Routing is an important function in computer networking that involves directing data packets from one device to another across a network. It ensures that information reaches its destination efficiently and accurately. Routers are the key devices responsible for making routing decisions in a network. A detailed tutorial can be found here.

Routing is divided into two categories.

1. Static Routing
2. Dynamic Routing

Understanding Static Routing

Static routing is a routing method where network administrators manually configure the routing table on a router. In this approach, the routing decisions are predetermined and do not change unless modified by the administrator. Static routing is straightforward and suitable for small networks with a relatively simple topology.

How Static Routing Works

Configuration

Network administrators manually enter routing information into the router’s configuration. This includes specifying the destination IP addresses and the corresponding next-hop routers.

Routing Table

The router builds a static routing table based on the configured information. This table is used to determine the appropriate path for forwarding data packets.

No Adaptability

One drawback of static routing is its lack of adaptability. If there are changes in the network topology, such as the addition of new devices or alternate routes, administrators must update the routing configuration manually.

Advantages and Disadvantages of Static Routing

Advantages

• Simplicity: Static routing is simple to configure and easy to understand.
• Low Overhead: It has lower overhead on router resources since there’s no dynamic routing protocol running.

Disadvantages

• Lack of Adaptability: Static routing doesn’t adapt well to changes in network topology.
• Maintenance Challenges: Manual updates are required for any network changes.

Dynamic Routing

Dynamic routing is a more adaptive approach to routing, where routers communicate with each other using routing protocols to dynamically update and share routing information. This allows routers to automatically adjust to changes in the network, making it suitable for larger and more complex network environments.

How Dynamic Routing Works

Routing Protocols

Dynamic routing protocols, such as OSPF (Open Shortest Path First), RIP (Routing Information Protocol), and BGP (Border Gateway Protocol), facilitate communication between routers.

Exchange of Routing Information

Routers share information about the network’s topology, and each router builds and maintains its routing table based on this dynamically acquired information.

Adaptability

Dynamic routing adapts to changes in the network, such as link failures or the addition of new devices, without manual intervention.

Efficient Path Selection

Dynamic routing protocols use algorithms to determine the most efficient path for data packets, considering factors like link cost and network congestion.

Advantages and Disadvantages of Dynamic Routing

Advantages

• Adaptability: Dynamic routing adapts to changes in network topology without manual intervention.
• Efficiency: It can find the most efficient path based on real-time network conditions.

Disadvantages

• Complexity: Dynamic routing protocols can be complex to configure and manage.
• Resource Overhead: Dynamic routing protocols consume more router resources compared to static routing.

Understanding routing, static routing, and dynamic routing is fundamental to designing and maintaining efficient computer networks. The choice between static and dynamic routing depends on factors such as network size, complexity, and the need for adaptability. Each approach has its advantages and disadvantages, and network administrators must carefully consider these factors when implementing routing solutions in their networks.

Material

The presentation slides can be downloaded here.

Self Assessment

• What do you know about routing on computer networks?
• What is the difference between static and dynamic routing?
• You are asked to create a small network for an organization, which routing would you prefer to use and why?