4.2 Dynamic Routing Protocols (RIP, EIGRP, OSPF, BGP)

Key Concepts

• Routing Information Protocol (RIP)
• Enhanced Interior Gateway Routing Protocol (EIGRP)
• Open Shortest Path First (OSPF)
• Border Gateway Protocol (BGP)

Routing Information Protocol (RIP)

RIP is a distance-vector routing protocol that uses the hop count as its metric. It is one of the oldest routing protocols and is primarily used in small to medium-sized networks. RIP updates are sent every 30 seconds, and it supports a maximum hop count of 15, making it unsuitable for large networks.

Example: Think of RIP as a postal service that delivers letters by counting the number of mailboxes (hops) between the sender and the recipient. If the mailbox count exceeds 15, the letter is returned as undeliverable.

Enhanced Interior Gateway Routing Protocol (EIGRP)

EIGRP is an advanced distance-vector routing protocol developed by Cisco. It uses a composite metric that includes bandwidth, delay, load, and reliability. EIGRP is known for its fast convergence and efficient use of network resources. It supports both IPv4 and IPv6 and is widely used in enterprise networks.

Example: Imagine EIGRP as a courier service that not only counts the number of stops (hops) but also considers the speed of each leg (bandwidth), the time taken (delay), and the reliability of each route. This ensures that packages (data packets) are delivered quickly and efficiently.

Open Shortest Path First (OSPF)

OSPF is a link-state routing protocol that uses the Shortest Path First (SPF) algorithm to determine the best path to a destination. OSPF creates a detailed map of the network, known as a link-state database, and calculates the shortest path tree for each router. It is suitable for large and complex networks and supports hierarchical routing through areas.

Example: Think of OSPF as a GPS system that maps out all possible routes (link-state database) and calculates the shortest path (SPF algorithm) to the destination. This ensures that drivers (data packets) reach their destination quickly and efficiently, even in complex road networks.

Border Gateway Protocol (BGP)

BGP is an exterior gateway protocol used for routing between different autonomous systems (ASes) on the internet. BGP uses path-vector routing, where each route includes a list of ASes that the route has traversed. BGP is responsible for the global routing of internet traffic and is critical for internet connectivity.

Example: Consider BGP as an international shipping company that coordinates the delivery of packages (data packets) across multiple countries (ASes). Each package includes a detailed itinerary (path-vector) of the countries it has passed through, ensuring smooth and reliable international delivery.