Re: Ethernet Security


PADLIPSKY@A.ISI.EDU
23 Feb 1987 13:58:52 EST


Apologies for the delay; my linkage to the List has been temporarily
broken (for about a month now) and it was only through the good
offices of a colleague that I learned my expertise had been
appealed for/to a week or so ago.

By a happy coincidence, the extra time meant that I was able to
confer with Jon Postel on the subtle technophilosophical
questions posed (during the course of a conversation on a far
less intriguing topic), so my response is actually even more
profound than it might have been had it been more timely.
Of course, on the very first point we couldn't quite agree:
I hold that Ethernet physical addresses must be somewhere
between L 1.9 and L 2.1, whereas Jon says 1.7-2.7 (or was it
.7-2.7?). We did agree that they can't be at -1 because
that's where X.75 is, and I'm confident they can't be at 0
since whatever "Sevice Access Points" mean they don't seem to
be any better equipped to deal with zero-indexing than any of us.
(Probably a great deal less so, come to think of it.) I also
believe Jon would agree that if Bob Metcalfe wanted to argue
that in "the real Ethernet/XNS" they could also be viewed as being
at L 3 we'd have to consider such a view favorably, even if
it is rather meta-Physical. (Didn't mean to be overconstraining:
Dave Boggs could also make the argument--even John Schoch, if I
could remember how to spell his name.)

The even harder problem as to what layer university administrators'
phobias belong in did get a joint resolution, however: 68i.
(The analysis was too involved and esoteric to do justice to in
this medium, unfortunately.)

Thanks for asking; it's always a pleasure to be of service.
(Better CC: me directly for the time being if there's anything
else you want to know: the linkage is still flakey and I won't
even be pretending to glance at all msgs for some time [if ever].)

glossabuccal cheers, map
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