Computer Science - Class 12
Chapter 10 - Computer Networks

## NETWORK TOPOLOGY

The arrangement of computers and other peripherals in a network is called topology. The 6 main network topologies are as follows:

### 1. Mesh Topology

In this topology, each node in the network is connected to every other node in the network.

 Advantages Disadvantages It can handle large amounts of data traffic since multiple nodes can transmit data simultaneously. Large cable length is required. It is more reliable because even if a node is down, it does not cause a break in the transmission of data between other nodes. Wiring is complex. It is also more secure compared to other topologies because each cable between 2 nodes carry different data. High cabling cost. The point to point links in mesh topology makes fault detection easy.

### 2. Ring Topology

In this topology, each node in the network is connected to only 2 nodes , one on either side. The nodes connected with each other thus form a ring. The data travels in one direction only from node to node around the ring.

 Advantages Disadvantages Short cable length is required. The failure of a single node in the network can cause the entire network to fail. The transmission of data is relatively simple as data travels in only one direction. Fault detection is very difficult. It is suitable for long distance communication since each node in the network acts as a repeater and boosts the signal before sending it to the next node. Data has to pass through every node between the sender and the receiver which makes the network slow. Less reliable and less secure.

### 3. Bus Topology

In this topology, each node in the network is connected to a common transmission medium called the bus. The data transmitted from a node travels throughout the entire length of the bus in both directions and it can be received by any node connected to the bus.

 Advantages Disadvantages Very short cable length is required. Only a single message can travel at a particular time. It can be extended easily. The network becomes slow with an increase in the number of nodes. It is cost effective. Less secure and less reliable. Works efficiently in small networks. If the main cable fails, then the entire network fails. Fault detection is difficult.

### 4. Star Topology

In this topology, each node in the network is connected to a central node which is a networking device like a hub/switch. The central node can be either a broadcasting device meaning data will be transmitted to all the nodes in the network, or a unicast device meaning the node can identify the destination and forward data to that node only.

 Advantages Disadvantages Fault detection is easy. Requires more cable length than bus topology. Easy to install. If the hub/switch fails, the entire network fails. Failure of a single node will not bring down the entire network. Installation and maintenance is expensive. High speed network. Highly reliable and secure.

### 5. Hybrid Topology

Hybrid topology is a combination of two or more network topologies.

 Advantages Disadvantages Combines the benefits of different types of topologies. Expensive It is very reliable. Complex design It can handle large volumes of traffic. Installation is difficult Fault detection is easy. Large cable length is required

### 6. Tree Topology

Tree topology is a hybrid network of star and bus topologies . The central node of this topology is called the root node and all the other nodes are connected to the root node in a hierarchical manner.

 Advantages Disadvantages Failure of a single node will not affect the entire network. Installation is difficult Easily extendable. Long cables are required Fault detection is easy. If the main cable fails, the entire network will fail.