What is Routing in Network Layer?
Routing is the process of determining the optimal path for data to travel from its source to its destination across a network. In the network layer of the OSI model, routing is responsible for forwarding data between different networks, using the information provided by the data link layer.
When a host sends data across a network, it includes the destination IP address in the header of the packet. The source IP address is also included, along with other information such as the type of service, protocol, and time-to-live (TTL) value. The router reads this header and uses the destination IP address to determine the best path to forward the data.
There are two main types of routing: static routing and dynamic routing.
Static routing involves manually configuring the routing table on each router in the network. In this approach, the administrator specifies the path for each destination network. Static routing is simple to set up and works well for small networks with a limited number of devices. However, it can be time-consuming and error-prone to manually configure the routing table, especially for larger networks.
Dynamic routing, on the other hand, uses routing protocols to automatically determine the best path for data to travel. Routing protocols enable routers to exchange information about the networks they are connected to, allowing them to build a map of the network topology. This map is used to determine the best path for data to travel based on various factors, such as network congestion and link speed. Some popular routing protocols include the Routing Information Protocol (RIP), Open Shortest Path First (OSPF), and Border Gateway Protocol (BGP).
Once the router has determined the best path for data to travel, it forwards the packet to the next hop along the path. The router updates the header of the packet with its own IP address before sending it on to the next router. This process continues until the packet reaches its destination.
There are different metrics used to determine the best path for data to travel. Some of the most common metrics include hop count, which is the number of routers between the source and destination, and bandwidth, which is the amount of data that can be transmitted over a link in a given time period. Other factors that may be considered include network latency, packet loss, and route stability.
Overall, routing is a critical function of the network layer that enables data to travel between different networks. By determining the optimal path for data to travel, routing helps to ensure that data is delivered quickly and reliably to its intended destination.