Hands-on Networking Fundamentals. Chapter 12 Maintaining and Troubleshooting Your Network

Transcription

1 Hands-on Networking Fundamentals Chapter 12 Maintaining and Troubleshooting Your Network

2 Objectives Use hardware and software methods to monitor a network Perform backups over a network Solve a broad range of network problems Design a solutions strategy for network troubleshooting Hands-on Networking Fundamentals 2

3 How to Monitor Your Network Monitor network regularly after installation Two-fold purpose for monitoring networks Become familiar with your network Quickly locate and troubleshoot problems Monitoring tools to be presented Network-monitoring devices Basic network-monitoring tools in operating systems System Monitor Network Monitor SNMP service Hands-on Networking Fundamentals 3

4 Network-Monitoring Devices Range from voltage testers to protocol analyzers Price is directly proportional to functionality Examples of test and monitoring devices Voltmeter, multimeter, and optical power meter Cable scanner MAU analyzer Time domain reflectometer Wireless testing tool Protocol analyzer Hands-on Networking Fundamentals 4

5 Voltmeters, Multimeters, and Optical Power Meters Voltmeter used to test two physical properties Voltage on a network cable Signal strength on any network device Multimeter: voltmeter and ohm meter combination Voltmeter tests voltage and signal strength Ohm meter tests for cable resistance Optical power meter Measures light signal strength on fiber-optic cable Should be handled by optical cable expert Hands-on Networking Fundamentals 5

6 Cable Continuity Tester Determines if signal passes from end to end Enables you to check for openings or breaks Some versions test integrity of cable pairs Example: test for shorted or crossed pairs As applied to fiber-optic cables Tests whether light impulse can traverse cable Hands-on Networking Fundamentals 6

7 Cable Scanner Also called cable testers or cable performance testers Tests for length and other characteristics of cable How to test the cable Connector on cable section attached to scanner Scanner measures cable by transmitting signal Signal is timed to determine where it stops Time and signal speed data used to derive distance Open and short circuits detected by scanner Distance to problem output to LCD display or printer Many scanners also report RFI or EMI interference Hands-on Networking Fundamentals 7

8 Activity 12-1: Using a Cable Scanner Time Required: 10 minutes Objective: Learn to use a cable scanner. Description: If a cable scanner for twisted-pair cable is available to you, try this activity to measure the cable distance on a small network. You need access to a network that is not in use by others or you need to make your own network. If you make your own, connect two workstations to a switch by using UTP cable and make sure the switch is connected to power. Hands-on Networking Fundamentals 8

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10 MAU Analyzer Used on token ring networks Functions like a cable scanner Generates signal to measure cable distances Locates opens, shorts, faulty cable connections Determines if MAU is functioning properly Hands-on Networking Fundamentals 10

11 Time Domain Reflectometer TDR: has cable scanner functions plus more options Monitors line impedance, open, shorts, RFI/EMI, cable distances, connector and terminator problems How a TDR works Transmits signal that is reflected back Information gathered from returning signal Wave pattern duplicated to show data Enhanced TDR has memory feature Captures snapshots at different times Tracks sporadic problems or those due to interference Optical TDR available for fiber-optic cable Hands-on Networking Fundamentals 11

12 Wireless Testing Tool Determines performance characteristics of wireless network Moves through cells to test for problems Diagnostic examples Determines if access point is working properly Determines noise and signal loss Hands-on Networking Fundamentals 12

13 Protocol Analyzer Captures protocol and OSI layer information Operates in promiscuous mode Picks up and reads any frame or packet Analysis at first three OSI layers Physical: detects opens, shorts, electrical interference Data Link: detects data errors, such as bottlenecks Network: monitors routing information in packets Allows analysis of distance traveled by packets Some protocol analyzers examine upper OSI layers Specialized software used to interpret protocols Hands-on Networking Fundamentals 13

14 Activity 12-2: Protocol Analyzers Time Required: 15 minutes Objective: Learn about protocol analyzers from different vendors. Description: In this activity, you use the Internet to find out about protocol analyzers available from two different vendors. Hands-on Networking Fundamentals 14

15 Using Basic Network-Monitoring Tools in Your Operating System Cable-testing device not always needed Basic information provided by operating system Status of network connection Statistics of network performance Presentation of basic tools to follow Hands-on Networking Fundamentals 15

16 Using the Windows Connection Status Dialog Box A number of tasks that may be performed Verify connection of computer and its network segment Determine duration of the computer s connection View the connection speed Determine the number of bytes sent and received Determine the IP address information View the strength and status of a wireless connection Repair a connection Tool may be used on any network connection Examples: local area, wireless, and DSL connections Hands-on Networking Fundamentals 16

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18 Activity 12-3: Using the Connection Status Dialog Box Time Required: 10 minutes Objective: Use the Connection Status dialog box to verify the network connection in Windows XP and Windows Server Description: Sometimes you need a fast way to verify a computer s connection and the segment to which it is attached. In this activity, you use the Connection Status dialog box in Windows XP and Windows Server 2003 to verify a connection. Log on to an account with Administrator privileges for this activity. Hands-on Networking Fundamentals 18

19 Using ping to Test a Network Connection Typical uses for ping utility Testing the connection at the host computer Testing the connection of a target computer Testing connectivity between segments or networks Testing access over a WAN connection Testing to determine if a particular server is running Testing time for ping signal to make a round trip Example: CFO cannot access shared folder ping tests path from CFO node to marketing node Successful ping shows problem not connection related Hands-on Networking Fundamentals 19

