Ref: 09930016
Title: IBM Token Ring Network Operation
date: 7/27/90

Copyright 3Com Corporation, 1991.  All rights reserved.

The IBM Token Ring network is a star-wired ring that, when used with
IBM Cabling System Type 3 Specified Media, allows you to connect up to
72 attaching devices (printers, processors, and controllers) per ring
through specially designed adapters installed in the attaching devices.

   NOTE:  Type 3 Specified Media is telephone twisted-pair cabling
   recommended for use with the IBM Token Ring network.  See technical
   article 9930006 for the media specification.

The attaching device interfaces with the adapter to use the ring for
sending and receiving data.  The attaching device tells the adapter that it
wants to send a message to another attaching device.  The adapter places
the message, the sender's address, and the recipient's address on a token
circulating around the ring.  The token then becomes a frame.

The recipient's address on the frame tells each adapter on the
ring whether or not the message contained on the frame is
intended for it.  If it is, the adapter passes the information on
the frame to its attaching device and indicates on the frame that
the message has been received.  Then the frame continues around
the ring until it returns to the adapter that put the information
on it.  After the adapter checks the information on the frame to
assure that it has not been corrupted, it releases a new token on
the ring.

The IBM Token Ring network is a baseband system that permits only
one token or frame on the ring at a time.  Messages are
transmitted and received at a rate of 4 or 16 megabits per
second.  All normal network operations are performed without user
intervention, once the message has been directed to the adapter.
The operator of the attaching device does not have to be aware of
routing and protocol procedures.

