The Free On-line Dictionary of Computing (30 December 2018):

token ring

   A computer local area network arbitration scheme in which
   conflicts in the transmission of messages are avoided by the
   granting of "tokens" which give permission to send.  A station
   keeps the token while transmitting a message, if it has a
   message to transmit, and then passes it on to the next
   station.

   Often, "Token Ring" is used to refer to the IEEE 802.5 token
   ring standard, which is the most common type of token ring.

   Usenet newsgroup: news:comp.dcom.lans.token-ring.