Re: IBM TCP.


David C. Plummer (DCP@QUABBIN.SCRC.Symbolics.COM)
Thu, 6 Aug 87 11:05 EDT


    Date: Wed, 5 Aug 87 11:05:49 CDT
    From: sandrock@uxc.cso.uiuc.edu (Mark Sandrock)

    Also, I doubt that if "ACME" vendor tries to market a network that
    conflicts with DECnet that they will have many sales to systems which
    already have DECnet installed. They would most likely (and deservedly)
    soon be a defunct company.

Well, what if it were UniSYS, IBM or GM? Muscle flexing is a very
impolite thing to do anyway, and in open network environments it may
achieve a marketing objective at the expense of thwarting the kinds of
atmospheres that lead to experimentation and creativity.

    Date: Wed, 5 Aug 87 11:18:21 CDT
    From: sandrock@uxc.cso.uiuc.edu (Mark Sandrock)

    Thanks for your message re: DECnet and Ethernet. All of our DECnet
    addresses here at the University of Illinois are assigned by the
    PHYSnet management (whoever that is). We have not yet seen the need
    for multiple areas on this campus. Also, one would expect that DEC
    might anticipate the need and expand the DECnet addressing scheme to
    something reasonable in a future version (Phase V?).

So Hedrick believes (Phase V). Unfortunately, it sounds like they are
going off in another wrong direction. From Hedrick's description, they
will in the future be basing DECnet protocol addresses on the Ethernet
hardware address. Well, what happens if your Ethernet hardware breaks
and you need to replace it? Answer as far as I can tell: you have to
force the new Ethernet address to be the same as the old. What happens
if you recommision the old board on the same net? Another problem: Does
this mean that DECnet Phase V has variable length addresses? What do
they do for networks that have a different number of hardware address
bytes than the Ethernet has? My belief is that protocol addresses are
logically attached to the machine as an entity, that hardware network
addresses are attached to hardware interfaces, and that they should not
be related because of the current problems with (1) DECnet Phase IV and
(2) my understand of Hedrick's description of Phase V. IP, Chaos and
PUP (and probably others I don't know about) do it right.

    Date: Wed, 5 Aug 87 11:24:18 CDT
    From: sandrock@uxc.cso.uiuc.edu (Mark Sandrock)

    It sounds like you are claiming that DEC preempts Ethernet hardware
    addresses which have been officially assigned to other vendors, but
    I have yet to see a specific example of such an address. Is it asking
    to much either to see an example or else have everyone drop this claim?

Sure. There is a Symbolics 3600 at our site that has an Ethernet
hardware address of 08-00-05-03-00-38. The 08-00-05- portion was
assigned to Symbolics by the Ethernet number Czar for use by Symbolics
for its Ethernet interfaces. That is the "official" hardware address of
the interface on that machine. That machine also has a DNA address of
41.69. Because of the way DNA works, the booting procedure for the
machine changes the Ethernet address of the interface to
AA-00-04-00-45-A4. Therefore, DNA has preempted our officially assigned
address.



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