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Cisco Express Forwarding

Book

  • Sorry, this book is no longer in print.
Not for Sale
  • Description
  • Sample Content
  • Updates
  • Copyright 2007
  • Edition: 1st
  • Book
  • ISBN-10: 1-58705-236-9
  • ISBN-13: 978-1-58705-236-1

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Cisco Express Forwarding

Understanding and troubleshooting CEF in Cisco routers and switches

Nakia Stringfield, CCIE® No. 13451

Russ White, CCIE No. 2635

Stacia McKee

How does a router switch a packet? What is the difference between routing a packet, switching a frame, and packet switching? What is the Cisco® Express Forwarding (CEF) feature referred to in Cisco documentation and commonly found in Cisco IOS® commands? CEF is a general term that describes the mechanism by which Cisco routers and Catalyst® switches packet-switch (route) frames. CEF is found in almost all Cisco routers and Catalyst switches, and understanding how CEF operates can improve the performance, scalability, and efficiency of your network.

Cisco Express Forwarding demystifies the internal workings of Cisco routers and switches, making it easier for you to optimize performance and troubleshoot issues that arise in Cisco network environments. This book addresses common misconceptions about CEF and packet switching across various platforms, helping you to improve your troubleshooting skills for CEF- and non-CEF-related problems.

The first part of the book provides an overview of packet-switching architectures and CEF operation and advanced features. It also covers the enhanced CEF structure and general troubleshooting. The second part of the book provides case studies that focus on the common topics that have been problematic for customers and those supporting Cisco networks.

Full of practical examples and configurations, this book draws on years of experience to help you keep your Cisco networks running efficiently.

Nakia Stringfield, CCIE® No. 13451, is a network consulting engineer for Advanced Services at Cisco, supporting top financial customers with network design and applying best practices. She was formerly a senior customer support engineer for the Routing Protocols Technical Assistance Center (TAC) team troubleshooting issues related to CEF and routing protocols. Nakia has been with Cisco for more than six years, previously serving as a technical leader for the Architecture TAC team.

Russ White, CCIE No. 2635, is a Principle Engineer in the Routing Protocol Design and Architecture team at Cisco. He is a member of the IETF Routing Area Directorate, co-chair of the Routing Protocols Security Working Group in the IETF, a regular speaker at Cisco Networkers, a member of the CCIE Content Advisory Group, and the coauthor of six other books about routing and routing protocols, including Optimal Routing Design from Cisco Press. Russ primarily works in the development of new features and design architectures for routing protocols.

Stacia McKee is a customer support engineer and technical leader of the Routing Protocols Technical Assistance Center (TAC) team. This team focuses on providing post-sales support of IP routing protocols, MPLS, QoS, IP multicast, and many other Layer 3 technologies. Stacia has been with Cisco for more than six years, previously serving as a technical leader of the Architecture TAC team and a member of the WAN/Access TAC team.

  • Learn the key features of packet-switching architectures
  • Understand the basics of the CEF architecture and operation
  • E

Online Sample Chapter

Basic IP Connectivity and Troubleshooting in Cisco Express Forwarding

Downloadable Sample Chapter

Download - 275 KB -- Chapter 4: Basic IP Connectivity and CEF Troubleshooting

Table of Contents

Part I    Understanding, Configuring, and Troubleshooting CEF 3

Chapter 1    Introduction to Packet-Switching Architectures 5

Routing and Switching 5

    Understanding Broadcast and Collision Domains 5

    Layer 3 Switching 8

Understanding Router Pieces and Parts 9

    Interface Processors 10

    Central Processing Unit 11

    Memory 11

    Backplanes and Switching Fabrics 11

Cisco IOS Software: The Brains 17

    Memory Management 17

    Interaction with Interface Processors 28

Processes and Scheduling 28

    Process Memory 28

    Process Scheduling 29

Putting the Pieces Together: Switching a Packet 35

    Getting the Packet off the Network Media 35

    Switching the Packet 39

    Transmitting the Packet 44

Hardware and Software show Commands 45

Summary 48

Chapter 2    Understanding Cisco Express Forwarding 51

Evolving Packet-Switching Methods 51

    Process Switching 51

    Fast Switching 52

    What Is CEF? 53

CEF Tables 54

    Forwarding Information Base (FIB) 54

    The Adjacency Table 60

    Relating the CEF Tables 61

CEF Table Entries 62

FIB Entries 62

Generic FIB Entries 67

Interface-Specific FIB Entries 68

    FIB Entries Built for a Multiaccess Network Interface 68

    FIB Entries Built on a Point-to-Point Network Interface 69

Index

Download - 275 KB -- Index

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