IBM CTI 2572 User Manual
CTI 2572 Technical Overview Manual
4
2.2 IEEE 802.5 (Token-Ring)
Token Ring (IEEE 802.5) uses a ring topology.
Each station on the network has two
connections - one to the "downstream" station
and one to the "upstream" stations. Each
station receives network data from the
downstream station and passes it to the
upstream station. The data circulates through
the network until it reaches the initiating
station, which validates that it was correctly
sent though the network. In practice, rather
than wire directly between each station, the
stations are wired into a central hub. This
approach allows stations to be added by
plugging them into the hub, where the plug
mechanically inserts the station into the ring.
Token ring operates at 4 or 16 M bits/sec using
shielded twisted pair media. Fiber optic cable
may be used for interconnecting hubs.
Each station on the network has two
connections - one to the "downstream" station
and one to the "upstream" stations. Each
station receives network data from the
downstream station and passes it to the
upstream station. The data circulates through
the network until it reaches the initiating
station, which validates that it was correctly
sent though the network. In practice, rather
than wire directly between each station, the
stations are wired into a central hub. This
approach allows stations to be added by
plugging them into the hub, where the plug
mechanically inserts the station into the ring.
Token ring operates at 4 or 16 M bits/sec using
shielded twisted pair media. Fiber optic cable
may be used for interconnecting hubs.
Token Ring (802.5) uses a "token" which is passed among the stations on the network. When a
station has a token, it can transmit. When it is through transmitting data, a station sends the
token to the next "upstream" station.
station has a token, it can transmit. When it is through transmitting data, a station sends the
token to the next "upstream" station.
The primary benefit of token ring is that it provides a very consistent level of network
performance, since there is a maximum amount of time a token can be held. Token Ring
response is sometimes referred to as deterministic, meaning that the response time can be
precisely calculated. At higher levels of network loading, Token-Ring may provide greater
sustained throughput than Ethernet or Token-Bus.
performance, since there is a maximum amount of time a token can be held. Token Ring
response is sometimes referred to as deterministic, meaning that the response time can be
precisely calculated. At higher levels of network loading, Token-Ring may provide greater
sustained throughput than Ethernet or Token-Bus.
On the other hand, token ring is costly (about 4 to 5 times more than Ethernet) and its technology
is closely tied to proprietary IBM technology. In some situations, the ring topology of token-ring
networks may not be as well suited to the factory floor as a bus topology.
is closely tied to proprietary IBM technology. In some situations, the ring topology of token-ring
networks may not be as well suited to the factory floor as a bus topology.
PC
PC
PC
Server
PC
PC
Figure 2 Token Ring Topology