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What is Network Routing and How Does It Work?

by Iwan Price-Evans on Networking • June 6, 2022

Network routing, not to be confused with Application Routing, is the process of determining the path for data to follow through networks via computers and servers. All networks use the same principle of routing whether an internet network, telecommunications network, or even a physical transport network. Each has a set of rules, routes, and destinations that decisions can be taken on.

Networks that carry data packets, or packet-switching networks, often use the Internet Protocol (IP) to transfer data to their destination.

What is IP routing?

IP routing describes the actual forwarding of IP data packets by routers, specifically, the steps routers take to do this.

A router is a physical device that acts as a gateway to a network. It receives and forwards data packets or messages to destination devices in the current network or in other connected networks.

How does IP routing work?

When data is transmitted across single or multiple networks, it travels from its source router through other routers and networks until it reaches its destination router. This routing process is enabled by the router using a routing algorithm. 

Routing Algorithms

A routing algorithm makes decisions on the best path for the data to take to its destination. When making these decisions it will take into account factors like the size of the data packets and the required destination. 

Each data packet has a header that contains important destination information. The router's algorithm will look at the header destination and determine which route to send the packet on. It's very similar to having a plane ticket that contains a destination. The ticket is checked and the passenger is directed to the right plane for that destination.

Routing Tables

Routing tables are like an address book: they're a database of network locations of routers and their IP addresses.

The routing algorithm refers to the routing tables to identify the most efficient path to the destination. This enables it to decide which router to send the data to next. Without routing tables, routers can't decide how to get their data packets and messages to their destination. 

Routing Hops

When a packet reaches a router the source and destination information in the packet header are used, in conjunction with a routing table, to determine the next network segment to send it to. This process is described as a network 'hop'. The term represents the 'hops' data packets take from one router to the next.

Each router repeats the process, referring to its own routing table until the packet reaches its destination. Each data packet travels independently from the others. This means that packets can be sent through different routes to the destination depending on what the routing algorithms decide.

Routing protocols

Networking protocols are a standardized way for computers to understand data sent over networks. These protocols are specifically designed for routing and are used for identifying and communicating network paths.

Common routing protocols:

  • Internet Protocol (IP) - This specifies the source and destination addresses for each data packet.
  • Border Gateway Protocol (BGP) - This protocol tells routers which networks are connected and which IP addresses they control.
  • Routing Information Protocol (RIP) - This protocol determines the shortest path from one network to the next and uses the 'hop count' to do this. The 'hop count' is the number of routers the data packet has to 'hop' to get to its destination.
  • Open Shortest Path First (OSPF) - Can be used when a router needs to find the shortest, and hopefully the fastest, route to the destination.