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Path: utzoo!watmath!clyde!burl!ulysses!ucbvax!tcp-ip
From: tcp-ip@ucbvax.ARPA
Newsgroups: fa.tcp-ip
Subject: Re:  tcp/ip on hyperchannel
Message-ID: <8622@ucbvax.ARPA>
Date: Fri, 28-Jun-85 20:22:48 EDT
Article-I.D.: ucbvax.8622
Posted: Fri Jun 28 20:22:48 1985
Date-Received: Sat, 29-Jun-85 03:49:51 EDT
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Organization: University of California at Berkeley
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From: ihnp4!ihu1e!jee@BERKELEY

The protocol on the Hyperchannel is best described as a CSMA/CP where
CP is collision prevention. This roughly equates to a p-persistenc CSMA
except it is prioritized.

What all this means is that it is CSMA when it is planning to transmit.
All adapters  recognize when a transmission is happening. If they have
to transmit each waits a different time (the backoff algorithm) which
is preselected (the priority). It is true that prior to transmission
of the actually date there is a control information exchange with the
destination adapter.  It is a simple way of making sure the channel is
clear prior to transmission (i.e collision occurring after transmission
begins) and the time is only equal to the round trip time.  This control
information allowys them to do transmit very large packets (much more
than 4kbytes).

In fact their protocol is similar to the proposed ANS X3T9.5 proposed
standard for high speed local networks.

I would suggest you contact Network
Systems Corporation in Minneapolis, Minnesota directly for some
introductory information which goes into much more detail.