Inside Cisco IOS Software Architecture

by Vijay Bollapragada, Russ White, Curtis Murphy

Overview

An essential guide to understanding the Cisco IOS architecture

In-depth coverage of Cisco's IOS Software architecture provides crucial information to:

• Prevent network problems and optimize performance through more efficient design and configuration
• Isolate and resolve network problems more quickly and easily
• Apply the appropriate packet switching method, such as process switching, fast switching, optimum switching, or Cisco Express Forwarding (CEF)
• Understand the hardware architecture, packet buffering, and packet switching processes for shared memory routers (Cisco 1600, 2500, 3600, 4000, 4500, and 4700 series)
• Understand the hardware architecture, packet buffering, and packet switching processes for the Cisco 7200 series routers
• Understand the hardware architecture, packet buffering, and packet switching processes for the Cisco 7500 series routers
• Understand the hardware architecture, packet buffering, and packet switching processes for the Cisco GSR 12000 series routers
• Further your knowledge of how IOS Software implements Quality of Service (QoS)

Inside Cisco IOS Software Architecture offers crucial and hard-to-find information on Cisco's Internetwork Operating System (IOS) Software. IOS Software provides the means by which networking professionals configure and manage Cisco networking devices. Beyond understanding the Cisco IOS command set, comprehending what happens inside Cisco routers will help you as a network designer or engineer to perform your job more effectively. By understanding the internal operations of IOS Software, you will be able to take architectural considerations into account when designing networks and isolate problems more easily when troubleshooting networks. Inside Cisco IOS Software Architecture provides essential information on the internal aspects of IOS Software at this level, and it is an invaluable resource for better understanding the intricacies of IOS Software and how it affects your network.

Inide Cisco IOS Software Architecture begins with an overview of operating system concepts and the IOS Software infrastructure, including processes, memory management, CPU scheduling, packet buffers, and device drivers, as well as a discussion of packet switching architecture with detailed coverage of the various platform-independent switching methods, including process switching, fast switching, optimum switching, and Cisco Express Forwarding (CEF). The book then delves into the intricate details of the design and operation of platform-specific features, including the 1600, 2500, 4x00, 3600, 7200, 7500, and GSR Cisco routers. Finally, an overview of IOS Quality of Service (QoS) is provided, including descriptions of several QoS methods, such as priority queuing, custom queuing, weighted fair queuing, and modified deficit round robin.

Product Details

ISBN-13:	9780132796859
Publisher:	Pearson Education
Publication date:	07/28/2008
Sold by:	Barnes & Noble
Format:	eBook
Pages:	240
File size:	4 MB

About the Author

Curtis Murphy, CCIE #1521, is an engineer in Cisco's Serviceability Design Department in Research Triangle Park, specializing in IOS software products. He has worked in the networking industry since 1989 and at Cisco since 1994. While at Cisco, he has worked both as an IBM protocols specialist in the Technical Assistance Center and as a software engineer in IOS Software Development for mid-range and high-end routers.

Russ White, CCIE #2635, is a member of the IOS Network Protocols Deployment and Scalability Team at Cisco, where he is involved in the design and implementation of routing protocols and scalable network design.

Vijay Bollapragada, CCIE #1606, is currently a manager in the Solution Engineering team at Cisco, where he works on new world network solutions and resolves complex software and hardware problems with Cisco equipment. Vijay also teaches Cisco engineers and customers several courses, including Cisco Router Architecture, IP Multicast, Internet Quality of Service, and Internet Routing Architectures. He is also an adjunct professor in Duke University's electrical engineering department.

Table of Contents

1. Fundamental IOS Software Architecture 2

Operating Systems Basics. CPU Resource Management and Multitasking. Memory Resource Management. Interrupts. IOS Architecture Overview. Memory Organization. Memory Pools. IOS Processes. Process Life Cycle. IOS Process Priorities. Process Examples. IOS Kernel. The Scheduler. The Memory Manager. Packet Buffer Management. System Buffers. Device Drivers. Summary.

2. Packet Switching Architecture.

Routing 101: Process Switching. Traffic Load Sharing with Process Switching. Disadvantages of Process Switching. Fast Switching: Caching to the Rescue. Fast Cache Organization. Maintaining the Cache. Traffic Load Sharing Considerations with Fast Switching. Optimum Switching. Cisco Express Forwarding. How CEF Works. Traffic Load Sharing with CEF. Summary.

3.Shared Memory Routers.

Hardware Architecture for Shared Memory Routers. CPU. Memory. Interface Controllers. Packet Buffers for Shared Memory Routers. Private Buffer Pools. Receive Rings and Transmit Rings. Packet Switching on a Shared Memory Router. Receiving the Packet. Switching the Packet. Transmitting the Packet. Summary.

4. Early Cbus Routers.

AGS+ Hardware Architecture. Packet Switching with the Cbus. Autonomous Switching. Cbus Fast Packet Memory. The Cisco 7000 Series Router. Summary.

5. Particle-Based Systems.

Buffer Management Using Particles. Particle Pools. Particle Coalescing. The Cisco 7200 Series Routers. Hardware Architecture. Memory. Packet Switching on the Cisco 7200 Series Routers. Packet Receive Stage. Packet Switching Stage. Packet Transmit Stage. Summary.

6. Cisco 7500 Routers.

Hardware Architecture of the Cisco 7500 Router. The Data Bus. Route Switch Processor. Packet Switching on the Cisco 7500 Router. RSP Switching: Receiving the Packet. RSP Switching: Switching the Packet. RSP Switching: Transmitting the Packet. VIP Architecture. VIP Components. VIP Models. VIP Packet Operations: Distributed Switching. VIP Receive Side Buffering. Troubleshooting Tips for the Cisco 7500 Router. High CPU Utilization. Input Drops. Ignores. Output Drops. Summary.

7. The Cisco Gigabit Switch Router: 12000.

Hardware Architecture. Switching Fabric. Maintenance Bus. Gigabit Route Processor. Line Card. Packet Switching. Packet Switching: Engine 0 and Engine 1. Packet Switching: Engine 2 LC. Packet Switching: Switching Cells across Fabric. Packet Switching: Transmitting Packets. Summary.

8. Quality of Service.

QoS Overview. Congestion Management. Congestion Avoidance. Priority Queuing. Configuring and Monitoring Priority Queuing. Custom Queuing. Weighted Fair Queuing. Platform-Independent WFQ. Configuring and Monitoring WFQ. Distributed Weighted Fair Queuing. Modified Deficit Round Robin. Configuration of MDRR. Weighted Random Early Detection. Configuration and Monitoring of WRED. Selective Packet Discard. Other QoS Features. Summary.

9. NetFlow Switching 200.

Flow Cache Maintenance. Flow Export. Router-Based Flow Aggregation Export (RBA).

Index.