of it.

However, now that we've got the co-authors of the Requirements RFC in
apparent disagreement, it does seem desirable to confirm that they aren't
just re-enacting the old baddie about the neighbors who could never agree
because they were arguing from different premises....

Semantically Puritanical cheers,
           map
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