Chapter 13 Network Troubleshooting Introduction Look at Avoiding

Chapter 13 Network Troubleshooting

Introduction • Look at: – Avoiding Potential Problems (13. 1) – Principles of Troubleshooting (13. 2) – Accessing Key Information Resources (13. 3) – Handling Common Sources of Trouble (13. 4)

Avoiding Potential Problems • There are two approaches to trouble shooting: – preventing potential problems through proper planning – quickly fixing what fails • The former is often referred to as trouble avoidance or pre-emptive troubleshooting • The later is referred to as troubleshooting or damage control

Avoiding Potential Problems • To be effective, both should be used in combination • Be proactive in managing the environment • Know how to effectively troubleshoot any issue • Documentation is important • It's a tedious job but it is imperative that you have proper documentation

Avoiding Potential Problems • Ensure that users have ongoing access by making sure that if something happens you have a backup plan: – Identify the data that should be backed up – Determine the backup type and schedule – Designate someone to be responsible – Be sure the tapes are properly labeled – Keep a log

Avoiding Potential Problems • Security policy should detail hardware and software along with some of these areas: – Clear paths of responsibility and user expectations – Awareness of privacy issues that may arise – A separation of duties, so that total control is not left in the hands of a single individual

Avoiding Potential Problems • Security policy should detail hardware and software along with some of these areas: – Password length, duration, history, and complexity requirements – A clear policy for the destruction of data – Procedures for creating and authorizing accounts – Incident response and disaster recovery planning policies

Avoiding Potential Problems • The goal of security is expressed in terms of: – Confidentiality – Integrity – Availability • These goals can be achieved through creating hardware and software standards

Avoiding Potential Problems • Workstation consistency is often overlooked: – Installing unauthorized software – Downloading infected music and movie files – Opening an e-mail message that contain a virus – Using weak passwords – Not logging off the network when leaving the building

Avoiding Potential Problems • Standards for laptops, personal digital assistants (PDAs), Palm Pilots, and Pocket PCs may be more difficult to define • If these devices are company issued or company supported, they must be standardized as well • These devices are susceptible to theft because they are small and valuable. • Many times contain important information about the company

Avoiding Potential Problems • You must also define and document standards for new server installations along with guidelines for current server configurations • The configuration process should start with installing only the services necessary for the server to function • Limit physical access to the server • Use Redundant Array of Inexpensive Disk (RAID), uninterruptible power supply (UPS) equipment, and clustering

Avoiding Potential Problems • Policies should include provisions for change authorization, documentation, and notification • Include procedures to be used when hardware, software, or storage media is replaced or discarded • Planning and testing can eliminate corruption or data deletion problems • Sufficient time must be spent to ensure that the transition goes as smoothly as possible

Avoiding Potential Problems • The following should be considered when creating a change in management policy: – Establish a schedule for changes – Make sure users are notified of the changes – Conduct proper testing • Changes should be scheduled during off hours

Avoiding Potential Problems • Documentation is critical • Before actually deploying the change, testing should be conducted • Testing should be well documented • A rollback strategy should be part of every change plan

Avoiding Potential Problems • Thorough documentation is a necessary part of an administrator's job • Document everything you do and be as detailed as you can • Documenting is particularly important because of the impact it can have on business if legal action is involved • All documents should be kept in both hardand soft-copy form

Avoiding Potential Problems • Your network documentation should include these components: – Policies and procedures – Network history – Network map – Cable diagrams and layouts – Contact list – Equipment list

Avoiding Potential Problems • Your network documentation should include these components: – Computer and network device configuration – Software and its configuration – Network address list – Software licensing information

Avoiding Potential Problems • Pre-emptive troubleshooting is also called trouble avoidance • It will save time and may help save data when problems arise • Pre-emptive troubleshooting can also prevent additional expense and downtime while trying to figure out what happened after a failure

Avoiding Potential Problems • The ISO defines five pre-emptive troubleshooting network management categories: – Accounting management – Configuration management – Fault management – Performance management – Security management

Avoiding Potential Problems • The measure of normal network activity is known as a baseline • This gives you a point of reference when the network goes awry • Baselining should be done for both network and application processes • The allows you to determine whether you have a hardware or software issue

Avoiding Potential Problems • There are tools can be used to gather network information • Event Viewer allows you to audit certain events • Task manager can be used to end processes or applications that get hung up without having to reboot the machine • Auditing is the process of tracking users and their actions on the network

Avoiding Potential Problems • Keep in mind that auditing uses system resources and space • The Performance console is used for tracking and viewing the utilization of operating system resources • A network monitor can be used to capture network traffic and generate statistics for creating reports

Principles of Troubleshooting • Troubleshooting requires skill • These skills are acquired through experimentation and experience • You cannot learn the resolution to every problem that exists • You can, however, learn a methodology to find and diagnose nearly every problem in a systematic and logical manner

