Bruce Hartpence - Packet Guide to Routing and Switching

Copyright 2011 Bruce Hartpence

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As this book contains both ground-up explanations and advanced ideas, it is appropriate for those just beginning as well as the pros out there, who might need a refresher. Whether you are working with small networks or interconnecting larger ones, the principles contained remain true.

This book is meant to be a companion to The Packet Guide to Core Network Protocols . Both books stand on their own, but this book assumes that you understand the concepts and protocols explained previously, including ARP, ICMP, IP, equipment, Ethernet, and masking. Occasionally Ill throw in a little review, but these sections will be few and far between.

This chapter ties the book together, covering the integrated nature of the forwarding decisions made on the network and introduces many of the concepts that form the basis of later chapters. The chapter addresses key ideas, including classification of protocols, static versus dynamic topologies, and the reasons for installing a particular route.

This chapter picks up where the discussion of masks in leaves off. Hosts are like routers in many ways, and possessing a routing table is just one of them. Reading this chapter will show you how to process a host routing table and how traffic starts out across a network. Conversations crossing routers will also be examined, with special attention paid to addressing and frame construction.

Loops are problematic for Ethernet networks. The Spanning Tree Protocol is an integral part of every network containing switches and works to protect the topology against them. It can also affect the performance of your network and consume bandwidth. This chapter covers Spanning Tree and the faster Rapid Spanning Tree protocol.

As good as switches have been for modern communication topologies, once the Layer 2 network grows beyond a certain size, bottlenecks and security concerns start to assert themselves. VLANs are a valuable tool used to address these problems. This chapter covers the design and operation of VLANs and includes sections for trunking protocols that allow VLANs to spread out over many switches.

One of the first distance vector protocols, RIP is often used as a basis for understanding dynamic routing. However, RIP also has a place in small, modern communication networks. This chapter addresses the operation and structure of RIP. Also discussed are improvements to simple dynamic routing, including split horizon, poisoning, count to infinity, and triggered updates.

OSPF is a link state protocol, and as such, is generally considered superior to protocols like RIP. This chapter will explain the operation of link state protocols and why convergence times are improved over distance vector. The protocol structure, addressing, and operation will be covered with support from packet captures.

The following typographical conventions are used in this book: