martillo@ATHENA.MIT.EDU.UUCP (04/08/87)
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