A guide to building and modifying Tcl scripts to automate network administration tasks Streamline Cisco network administration and save time with Tcl scripting Cisco networking professionals are under relentless pressure to accomplish more, faster, and with fewer resources. The best way to meet this challenge is to automate mundane or repetitive tasks wherever possible. In this book, three Cisco experts show you how to use Tcl scripting for Cisco IOS devices to do just that. You’ll learn easy techniques for creating, using, and modifying Tcl scripts that run directly on Cisco network devices from the Cisco IOS command line. The authors first teach basic Tcl commands and concepts for capturing and manipulating data and for querying or controlling Cisco equipment. Building on these core skills, they show you how to write scripts that automate and streamline many common IOS configuration, monitoring, and problem-solving tasks. The authors walk through the entire script development process, including planning and flowcharting what you want to accomplish, formatting your code, adding comments, and troubleshooting script errors. They also present many downloadable sample scripts, along with practical guidance for adapting them to your own environment. Whatever your role in managing, monitoring, or securing Cisco IOS networks and equipment, this book will help you get the job done more rapidly and efficiently. Ray Blair, CCIE No. 7050, is a Cisco vertical solutions architect specializing in large network designs. He has more than 20 years of experience in designing, implementing, and maintaining networks, and maintains three CCIE certifications. Arvind Durai, CCIE No. 7016, Advanced Services Technical Leader for Cisco, specializes in supporting major Cisco enterprise customers in finance, manufacturing, e-commerce, government, and healthcare. He holds CCIEs in Routing and Switching, and in Security. John Lautmann, Cisco Software Engineer, has developed and enhanced network management software for twelve years, and holds six patents. He has helped develop new Cisco IOS features ranging from data link switching to IOS Tcl Interpeter and digitally signed Tcl scripts. Automate routine administration tasks you’ve always performed manually Instantly collect and modify IOS router configurations and other data Write Syslog scripts to document failures, monitor network health, collect statistics, and send alarm messages Implement automated network performance measurement using IP SLA Use the Embedded Event Manager’s event detectors, server, and policies to customize device operation Trigger preplanned actions to correct problems as they arise Simplify policy management using the Tcl script refresh feature Protect Tcl script security with digital signatures and PKI Understand how Tcl functions within the Cisco IOS environment Master Tcl syntax and commands through hands-on practice Learn best scripting practices through expert examples Quickly modify this book’s examples for your own environment This book is part of the Networking Technology Series from Cisco Press®, which offers networking professionals valuable information for constructing efficient networks, understanding new technologies, and building successful careers. Category: Networking Covers: Network Administration $60.00 USA / $72.00 CAN

Table of Contents:
Introduction xiv Chapter 1 The Origin of Tcl 1 Tcl and Cisco IOS Software 3 Embedded Event Manager and Tcl 4 Restriction of Tcl in IOS 4 Tcl with EEM Support in IOS 5 Using Tcl Scripts in the Network 8 Troubleshooting Problems 8 Monitoring the Network 8 Adding Intelligence to Cisco IOS Protocols 9 Summary 9 References 9 Chapter 2 Tcl Interpreter and Language Basics 11 Simple Variables in Tcl 12 Storing Variables 12 Viewing Variables 13 The append Command 13 The incr Command 13 Representation of Variables in Tcl 14 Command Substitution 14 Variable Substitution 15 Lists 17 lappend 18 lindex 18 linsert 18 llength 19 lsearch 19 lreplace 20 lrange 20 lsort 20 Procedures 21 for Command 22 foreach Command 23 while Command 23 Arrays 24 if Command 26 switch Command 27 Files 28 Summary 31 References 31 Chapter 3 Tcl Functioning in Cisco IOS 33 Understanding the Tcl