Introduction to Token Ring Topology

Token ring topology was introduced in the 1980’s and become a great competitor for Ethernet users. This topology competes with its standards and stood with its technology at high time. Token ring is a structure of data communication between computers in a ring formation. Computers are considered as hosts, and one host is connected to two adjacent hosts forming a circular structured network. When one host trying to send a message, it can be sent to intermediate hosts to identify its nearby machine. So the data travels until it receives to the particular host. When a host fails to receive a message, it results in failure of the entire ring. Then every connection connected to the ring results to failure. A back up can be made by deploying another ring. The frames used to transfer from one host to another is called tokens. And this token is traveled in a logical ring, and the ring can be a workstation or server. This topology traverses the data in a medium where any data can be sent to any computer connected in a network called a contention-based access method.

Why Do We Use Token Ring Topology?

The token ring topology has the speed for transmission in 4 Mbps to 16 Mbps. The whole has the consistency to transmit the tokens at the same speed when configured. In the circular connection of nodes in a ring, the computer is identified using MAU introduced by IBM called Multiple Access Unit. It logically functions inside MAU forming a ring. And works with two types of monitors called standby and active monitor (by default). When the token ring is compared to Ethernet, collision reduction is the greater advantage of the network. Ethernet uses CSMA which transfers the data in a single line direction and blocks the passage. When another computer tries to transmit at the same time, the collision might occur and leads to no data transmission. So, it needs to wait for the next transaction. Where in the token ring, the nodes grant permission for transmitting messages at the same time. Because the host verifies the token and transfers the message. If it doesn’t receive the token it has to wait for its turn. So, it leads to efficient usage of bandwidth by sharing the network equally. Token ring allows larger-sized packets than Ethernet and it can perform very well using the Token passing principle. Ex: When an Ethernet transfers packet at 10Mbps, Token ring can perform the same transaction using Token passing using 4 Mbps.

Importance of Token Ring Topology

Few importance are listed down below.

The token is the pattern of a special bit traveling in the circular path; a computer sends the message containing a token attached to it. This type of continuous passage of message is called token passing.
Token passing is a method of acknowledging a signal received by computer for transmitting the message to one another. So receiving end gets the data and passes the signal to the source with a signal as acknowledgment.
The importance of the token ring topology is, the source sends an empty token with a message and address of the destination. So the token checks for the successive node i.e. address of computer/ host. When the token identifies the node, the receiver copies the data and returns with a receipt containing the source’s address.
So, in the circular path of the transaction, when the actual source receives the token, it verifies the message and copies it. Finally, it empties the token for the same process to continue in the circular model.
These are popularly used in the Local area network and Wide area network.
This topology is firstly introduced by IBM in the Local area network as LAN token ring.
The tokens are mostly traversed in a uni-direction ring topology. But the token ring can work in bi-directional also. The data transfer in uni-direction topology is referred to as half-duplex network and bi-direction topology transfer (data can be sent and received at the same time) called as a full-duplex network.

Benefits & Drawbacks of Token Ring Topology

Below are the benefits & drawbacks of Token Ring Topology:

Benefits:

Packet collision is reduced and the flow of data is managed in only one direction i.e. in the circular.
High-speed data transfer between workstations.
Easier maintenance of the network.
Server is not needed to control the connectivity between every workstation.
Workstations can be added to the network when required, which does not affect the performance of the network.
The high-speed network is provided in a uni-directional network.
Can work efficiently in a longer distanced network.
Though nodes are increased in a ring topology, performance will be better than bus topology.
It is the robust network as the ring topology manage the high number of nodes.
Handles huge traffic communication.
Fault in data transfer can be easily identified in the network through cable connectivity.
Compatible in cost when compared to other network topologies.

Drawbacks:

If one workstation slows down also, the entire network will get collapsed.
The transfer of data must pass on each network’s workstation. It can make slower than other topology.
A small or single disturbance in the network can cause failure in the whole network.
Hardware will be needed to connect between workstations in the network.
Hardware will be needed to connect between workstations in the network.
Expensive will be more when hubs, switches or Ethernet cards are used or introduced to increase efficiency.
As the topology is uni-directional, the data i.e. token should pass the entire network – it should cross through all the nodes.
Though the addition of nodes increases performance, it is difficult to add a node to the existing network and may cause the issue.
During heavy load condition, ring topology can be slower than Ethernet networks.

Conclusion

Token ring performed equally well against Ethernet with the transmission speed. But in the current marketing, Ethernet overtook this topology with speed and pricing too. Token ring becomes too expensive with cable and MAU card compared to Ethernet cards. It got higher than five to six times than the Ethernet card. Ethernet fastens its transaction to 100 Mbps very quickly. Token ring tried to overcome the Ethernet with speed. But it was too late with generation and technology growth.

Introduction to Token Ring Topology