Packet Broadband Network Handbook
Providing all of the relevant details on enabling technologies, this easy-to-navigate resource will give you all the context you need to put them in perspective and make well-informed choices.
TABLE OF CONTENTS Packet Broadband Network Handbook
Appendix A: IP Routing Protocols
A.1 Introduction
At the core of the IP layer is a set of routing functions and routing protocols. This appendix discusses how each of the widely used routing protocols operates. Before delving into the protocols themselves, we first introduce the IP network topology, two generic categories of routing algorithms, and the general routing operations at a router as background information for routing protocols.
At the top level, IP networks consist of a set of autonomous systems (AS), in Internet terminology. Each AS is a group of networks that are administrated as a single unit. The concept of AS is related to the fact that TCP/IP protocols were developed with the ARPANET already in place, and the exiting network was treated as an independent AS. Each AS is an administrative unit that may consist of one or more networks. The concept of AS is an important one for IP routing because routing within an AS and routing outside an AS are handled by different types of protocol.
A.1.1 Interior versus Exterior IP Gateway Routing Protocols
All IP routing protocols fall into one of two categories: those used within an autonomous system, called Interior Gateway Protocols (IGP) , and those used between autonomous systems, called Exterior Routing Protocols (ERPs). This appendix describes the most commonly used IGPs, which include the Routing Information Protocol (RIP), the Intermediate System-to-Intermediate System (IS-IS) protocol, and the Open Shortest Path First (OSPF) protocol. The exterior routing protocols include the Exterior Gateway Protocol (EGP) and...
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