Interpreter in Cisco IOS 33 Using Cisco IOS Exec-Mode Parser in the Tcl Shell 34 Entering an IOS Command into the Tcl Command Interpreter 35 Using Tcl to Enter Commands 36 Copying a Tcl Script to a Cisco IOS Device 38 Fetching a Cisco IOS Tcl Script from a Remote Device 41 Using Tcl to Examine the Cisco IOS Device Configuration 41 Using Tcl to Modify the Router Configuration 43 Using Tcl with SNMP to Check MIB Variables 44 Other Uses of SNMP 44 Enabling SNMP on a Cisco IOS Device 47 Querying the Configuration of a Cisco IOS Device Using SNMP 48 Modifying the Configuration of a Cisco IOS Device Using SNMP 51 Summary 53 References 53 Chapter 4 Embedded Event Manager (EEM) 55 EEM Architecture 55 Policies 56 EEM Server 56 Event Detectors 57 Software Release Support for EEM 60 Platform and IOS Considerations for EEM 65 Writing an EEM Applet 66 Practical Example of an Event Trigger 68 Using Object Tracking as an Event Trigger 69 Creating Applet Actions 70 Examples of EEM Applets 70 Configuring the IP SLA Sender and Responder 72 Applet and IP SLA Route Failover Example 74 Applet That Monitors the Default Route 83 Applet and Application Failover with a Network Address Translation Example 88 Using EEM and Tcl Scripts 96 Programming Policies with Tcl 97 Tcl Example Used to Check for Interface Errors 98 Tcl Example Used to Check the CPU Utilization 104 Summary 110 References 110 Chapter 5 Advanced Tcl Operation in Cisco IOS 111 Introduction to the Syslog Protocol 112 Configuring Syslog Server Parameters in Cisco IOS 113 Syslog Tcl Script Example 116 Syslog Tcl Script Sample Output 118 Sending Syslog Messages to a File 121 Syslog Server Script Procedures 124 Syslog Server Script Body 127 Putting the Syslog Script into Operation 129 Introduction to Embedded Syslog Manager 130 Filtering Syslog Messages 130 ESM Global Variables 134 Rebuilding a Syslog Message from Its Components 136 Displaying/Adding ESM Tcl Script Filters 137 Introduction to Embedded Menu Manager 139 Using Tcl as a Web Server 144 Obtaining a Free Web Server Application 147 Reverse Engineering the Web Server 149 Creating Your Own Simple Web Page 152 Creating a Web Page Using IOS show Commands 154 Adding User Input to the Web Page 157 Introduction to IP SLA 160 Adding the IP SLA Measurement to the Web Page 162 Modifying the Button and Label for User Input 162 Creating a Tcl Script to Display IP SLA Measurement Results 163 Putting the New Tcl Scripts into Operation 165 Reformatting the IP SLA Output for Readability 167 Automatic Removal and Creation of IP SLA Entries 170 Displaying the Results of the IP SLA Measurement with Auto-Refresh 174 Tcl Script Refresh Policy 177 SNMP Proxy Event Detector 178 Remote-Procedure Call Requests 179 Multiple-Event Support for Event Correlation 180 Using the clear Command 181 Summary 182 References 182 Chapter 6 Tcl Script Examples 183 Creating an Application from Start to Finish 183 Determine What You Want to Accomplish 183 Creating a Flowchart 184 Deciding What the User Interface Should Look Like 185 Write the Code in Pseudo-Code 187 Before You Begin 188 Starting to Program the Application 190 Configuring the Web Server 190 Writing Code for the MPLS VPN Script 191 Configuring HTML 209 Writing Code for the MPLS CFG Script 216 Troubleshooting as You Go 228 Using Tcl to Troubleshoot Network Problems 230 Monitoring the Console for Events 233 Creating a Web Application for Remote SNMP Graphing 236 Summary 241 References 241 Chapter 7 Security in Tcl Scripts 243 Introduction to PKI Infrastructure 243 PKI Prerequisite 244 Confidentiality with PKI 244 Digital Signatures with PKI 245 Using Digital Signatures to Sign a Tcl Script 247 Step 1: Decide on the Final Tcl Script Contents (Myscript) 248 Step 2: Generate a Public/Private Key Pair 248 Step 3: Generate a Certificate with the Key Pair 250 Step 4: Generate a Detached S/MIME pkcs7 Signature for Myscript Using the Private Key 250 Step 5: Modify the Format of the Signature to Match the Cisco Style for Signed Tcl Scripts and Append It to the End of Myscript 251 Tcl Script-Failure Scenario 256 Scaling Tcl Script Distribution 257 Summary 258 References 258 Appendix A Cisco IOS Tcl Commands Quick Reference 259 TOC, 9781587059452, 5/17/10