Centralized Routing vs. Distributed Routing Protocols

Difference Between Centralized Routing and Distributed Routing Protocols

Routing is the process of choosing the paths to be used to send network traffic and sending packets along the sub network chosen. In computer networking terminology, a routing protocol defines how the nodes in the networks (especially the routers) communicate with one another, decide the paths that are to be chosen to send traffic network by sharing important link information. Usually the nodes have the initial knowledge of other nodes that are connected to it directly and the routing protocol will extend this information first to the nearby and then to other nodes. This is how the routing protocols provide the knowledge of network topology of the network routers at the start as well as after a change has occurred.

Dynamic and static are the types of routing protocols known. The static protocols work only with routing tables that are manually configured, whereas updating the routing table (s) as per changes in network topology is done by dynamic protocol adaptively. Dynamic protocols are divided further as distributed and centralized. The focus of centralized protocols is on a central node for all the routing decision, while the distributed protocols make each device in the network responsible for routing decisions.

What is Centralized Routing Protocols?

As mentioned above, a centralized routing protocol belongs to the family of dynamic routing protocols. In a network using a centralized, routing protocol a central processing device that runs on a “central” node collects information (the status as up / down status, capacity and current use) on each link in the network. Routing tables for all other nodes is calculated using the information gathered by this device processing. The routing protocols take advantage of a centralized database found at the central node for these accounts. In other words, the routing table is kept to single “central” nodes, which need to be consulted when other nodes make routing decision.

What is Distributed Routing Protocols?

Distributed routing protocols also belong to the family dynamic routing protocols. According to the protocol distributed routing, each device in the network is responsible for routing decisions. There are two types of dynamic distributed protocols, called isolated and non-isolated. Isolated are those nodes that do not communicate, while non-isolated ones communicate. Thus under this category sub (dynamic, distributed and non-isolated), there are two broad classes of protocols that are used most commonly today. They are distance vector protocols and link state protocols. Information such as cost at regular intervals, destination, etc are made to share by the nodes by the distance-vector protocols. The link-state protocols flood the link state information throughout the network to allow each node to build a network ‘map’.

How can you differentiate between Centralised Routing Protocols and Distributed Routing Protocols?

Though both centralized and distributed routing protocols are dynamic routing protocols, they are quite different about how they operate. The main difference between them is based on which devices in the network make decisions about routing. A central node is responsible for all routing decisions in centralized routing, as each device is responsible for routing decisions according to the distributed protocols. Centralized protocols have many problems compared to distributed protocols, such as having a single point of failure and potential traffic congestion around the central node. Because of these reasons, distributed protocols are more commonly used.


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