Ken Olsen vs MAP


martillo@ATHENA.MIT.EDU
Tue, 7 Apr 87 21:52:48 EST


Last week Ken Olsen was dumping on MAP/TOP.

Charles Gardner, corporate coordinator of communications standards for
Eastman Kodak Co. and chairman of the MAP/TOP Steering Committee
stated in reply:

"The broadband token bus is needed in the factory, and Olsen doesn't
seem to understand that," he said. "For some control applications,
you need to calculate how long it takes a message to get from one
place to another, and Ethernet can only give a probability."

Excuse me but I thought life was probabilistic even when tokens were
used to solve contention problems. Even if you can calculate the time
to get the token, packets still might get trashed in transmission.
Further if you are using virtual circuit oriented protocols at upper
layers, meerly getting the token does not mean you can transmit, the
relevant window might be closed, because the last time the machine
which could open the window got the token, he was so busy transmitting
to yet another machine that he could not send out necessary ACKs. If
datagrams are being used (which I don't think were part of the MAP
suite when I looked over the spec last year) unreliability makes for
probabalistic calculations.

Do the MAP/TOP people know something which I don't? Or are they just
totally off the wall?

Yaqim Martillo



This archive was generated by hypermail 2.0b3 on Thu Mar 09 2000 - 14:38:07 GMT