Token Ring
Token Ring is a networking protocol for Local area networks. It uses token passing at the data link layer. The token has two states, either it is free, or it is taken, and data follows. When a computer has a message to send, it appends the message to the token, and sets the token state to taken. Each workstation along the ring sees the message. If the workstation was the recipient of the message, it sends a new empty token, otherwise it passes the token along. Since the only way to send data is to wait for an empty token, there will be no collisions. Token ring is the network that has fair access for all its connected workstations or host.
Token Ring was mainly used by IBM in the 1970s to 1990s, today, Ethernet has replaced it in many applications.
Token Ring Media
Token Ring LAN Logical Network Layout with three hosts connected to a Multi-station Access Unit (MAU). Ring in/out ports are not shown for simplicity.
Token Ring network: operation of an MAU explained
IBM hermaphroditic connector with locking clip. Screen contacts are prominently visible, gold-plated signal contacts less so.
The IBM 8228 Multistation Access Unit with accompanying Setup Aid to prime the relays on each port. The unit is fully passive and does not need a power supply.
Token ring concentrator diagram
Both Token Ring and Ethernet interfaces on the 2210-24M
