Network Topology

Now we going to see about topology and its types. Network topology defines the structure of the network.One part of the topology definition is the physical topology, which is the actual layout of the wire or media. The other part is the logical topology, which defines how the media is accessed by the hosts for sending data.

Physical Topology

• It refers to the interconnected structure of a local area network (LAN). 
• It is created to record where each hosts is on the network.
• The method employed to connect the physical devices on the network with cables, media etc.

Logical Topology

• It is a concept in networking that defines the architecture for communications in all nodes of the network.
• It shows how the host (computer) uses the network, host names, addresses, groups, applications.
• Using routers and switches the logical topology of the network can be dynamically maintained and reconfigured.

The network topologies are classified into following types

• Bus Topology
• Star Topology
• Mesh Topology
• Ring Topology
• Hybrid Topology
• Wireless Topology

BUS TOPOLOGY
 
A bus topology is a single backbone cable that is terminated at both ends. All the hosts are directly connected to the backbone.

Advantages

• It is easy to set-up and extend bus network.
• Cable length required for the topology is least compared to other network.
• Cost is less.
• It is good for LAN.

Disadvantages

• Difficult reconnection and fault isolation.
• If the main cable encounters problem, then whole network will breaks down.
• Proper termination is required to dump signals. Use of terminators is must.
• It is difficult to detect and troubleshoot fault at individual station.
• Maintenance costs is high.
• Efficiency of Bus network reduces, as the number of devices connected to it increases.
• It is not suitable for networks with heavy traffic. 
•  Security is very low because all the computers receive the sent signal from the source.