Troubleshooting and Maintaining Cisco IP Networks

So you have completed your CCNP Route and Switch exams. This is the last exam required to achieve CCNP status. The exam is 150 minutes. The code for the exam is 642-832 TSHOOT. It tests your skill in all areas of routing and switching, which you need to know because those skills apply to all exams. Unlike other exams, Cisco helped candidates by giving them the diagram for the exam. This gives candidates the opportunity to practice with the topology beforehand. This test can be challenging as almost all the scenarios have similar questions.

We only need to identify each problem without having to make the correct configuration. But you have to answer three types of questions:

  • * Which device causes a problem
  • * Which technology is used
  • * How to fix it

Exam Structure:

  • * About 3 multiple choice questions
  • * Two drag and drop Questions

  • Thirteen lab-simulation questions with the same network topology (13 troubleshooting tickets or you can call it one “big” question). Each lab-simulation is called a ticket and you can solve them in any order you like.

The exam tests a candidate on how to:

Maintain and monitor network performance

  • * Develop a plan to monitor and manage a network
  • * Perform network monitoring using IOS tools
  • * Perform routine IOS device maintenance
  • * Isolate sub-optimal internetwork operation at the correctly defined OSI Model layer

Troubleshoot Multi-Protocol system networks

  • * Troubleshoot EIGRP
  • * Troubleshoot OSPF
  • * Troubleshoot eBGP
  • * Troubleshoot routing redistribution solution
  • * Troubleshoot a DHCP client and server solution
  • * Troubleshoot NAT
  • * Troubleshoot first hop redundancy protocols
  • * Troubleshoot IPv6 routing
  • * Troubleshoot IPv6 and IPv4 interoperability
  • * Troubleshoot switch-to-switch connectivity for the VLAN-based solution
  • * Troubleshoot loop prevention for the VLAN-based solution
  • * Troubleshoot access ports for the VLAN-based solution
  • * Troubleshoot private VLANS
  • * Troubleshoot port security
  • * Troubleshoot general switch security
  • * Troubleshoot VACLs and PACLs
  • * Troubleshoot switch virtual interfaces (SVIs)
  • * Troubleshoot switch supervisor redundancy
  • * Troubleshoot switch support of advanced services (i.e., Wireless, VOIP and Video)
  • * Troubleshoot a VoIP support solution
  • * Troubleshoot a video support solution
  • * Troubleshoot Layer 3 Security
  • * Troubleshoot issues related to ACLs used to secure access to Cisco routers
  • * Troubleshoot configuration issues related to accessing the AAA server for authentication purposes
  • * Troubleshoot security issues related to IOS services (i.e. Finger, NTP, HTTP, FTP, RCP etc.)


The exam is unlike other Cisco exams, as you will be left to just one screen with the tickets listed. Unlike other exams, you can go back, but the moment you click “done,” you can’t go back. The tickets are listed from 1 – 13. You can start from any ticket. You are given the scenario, Layer 2 topology and the IPv4 layer3 topology.

Key points for test takers

There are a couple of commands that are very essential for the exam and in the real world during troubleshooting. I will list a couple of them below

Important “Show” Cisco Commands

When it comes to identifying hardware problems or service malfunctions, you need to know the basic Cisco commands to use in order to diagnose the problem. Moreover, these are the commands that Cisco experts would ask from you in case you have a maintenance agreement with them, so it is necessary to know them.

When suffering from performance degradation, the following commands are the first to consider:

  • * Show interfaces
  • * Show buffers
  • * Show processes cpu
  • * Show memory

When you come across IP protocol errors or connectivity errors, the outputs from the following commands need to be evaluated:

  • * Show IP protocol
  • * Show IP route
  • * Show IP interfaces
  • * Show IP access-lists
  • * Show IP traffic

There is a single Cisco command that collects a lot of information equivalent to issuing many “show” commands. I am talking about the “show tech-support” command.

There is another crucial command and that is the “show version” command. This command provides the following important information:

  • * The installed IOS number and name.
  • * The system’s Bootstrap and installed Boot Loader.
  • * The system’s uptime.
  • * The reason for the latest system’s restart.
  • * The date of the last restart.
  • * The image filename and stored location.
  • * Hardware information such as processor type, memory usage, controllers, DSPs, etc.
  • * The value of the configuration register.

The Show IP Interface Command

The “show ip interface” command will provide details regarding layer 3 configuration on the interfaces. Using this command you can see the IP address and mask configured on a given interface, whether an access list is applied on the interface as well as basic
IP information.

The Show IP Route Command

Use the “show ip route” command to find detailed information regarding the routes configured on the router. Keep in mind that the router can only route packets to the networks listed in its routing table. It is possible that a router cannot reach a network you manually configured therefore, that specific route is removed from its table. That is why you should use the “show running configuration” command in conjunction with “show IP route” to spot possible inconsistencies.

Show Running-Config and Show Startup-Config Commands

Issue the “show running configuration” command to find out the whole configuration your Cisco devices use while operating. This is one of the strongest commands any networking engineer should know. By looking at the details of your devices, configuration can help you identify the cause to your problem. Use the “show startup configuration” command to see the configuration commands that will be loaded to your device the next time it reboots and compare it with your running configuration in order to identify possible unconformities.

References

http://www.trainsignal.com/blog/cisco-troubleshooting-tools
http://www.cisco.com/web/learning/exams/list/tshoot.html#~Oview
http://www.cisco.com/web/learning/le3/le2/le37/le10/tshoot_demo.html
https://learningnetwork.cisco.com/docs/DOC-6738