Network Topology
Network topology
Network topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.
Why is network topology important?
Network topology plays a major role in how a network functions. Namely, the topology has a direct effect on network functionality. Choosing the right topology can help increase performance, as a properly chosen and maintained network topology increases energy efficiency and data transfer rates.
Types of Network Topology
There are several types of topologies. For example, physical topologies include the following:
Bus network.
In the bus network topology, every node is connected in series along a single cable. This arrangement is found today primarily in cable broadband distribution networks.
Advantages of Bus topology:
Low-cost cable: In bus topology, nodes are directly connected to the cable without passing through a hub. Therefore, the initial cost of installation is low.
Moderate data speeds: Coaxial or twisted pair cables are mainly used in bus-based networks that support upto 10 Mbps.
Familiar technology: Bus topology is a familiar technology as the installation and troubleshooting techniques are well known, and hardware components are easily available.
Limited failure: A failure in one node will not have any effect on other nodes.
Disadvantages of Bus topology:
Extensive cabling: A bus topology is quite simpler, but still it requires a lot of cabling.
Difficult troubleshooting: It requires specialized test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes.
Signal interference: If two nodes send the messages simultaneously, then the signals of both the nodes collide with each other.
Reconfiguration difficult: Adding new devices to the network would slow down the network.
Attenuation: Attenuation is a loss of signal leads to communication issues. Repeaters are used to regenerate the signal.
Star network.
In the star network topology, a central device connects to all other nodes through a central hub. Switched local area networks based on Ethernet switches and most wired home and office networks have a physical star topology.
Advantages of Star topology
Efficient troubleshooting: Troubleshooting is quite efficient in a star topology as compared to bus topology. In a bus topology, the manager has to inspect the kilometers of cable. In a star topology, all the stations are connected to the centralized network. Therefore, the network administrator has to go to the single station to troubleshoot the problem.
Network control: Complex network control features can be easily implemented in the star topology. Any changes made in the star topology are automatically accommodated.
Limited failure: As each station is connected to the central hub with its own cable, therefore failure in one cable will not affect the entire network.
Familiar technology: Star topology is a familiar technology as its tools are cost-effective.
Easily expandable: It is easily expandable as new stations can be added to the open ports on the hub.
Cost effective: Star topology networks are cost-effective as it uses inexpensive coaxial cable.
High data speeds: It supports a bandwidth of approx 100Mbps. Ethernet 100BaseT is one of the most popular Star topology networks.
Disadvantages of Star topology
A Central point of failure: If the central hub or switch goes down, then all the connected nodes will not be able to communicate with each other.
Cable: Sometimes cable routing becomes difficult when a significant amount of routing is required.
Ring network.
In the ring network topology, the nodes are connected in a closed-loop configuration. Some rings pass data in one direction only, while others are capable of transmission in both directions. These bidirectional ring networks are more resilient than bus networks since traffic can reach a node by moving in either direction. Metro networks based on Synchronous Optical Network technology are the primary example of ring networks.
Advantages of Ring topology:
Network Management: Faulty devices can be removed from the network without bringing the network down.
Product availability: Many hardware and software tools for network operation and monitoring are available.
Cost: Twisted pair cabling is inexpensive and easily available. Therefore, the installation cost is very low.
Reliable: It is a more reliable network because the communication system is not dependent on the single host computer.
Disadvantages of Ring topology:
Difficult troubleshooting: It requires specialized test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes.
Failure: The breakdown in one station leads to the failure of the overall network.
Reconfiguration difficult: Adding new devices to the network would slow down the network.
Delay: Communication delay is directly proportional to the number of nodes. Adding new devices increases the communication delay.
Mesh network.
The mesh network topology links nodes with connections so that multiple paths between at least some points of the network are available. A network is considered to be fully meshed if all nodes are directly connected to all other nodes and partially meshed if only some nodes have multiple connections to others. Meshing multiple paths increases resiliency but also increases cost. However, more space is needed for dedicated links.
Mesh topology is divided into two categories:
Fully connected mesh topology
Partially connected mesh topology
Full Mesh Topology: In a full mesh topology, each computer is connected to all the computers available in the network.
Partial Mesh Topology: In a partial mesh topology, not all but certain computers are connected to those computers with which they communicate frequently.
Advantages of Mesh topology:
Reliable: The mesh topology networks are very reliable as if any link breakdown will not affect the communication between connected computers.
Fast Communication: Communication is very fast between the nodes.
Easier Reconfiguration: Adding new devices would not disrupt the communication between other devices.
Disadvantages of Mesh topology
Cost: A mesh topology contains a large number of connected devices such as a router and more transmission media than other topologies.
Management: Mesh topology networks are very large and very difficult to maintain and manage. If the network is not monitored carefully, then the communication link failure goes undetected.
Efficiency: In this topology, redundant connections are high that reduces the efficiency of the network.
Tree network.
The tree network topology consists of one root node, and all other nodes are connected in a hierarchy. The topology itself is connected in a star configuration. Many larger Ethernet switch networks, including data center networks, are configured as trees.
Advantages of Tree topology
Support for broadband transmission: Tree topology is mainly used to provide broadband transmission, i.e., signals are sent over long distances without being attenuated.
Easily expandable: We can add the new device to the existing network. Therefore, we can say that tree topology is easily expandable.
Easily manageable: In tree topology, the whole network is divided into segments known as star networks which can be easily managed and maintained.
Error detection: Error detection and error correction are very easy in a tree topology.
Limited failure: The breakdown in one station does not affect the entire network.
Point-to-point wiring: It has point-to-point wiring for individual segments.
Disadvantages of Tree topology
Difficult troubleshooting: If any fault occurs in the node, then it becomes difficult to troubleshoot the problem.
High cost: Devices required for broadband transmission are very costly.
Failure: A tree topology mainly relies on main bus cable and failure in main bus cable will damage the overall network.
Reconfiguration difficult: If new devices are added, then it becomes difficult to reconfigure.
Hybrid network.
The hybrid network topology is any combination of two or more topologies. Hybrid topologies typically provide
Advantages of Hybrid Topology
Reliable: If a fault occurs in any part of the network will not affect the functioning of the rest of the network.
Scalable: Size of the network can be easily expanded by adding new devices without affecting the functionality of the existing network.
Flexible: This topology is very flexible as it can be designed according to the requirements of the organization.
Effective: Hybrid topology is very effective as it can be designed in such a way that the strength of the network is maximized and weakness of the network is minimized.
Disadvantages of Hybrid topology
Complex design: The major drawback of the Hybrid topology is the design of the Hybrid network. It is very difficult to design the architecture of the Hybrid network.
Costly Hub: The Hubs used in the Hybrid topology are very expensive as these hubs are different from usual Hubs used in other topologies.
Costly infrastructure: The infrastructure cost is very high as a hybrid network requires a lot of cabling, network devices, etc.