A guide to understanding the troubleshooting tools, commands, and methodologies that enable reliable performance for remote access services
- Gain a solid grasp of enterprise telecommunications technology fundamentals, including service options and clocking, line coding, and framing in carrier systems
- Understand how network traffic is handled by carriers and service providers
- Examine a layer-by-layer, systematic approach to troubleshooting issues
- Design, configure, and troubleshoot T1 and PRI circuits, text and PPP dial-in and dial-out services, and Cisco AS5000 Access Servers
- Design, configure, and troubleshoot ISDN BRI at the physical, data link, and network levels, as well as PPP, MMP, and telephone interfaces
- Design, configure, and troubleshoot Frame Relay UNI and NNI interfaces, with a focus on new installs, wrong DLCI, LMI settings, performance and multicast issues, and re-hosting of Frame Relay service
- Design, configure, and troubleshoot PTPP, L2TP, and IPSec VPNs, examining specific VPN clients, Internet technology, and LAN issues
- Resolve common availability issues for all major remote access technologies through real-world scenarios for dial, ISDN, Frame Relay, and VPNs
The ranks of telecommuters, remote employees, and mobile users are growing every day and their communications needs are expanding just as rapidly. Advancements in remote access technologies allow users to become less dependent on the office and to increase productivity without sacrificing the convenience of direct access to the corporate network. Convenient, secure, and reliable connections are crucial to corporate reliance on remote access. Customers, employees, and partners should connect seamlessly, as if they were in company headquarters. They also must count on the ability to log in and to remain connected at an expected level of performance. Understanding how to deploy remote access services is the first step to realizing the benefits that these services offer but inconsistent performance or denial of service threaten productivity gains. It is critical that these services not only be available but also perform as promised.
Troubleshooting Remote Access Networks helps you understand underlying technologies and gain insight into the challenges, issues, and best practices for supporting remote access networks. This book focuses on the enterprise portion of a remote access network and includes service provider troubleshooting and design information that helps both enterprise and service provider network engineers understand the larger picture of remote access networks. This book opens with a section covering fundamental concepts. Design issues, provisioning, DSL and cable connectivity options, central office operations, authentication techniques, and troubleshooting tools are all addressed in this part of the book, forming the foundation upon which later sections are built. Each of the subsequent four parts examines a key remote access technology, including dial, ISDN, Frame Relay, and VPNs. Each part is a self-contained tutorial, providing foundation review, design and configuration overviews, and troubleshooting techniques. Each part concludes with a series of real-world support scenarios that represent proven best practices for remote access network management, drawn from tens of thousands of cases handled by the Cisco Remote Access team.
Whether you are looking for a design, configuration, and support reference guide, or need a preparation tool to help you prepare for the CCIE exam, Troubleshooting Remote Access Networks provides you with expert-level solutions to help guarantee the availability of remote access services.
Table of Contents
(NOTE: Each chapter concludes with a Summary and Review Questions.)
I. REMOTE ACCESS FUNDAMENTALS.
1. Remote Access Overview.
Management Considerations. Defining the Remote Access User Population. Remote Access Service Options. VPN Service Vehicles. Provisioning of Enterprise Remote Access Services.
2. Telecommunication Basics.
Shannons Capacity Theorem. Modulation and Line-Coding Techniques in Wired Networks. Modulation and Line-Coding Techniques in Wireless LANs. Modulation and Line-Coding Techniques in Hybrid Networks. Clocking, Line Coding, and Framing in Carrier Systems. End Notes.
3. The Cloud.
Carriers, Service Providers, and How Traffic Is Carried. FDM. Digitalization of the Signal and Pulse Code Modulation. TDM. T-Carriers. SONET, Synchronous Transport Signal, and Synchronous Digital Hierarchy. Carriers Facilities and Switching Systems. ISPs and ASPs. Data Centers and Internet Hosting Services. The Future of Service Providers. End Note.
4. Troubleshooting Approaches, Models, and Tools.
Interconnection Models. Troubleshooting Models and the Baseline. Common and Cisco-Specific Tools. End Notes.
