Centralized routing vs Distributed Routing Protocols

Routing involves choosing the paths to use to send network traffic and sending packets along the selected sub-net. In computer network terminology, a routing protocol defines how network nodes (especially routers) interact to decide which paths to choose for sending network traffic by sharing the necessary link information.

As a general rule, the nodes have an initial knowledge of the other nodes which are directly connected to it and the routing protocol transmits this information first to the nearest nodes, then to the other nodes. This is how routing protocols inform network routers of the network topology, as well after a change has occurred.

Types of Routing Protocols:

There are two types of routing protocols classified as

  1. Static protocols
  2. Dynamic protocol.

Static protocols only work with manually configured routing tables, while dynamic protocols adaptively update routing tables based on changes to the network topology.

Dynamic protocols are further classified as centralized and distributed. Centralized protocol focus on a central node for all routing decisions, while distributed protocol give each device on the network the responsibility for making routing decisions.

What are centralized routing protocols ?

As mentioned above, centralized routing protocols belong to the family of dynamic routing protocols. In a network that uses a centralized routing protocol, a central processing device running on a “central” node collects information (state such as ascent / descent state, capacity and current usage) on each link in the network.

Then, this processing device uses the information collected to calculate routing tables for all the other nodes. These routing protocols use a centralized database located at the central node for these calculations. In other words, the routing table is kept on a single “central” node, which must be consulted when other nodes have to make a routing decision.

What are distributed routing protocols?

Distributed routing protocols also belong to the family of dynamic routing protocols. Under the distributed routing protocol, each device on the network is responsible for making routing decisions. There are two types of dynamic distributed protocols called isolation (the nodes do not communicate) and non-isolated (the nodes communicate with each other)

Thus, in this sub-category (dynamic, distributed and not isolated), there are two main classes of protocols that are used more commonly today. These are distance vector protocols and link state protocols. Distance vector protocols allow nodes to share information such as destination and cost at regular intervals or as needed. The protocols

What is the difference between centralized routing protocols and distributed routing protocols?

Although centralized and distributed routing protocols are dynamic routing protocols, their operation is very different. The main difference between them is the network devices that make the routing decisions. A central node is responsible for all routing decisions in centralized routing, while each device is responsible for routing decisions in distributed protocols.

Centralized protocols pose many problems compared to distributed protocols, such as the single point of failure and the potential congestion of the network around the central node. For these reasons, distributed protocols are more commonly used.