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Chapter 2:TroubleshootingTroubleshooting Processes for Complex Enterprise Networks
CCNP TSHOOT: Maintaining and Troubleshooting IP NetworksCCNP TSHOOT: Maintaining and Troubleshooting IP Networks
© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco PublicCourse v6 Chapter #
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Chapter 2 Objectives
Identify troubleshooting principles and evaluate troubleshooting methodologies. Plan and implement troubleshooting procedures as part of a
structured troubleshooting methodology.Pl d i l t t bl h ti d t k Plan and implement troubleshooting and network maintenance procedures to effectively support each other.
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Troubleshooting MethodologiesFlow chart of a structured troubleshooting approach
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Troubleshooting MethodologiesShoot from the hip vs. structured troubleshooting method
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Troubleshooting Approaches
Top-down Bottom-upBottom up Divide and conquer Follow-the-path Spot the differences Move the problem
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Troubleshooting Approaches - Spot the Differences ExampleDifferences Example
Branch1 is in good working orderBranch1# show ip route<output omitted>
10.0.0.0/24 is subnetted, 1 subnetsC 10 132 125 0 is directly connected FastEthernet4C 10.132.125.0 is directly connected, FastEthernet4C 192.168.36.0/24 is directly connected, BVI1S* 0.0.0.0/0 [254/0] via 10.132.125.1
Branch2 has connectivity problems Branch2# show ip route<output omitted><output omitted>
10.0.0.0/24 is subnetted, 1 subnetsC 10.132.126.0 is directly connected, FastEthernet4C 192.168.37.0/24 is directly connected, BVI1
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Troubleshooting Approaches - Move the Problem ExampleProblem ExampleLaptop B is having network problems. Cable or port swapping can help isolate the problem.
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Implementing Troubleshooting Procedures
Defining the problem Gathering informationGathering information Analyzing the information Eliminating possible problem causes Formulating a hypothesis about the likely cause of the
problemT ti th t h th i Testing that hypothesis Solving the problem
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The Troubleshooting Process – Verify and Define the ProblemDefine the Problem
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The Troubleshooting Process – Gather InformationInformation
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The Troubleshooting Process – Analyze
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The Troubleshooting Process – Eliminate
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The Troubleshooting Process – Propose HypothesisHypothesis
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The Troubleshooting Process – Test HypothesisHypothesis
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The Troubleshooting Process – Solve Problem
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The Troubleshooting and Network Maintenance
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The Troubleshooting and Network Maintenance Cont– Cont.
Accurate documentation is critical to effective troubleshooting. A network baseline is essential and can include:
• Interface load for critical network links (IOS)CPU l d d f t d it h (SNMP)• CPU load and memory usage of routers and switches (SNMP)
• Accounting of network traffic (NBAR, NetFlow)• Measurement of network performance characteristics (IP SLA)( )
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Communication and Change ControlCommunication plays a role in all phases of structured troubleshooting.
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Communication and Change Control – Cont.
Change control is a fundamental process in network maintenance. Controls when changes are made, authorization required and what
actions are taken. Can reduce unplanned outages and increase network uptime. The change control process:g p
• Implement the change• Verify that it achieved the desired results• Roll back if necessary• Roll back if necessary • Back up the changed configurations or software• Document/communicate your changes
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Disaster Recovery Tools
Successful disaster recovery is dependent on the existence of the following: • Up to date configuration backups• Up to date software backups• Up to date hardware inventories and documentation• Up to date hardware inventories and documentation• Configuration and software provisioning tools
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Chapter 2 Summary
The fundamental elements of a troubleshooting process:• Gathering of information and symptoms• Analyzing information• Eliminating possible causes • Formulating a hypothesisg yp• Testing the hypothesis Some commonly used troubleshooting approaches are:
• Top down• Top-down• Bottom-up• Divide-and-conquer
F ll th th• Follow-the-path • Spot the differences• Move the problem
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Chapter 2 Summary – Cont.
Useful data to gather and create a network baseline are:• Basic performance statistics using show commands• Accounting of network traffic using RMON, NBAR, or NetFlow statistics• Measurements of network performance characteristics using the IP SLA
feature in IOS
Communication is an essential part of the troubleshooting process and happens in all stages of troubleshooting:• Report the problem• Report the problem• Gather information• Analyze and eliminate possible causes• Propose and test a hypothesis• Solve the problem
Change control is one of the most fundamental processes in
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g pnetwork maintenance.
Chapter 2 Labs
There are no labs for this chapter.
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