HP Certified: HP-UX System Administration

IBM developed token ring and it provides a base for IEEE 802.5 token ring specification. The transmission media is twisted pair cable most of the time. Typical token ring networks support 4 Mbits per second and 16 Mbits per second data transfer speeds.

The HP Token Ring/9000 product provides IEEE 802.5 functionality and supports up to 255 stations on a token ring network. A 9-pin D-type connector or an RJ-45 connector is used to connect a host to the network. Physically, a token ring network is not really a ring topology network. It is more similar to a star network.

A data token is passed from one host to another in the network in a predefined sequence. If a host wants to transmit data, it waits for the token. When it receives the token, it attaches its data to the token and passes it to the next host in the sequence. Each host on the way checks if the attached data are for it. If the destination address does not match the host address, the token is passed to the next host until it reaches the destination host. The receiving host detaches the data, frees the token, and passes to the next host. One of the hosts on a token ring network monitors the token activity so that if a token is lost, it generates a new one. In case a destination host dies and nobody can receive data attached to the token, this host detaches the data and marks the token as free again.