Introduced 1984 : IEEE 802.5

Token ring - invented by IBM.
  Proprietary and somewhat more complex and twice as expensive.

  Physically arranged as a ring. With right connection, some flexibility.

  Behaves almost like a ring of point to point connections.

  4 MBits/sec, single token. (later 16MBits/sec., multiple tokens)

  Each machine has a single card.
    Card designed with dual ports to allow traffic to come in from one 
    direction and out the other.

    If token/packet not addressed to node, simply repeated. 
      This also guarenteed the quality of the token/packet.