Interior Versus Exterior Routing Protocols

Last Updated on Thu, 29 Jun 2023 | Network Design

An autonomous system (AS), also known as a domain, is a collection of routers that are under a common administration, such as a company's internal network or an Internet service provider's (ISP's) network.

KEY POINT

Because the Internet is based on the AS concept, two types of routing protocols are required:

■ Interior gateway protocols (IGP) are intra-AS (inside an AS) routing protocols. Examples of IGPs include Routing Information Protocol (RIP) version 1 (RIPv1), RIP version 2 (RIPv2), Open Shortest Path First (OSPF), Integrated Intermediate System-to-Intermediate System (IS-IS), and Enhanced Interior Gateway Routing Protocol (EIGRP).

■ Exterior gateway protocols (EGP) are inter-AS (between autonomous systems) routing protocols. Border Gateway Protocol (BGP) is the only widely used EGP protocol on the Internet. BGP version 4 (BGP-4) is considered the acceptable version of BGP on the Internet. It is discussed in the "Border Gateway Protocol" section.

Different types of protocols are required for the following reasons:

■ Inter-AS connections require more options for manual selection of routing characteristics. EGPs should be able to implement various policies.

■ The speed of convergence (distribution of routing information) and finding the best path to the destination are crucial for intra-AS routing protocols.

Therefore, EGP routing protocol metrics (used to measure paths to a destination) include more parameters to allow the administrator to influence the selection of certain routing paths. EGPs are slower to converge and more complex to configure. IGPs use less-complicated metrics to ease configuration and speed up the decisions about best routing paths for faster convergence. The "Routing Protocol Metrics" section later in this chapter defines and explains routing protocol metrics.

Continue reading here: IGP and EGP Example

Was this article helpful?

0 0

Recommended Books

  • Network Design: A Comprehensive Guide
  • Network Design: Principles and Practices
  • Network Design: Principles and Applications
  • Network Design Cookbook: Architecting Cisco Networks
  • Network Design: A Beginner's Guide
  • Network Design Principles: A Beginner's Guide

Related Posts

Readers' Questions

  • Briffo
    Which are a type of interior gateway protocol?
    1 month ago
    • ) are used to exchange routing information between gateways. This includes both interior gateway protocols like RIP, OSPF, and EIGRP, as well as exterior gateway protocols like BGP. In contrast to routing protocols which are used to exchange information between different networks, interior gateway protocols are used to maintain information within a single autonomous system. They provide metrics to determine the best path for data to pass through the system, as well as facilitating the changing of routes within the system when required.
    • frederick
      Why are different interas and intraas protocols used in the internet?
      8 months ago
      • InterAS and IntraAS protocols are used in the Internet to provide different levels of routing control. InterAS protocols are used to establish communications between different autonomous systems (ASes) and direct traffic between them. IntraAS protocols are used to control communications within a single AS so that traffic can be directed more efficiently within that AS.
      • Sigismond
        What is the most commonly used exterior gateway protocol?
        8 months ago
        • The most commonly used exterior gateway protocol is the Border Gateway Protocol (BGP).
        • maria
          What is the difference between interior and exterior routing protocols?
          8 months ago
          • Interior routing protocols, such as RIP, OSPF, and IS-IS, are used to route traffic within an autonomous system. These protocols calculate the best path for data to travel within the autonomous system and enable routers to exchange information about all the networks that exist within the system. Exterior routing protocols, such as BGP, are used to route traffic between autonomous systems. These protocols allow routers to exchange information about the networks that exist outside of the autonomous system and enable routers to make decisions about how to get to the external networks.