5. Dial Technology Background.
Overview of Modems. Telco Issues. Authentication Options. PPP. End Notes.
6. Dial Design and Configuration Solutions.
Dial Design Solutions. Dial Configuration Solutions.
7. Dial Troubleshooting.
Troubleshooting NAS WAN Links. Troubleshooting Dial-In Service. Troubleshooting Dial-Out Service. AS5x00 Specific Commands and Debugs.
8. Dial Troubleshooting Scenarios.
Scenario 1: Authentication Time Outs—Part I. Scenario 2: Authentication Time Outs—Part II. Scenario 3: Frequent Retrains and Disconnects. Scenario 4: Dirty Phone Line. Scenario 5: Bad Modem. Frequently Asked Questions and Answers.
9. ISDN Technology Background.
ISDN Standards. ISDN Channels. ISDN Planes: ISDN Layer Architecture. ISDN Switch Types.
10. ISDN Design Solutions.
Enterprise and ISP Designs. IP Pool Design. NAT and PAT. Per-User (Per Function) Configuration. MLP. MMP.
11. Cisco ISDN Configuration Solutions.
Cisco ISDN Cost-Effective Solutions. ISDN Security. Configuring the POTS (Telephone) Interfaces.
12. ISDN BRI Troubleshooting.
Troubleshooting the Physical Layer. Troubleshooting the Data Link Layer. Troubleshooting the Network Layer. Troubleshooting PPP. Troubleshooting Telephone Interfaces. End Notes.
13. Troubleshooting Scenarios for ISDN BRI.
Recommendations for Practical Troubleshooting of ISDN Remote Services. Scenario 1: New Install Problems. Scenario 2: Dial-Out Problems. Scenario 3: ISDN Performance Problems. Scenario 4: End-to-End Communication Problems. Scenario 5: Windows 2000 DDR Issue.
IV. FRAME RELAY.
14. Frame Relay Technology Background.
Frame Relay Standards. Frame Relay Service Architecture. Frame Relay Protocols. End Notes.
15. Frame Relay Design Solutions.
Design Parameters. Frame Relay Topologies and Congestion Control. Frame Relay and Upper-Layer Protocols. LMI. Address Resolution: ARP, Reverse ARP, and Inverse ARP. End Notes.
16. Basic and Advanced Frame Relay Configurations.
Basic Frame Relay Configurations. Advanced Frame Relay Configurations.
17. Frame Relay Troubleshooting.
Beginning the Frame Relay Troubleshooting Process. Physical Layer Troubleshooting. Data Link Layer Troubleshooting. Performance Problems. End Notes.
18. Frame Relay Troubleshooting Scenarios.
Scenario 1: New Install Issues. Scenario 2: Mismatched DLCI Settings. Scenario 3: Performance Issues from Flapping Lines and Traffic Shaping Issues. Scenario 4: IP Multicast Issues in Frame Relay. Scenario 5: Frame Relay Host Migration.
19. VPN Technology Background.
Service Provider, Dedicated, and Access VPNs. Enterprise VPNs Overview. Enterprise VPN Categories. Network Layer (Layer 3) VPNs. End Notes.
20. Remote Access VPN Design and Configuration Solutions.
Remote Access VPN Design Solutions. VPN Configuration Considerations. End Notes.
21. Remote Access VPN Troubleshooting.
Troubleshooting Cisco Remote Access VPN Clients. Internet Technologies and Remote Access VPNs. LAN and General Networking Issues Affecting Remote Access VPNs. End Notes.
22. Remote Access VPN Troubleshooting Scenarios.
Warming Up with Preliminary Troubleshooting Steps. Scenario 1: Cannot Authenticate. Scenario 2: Can Authenticate but Problems Passing Data. Scenario 3: PPPoE Software/Hardware Problems. Scenario 4: 3002 Connection Problems. Scenario 5: Extranet Issues. Summary.
Appendix A. Answers to Review Questions.