Principles of Troubleshooting • The following are the most common network problems: – User error – Physical connections – System needs a reboot • If these steps don't help, then it's time to move on and try other troubleshooting options

Principles of Troubleshooting • Research on problem solving and reasoning is fundamental to understanding troubleshooting skills • You can choose from several different methodologies of troubleshooting • These give us guidelines for logical solving problems using a step-by-step process

Principles of Troubleshooting • The first step is to determine the scope of the problem by identifying the symptoms • The next step is to collect specific information about the problem at hand • Once you have the pertinent information, then the scope is determined • Begin to isolate the problem by testing each of the causes, starting with the most obvious first

Principles of Troubleshooting • • • Attempt to re-create the problem Make only one change at a time Test each change Don't be afraid to ask for help Read the documentation that came with the hardware or software • Don't forget about the obvious

Principles of Troubleshooting • Creating a Hardware Toolkit: – Crossover cable – Hardware loopback adapter – Tone generator – Cable tester or cable checker – Voltmeters – Time domain reflectometer (TDR) – Oscilloscope

Principles of Troubleshooting • Creating a Software Toolkit: – Ping – Netstat – Nbtstat – Traceroute – Network monitors – Protocol analyzer

Accessing Key Information Resources • One of the best places for troubleshooting a problem is the manufacturer's Web site • Subscription services such as Tech. Net can be used to obtain a wealth of information • Vendor-provided CDs should be one of the first places you go to look for information • Look at the readme. txt file even before the product is installed

Accessing Key Information Resources • Resource kits are another excellent source of information about your operating system • Call the vendor and open up a technical support incident to solve the problem • If it is a known issue the vendor may have documented fixes available

Accessing Key Information Resources • Have the following information ready to assist the support department: – The operating system you are running – Service packs that are installed – Version numbers of hardware and software – Serial numbers – Detailed account of the problem and troubleshooting steps you have taken

Accessing Key Information Resources • Other excellent sources of information are periodicals and white papers • Many new magazines and periodicals are introduced each year, some of them deal with specific computing environments • Besides white papers and periodicals, don’t forget to keep a couple of good reference books handy, especially when you first start out

Handling Common Sources of Trouble • Not all problems will be easy to fix • The two most common causes for data not moving reliably are: – A physical connection breaks such as the cable being unplugged or broken – A network device is not working properly

Handling Common Sources of Trouble • The majority of networking problems occur at the Physical layer of the OSI model and include problems with: – cables – connectors – NICs • Check cabling and connections first during your network troubleshooting process

Handling Common Sources of Trouble • Power problems will crop up in various ways • One of the most obvious is when power strips are daisy chained together • The devices will not get enough power • The other end of the spectrum is that this will occasionally trip the circuit breakers or start a fire

Handling Common Sources of Trouble • Power not properly conditioned, can have devastating effects on equipment : – Noise – Spikes – Surges and overvoltages – Sags and brownouts – Blackouts

Handling Common Sources of Trouble • Always connect your sensitive electronic equipment to: – power conditioners – surge protectors – for the best protection an uninterruptible power supply (UPS) • The UPS powers the computer so that you can take action without data loss

Handling Common Sources of Trouble • There are basically three different types of devices that are classified as UPSs: – Standby power supply (SPS) – Hybrid or ferroresonant UPS systems – Continuous UPS • Never plug a printer into a UPS • Power problems cannot be eliminated but the damage can be minimized or prevented

Handling Common Sources of Trouble • A software upgrade can cause issues on the system even though you tested the upgrade • You should be prepared to rollback or reverse the process. • This process is also referred to as backleveling • Most often the best source of help when a problem occurs is the manufacturer's documentation

Handling Common Sources of Trouble • You will also have to provide for a backup plan in the event a hardware upgrade doesn't go as planned • It is important not the discard the old device in the event the upgrade causes issues • This applies to the drivers that may be necessary as well

Handling Common Sources of Trouble • The complexity of network topology and communication equipment has become more and more sophisticated • Performance management as well as response time management is more difficult • Sometimes you will find that for an unknown reason the network performance begins to suffer

Handling Common Sources of Trouble • Here are some avenues for you to consider when there are issues with performance: – Change is the biggest factor that can cause poor network performance – Another big factor that affects network performance is playing games or downloading music and movie files

Handling Common Sources of Trouble • Here are some avenues for you to consider when there are issues with performance: – Sometimes applications have memory leaks or a new version may be bloated or have an improperly programmed query function – Adding new electrical equipment may have a negative effect on the network

Handling Common Sources of Trouble • Here are some avenues for you to consider when there are issues with performance: – Adding new hardware such as additional servers or workstations may cause performance to decrease – Other changes in workload or workplace behavior, including adding more users, could affect performance