Difference Between Physical and Logical Topology

In networking the topologies can be classified into two types in its most fundamental way. The former is physical topology, and the latter one is the logical topology, the physical topology specifies the structuring of the network while logical topology describes the communication mechanism used by devices on the LAN for the transmission of the data.

Now, let’s understand what is a network topology, before understanding types of it. A Network Topology describes how various electronic devices can be connected. The chosen topology can highly affect the working of a network.

Content: Physical Topology Vs Logical Topology

1. 1. 1. Comparison Chart
      2. Definition
      3. Key Differences
      4. Conclusion

Comparison Chart

Basis for comparison	Physical topology	Logical topology
Basic	Refer to how a network look and functions.	Fashion in which data travels logistically.
Types	Bus, star, ring and mesh topologies.	Logical bus and the logical ring.
Founded on	Physical connections of cables and devices.	Path traveled by data in a network.
Can affect	Cost, scalability, flexibility, bandwidth capacity, etcetera.	Data delivery causing lost packets or congestion.

Definition of Physical Topology

Physical topology can be considered as a layout of the network media that shows the interconnections of the devices on the network. It specifies which geometric shape the linked devices form with each other. The physical topology does not give much comprehensive detail about the type of devices, the mechanism used for interacting with other devices in the network, and how data is transferred from one device to another.

Therefore, it gives essential details of the network and network devices broadly, neglecting the higher level details like device type, addressing schemes, connectivity, and so on.

The factors that affect communication of devices on a network based on the physical topology selected are:

• Cost
• Scalability
• Bandwidth capacity
• Ease of installation
• Ease of troubleshooting

Types of Physical Topology

Some commonly used physical topologies are the bus, ring and star.

1. Bus topology – Comprised of a single main cable, with which all the devices or pc’s are connected. There is a terminator attached with the cable, in the end, to absorb the signals when it reaches the end of the line.
2. Ring topology – This topology connects all the devices of the network by forming a ring and the flow of data will always be in one direction. It does not require any termination of the cable, as a result, each device has an equal opportunity to access the media. There are two types of ring topology – single ring and dual ring.
3. Star topology – In this topology, all the devices are linked to a central hub by its own cable.
4. Mesh topology – This topology link each device with every other devices in the network.

Definition of Logical Topology

Unlike physical topology, the logical topology emphasis on the manner in which data is transmitted between network nodes instead of the physical layout of the path that data follows. An important fact regarding these topologies is that both physical and logical topologies are independent regarding a network, whether it is of any shape and size.

As a logical topology is a signal path that passes through a physical topology. It handles the –

• Line discipline
• Ordered delivery of frames
• Error notifications
• Optimal flow control.

Types of Logical Topology

1. Logical Bus – The data follows a linear pattern from the source to all destinations.
2. Logical Ring – In this topology, the data travels in the form of a ring from a device to another and reaches to the beginning of the circle.

Conclusion

Network topology is a crucial part of networking as it is the base for laying the network efficiently. Both the physical and logical topologies hold equal importance for designing and implementing a network. The physical topology can induce the cost and scalability factors while logical topology could leave a negative impact on the data travelling in the form of packets, if not planned carefully.