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Exploring IGP and EGP (Interior and Exterior Gateway Protocols)

In this tutorial, we’ll cover IGP (Interior Gateway Protocols) and EGP (Exterior Gateway Protocols), which are crucial in routing data across networks. We’ll also take a look at the concept of Autonomous Systems and how these protocols help manage data traffic both within and between networks.

Understanding Autonomous Systems

To learn about IGP and EGP, you need to understand the concept of autonomous systems. An Autonomous System (AS) consists of a group of connected routers and networks under the control of one or more network operators, presenting a common routing policy to the internet. Each AS is assigned a unique identifier known as the Autonomous System Number (ASN), which facilitates routing traffic between ASes.

Think of an Autonomous System (AS) as a large corporation with various departments under a single management. Just as a corporation operates with centralized leadership and policies, an AS comprises routers and networks managed under a single administrative domain, following a consistent set of routing rules.

An Autonomous System serves as a fundamental unit in the architecture of the internet, comparable to a branch within a corporation, with network administrators acting like the executives making strategic decisions to connect and cooperate with other Autonomous Systems. This structure enhances operational efficiency and ensures that the vast network of the internet remains manageable and efficient.

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Understanding IGP and EGP

Routing protocols are divided into two categories, Interior Gateway Protocols (IGP) and Exterior Gateway Protocols (EGP), based on their usage within or between autonomous systems, respectively.

Interior Gateway Protocols (IGPs) are protocols used within a single autonomous system (AS) to facilitate data routing. They optimize the delivery of packets within the autonomous systems’s boundaries. Conversely, Exterior Gateway Protocols (EGPs) are used to route data between different autonomous systems, facilitating broader internet connectivity.

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Interior Gateway Protocols (IGPs)

IGPs act like local traffic laws, managing the flow within a single network or an Autonomous System (AS). They ensure data moves through routers efficiently, making each packet’s journey smooth and streamlined. Here are some common IGPs:

RIP (Routing Information Protocol):

An older, simpler protocol that measures the distance by counting hops from source to destination, favoring routes with fewer hops. It’s ideal for smaller networks where simplicity is a priority.

OSPF (Open Shortest Path First):

OSPF acts like a high-tech GPS for larger networks, evaluating paths based on data transmission speed and network congestion, always seeking the fastest route.

ISIS (Intermediate System to Intermediate System):

This protocol is used primarily within large service provider networks. It determines the best paths for data packets based on a method of shortest path first (SPF), similar to OSPF, but often preferred for its ability to scale efficiently in large or complex topologies.

EIGRP (Enhanced Interior Gateway Routing Protocol):

Developed by Cisco, EIGRP is known for its speed and efficiency. It uses a unique algorithm to determine the best path and can quickly adapt to changes in the network, making it a robust choice for medium to large networks.

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Exterior Gateway Protocols (EGPs)

EGPs manage the broader routes between different cities, or in networking terms, between different Autonomous Systems. These protocols are vital for maintaining the global connectivity of the internet.

BGP (Border Gateway Protocol):

BGP functions like an air traffic controller for the internet, managing data travel across diverse networks, ensuring that packets can traverse the globe no matter the complexity of their routes. Understanding BGP and its configuration is crucial for network engineers involved in large-scale network operations.

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Next >>> Introduction to BGP Protocol

Previous >>> Distance Vector vs. Link State Routing Protocols

Further reading : Wikipedia