20 Activity 12-4: Using ping in Windows XP and Windows Server 2003 Time Required: 5 minutes Objective: Test a Windows XP or Windows Server 2003 connection using ping. Description: Use the ping utility to test a network connection through Windows XP or Windows Server Log on using your own account. You need a computer that is connected to a LAN or to the Internet. Obtain the IP address of another computer on the LAN, or use your own IP address. If you have an Internet connection, ping a Web site. Hands-on Networking Fundamentals 20

21 Activity 12-5: Using ping in UNIX/Linux Time Required: 5 minutes Objective: Test a UNIX/Linux connection using ping. Description: In this activity, you use the ping utility to test a network connection on a computer running Fedora or Red Hat Enterprise Linux. Log in to your own account. Hands-on Networking Fundamentals 21

22 Using traceroute to Test a Network Connection Supported by Windows and UNIX/Linux systems Enter tracert command in Windows console Enter traceroute in UNIX/Linux systems Data returned by traceroute communication Number of hops between two nodes Nodes through which signal goes to reach destination Time for signal to reach destination Whether firewall is secure (should stop before firewall) Employs UDP and ICMP (Internet Control Message Protocol) Hands-on Networking Fundamentals 22

23 Activity 12-6: Using tracert in Windows XP and Windows Server 2003 Time Required: 5 minutes Objective: Determine the number of hops between two nodes using tracert. Description: In this activity, you use the Windows tracert utility to test a network connection and determine the number of hops between two computers. Hands-on Networking Fundamentals 23

24 Activity 12-7: Using traceroute in UNIX/Linux Time Required: 5 minutes Objective: Determine the number of hops between two nodes using traceroute. Description: In this activity, you use the UNIX/Linux traceroute command to test a network connection and determine the number of hops between two nodes. Hands-on Networking Fundamentals 24

25 Using netstat Purpose: gather data about TCP/IP communications Available in Windows and UNIX/Linux systems Communication information that may be viewed Protocol communications through TCP and UDP Network connections established by host computer TCP and UDP ports in use Routing table information Information about computers remotely logged onto host Multicast participation Data and communication errors Switches enable you to view specific network data Hands-on Networking Fundamentals 25

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29 Activity 12-8: Using netstat in Windows XP and Windows Server 2003 Time Required: 10 minutes Objective: Use netstat to gather network performance statistics in Windows XP and Windows Server Description: Through a range of switches, netstat offers many ways to view network performance statistics. In this activity, you use netstat to monitor a network through Windows XP and Windows Server Hands-on Networking Fundamentals 29

30 Activity 12-9: Using netstat in UNIX/Linux Time Required: 10 minutes Objective: Use netstat to gather network performance statistics in UNIX/Linux. Description: The way in which netstat statistics are displayed varies a little between Windows and UNIX/Linux systems. In this activity, you use netstat in Fedora or Red Hat Enterprise Linux. Hands-on Networking Fundamentals 30

31 Using nslookup Domain Name Services (DNS) is a TCP/IP service nslookup available in Windows and UNIX/Linux Some DNS questions can be answered by nslookup Actions performed with nslookup Verifying that a DNS server is online and working Determining host name of a device if IP address known Determining the IP address if host name known Determining the primary DNS server on a network Querying the DNS database for information Typical use of nslookup command Determines if ftp.gnu.org FTP site is working Hands-on Networking Fundamentals 31

32 Using System Monitor in Windows Server Monitor hard disks, memory, and the processor Also monitor network performance and protocols Example 1: monitor network interface on server Track the number of bytes or packets received Example 2: monitor IPv4 traffic Assess number of datagrams or fragmented packets Hands-on Networking Fundamentals 32

33 Capturing Data Using System Monitor System Monitor located in Performance MMC Default view is in graph mode Begin analysis by selecting object(s) to monitor One or more counters associated with object Counter measures quantity of object in some unit Example: TCPv4 counter tracks Segments Sent/Sec Instance exists with different elements to monitor Example: when two or more NICs exist Add Counters Dialog box Used to select objects to monitor, counters, instances Click Add button above tracking Window to open Hands-on Networking Fundamentals 33

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35 Capturing Data Using System Monitor (continued) Three views to use when monitoring objects Graph: running line chart of the object Histogram: running bar chart Report mode: enables you to capture data for report Options set from buttons above tracking window Each object and counter combination in unique color Click on counter for status information Example: diagnosing cause of slow server access Often looks like slow response from network Real problem may be due to server overload Hands-on Networking Fundamentals 35

36 Activity 12-10: Exploring System Monitor Time Required: 15 minutes Objective: Use System Monitor to gather network performance statistics in Windows Server Description: This activity gives you an opportunity to practice viewing objects and counters in System Monitor in Windows Server Log on using an account with Administrator privileges. Hands-on Networking Fundamentals 36

37 Activity 12-11: Monitoring for Network and Processor Problems Time Required: 15 minutes or more Objective: Learn how to monitor for network and processor bottlenecks. Description: In this activity, you use System Monitor in Windows Server 2003 to monitor for a network bottleneck or a processor bottleneck. Hands-on Networking Fundamentals 37

38 Using Network Monitor Monitors network activity Captures frames and packets Hands-on Networking Fundamentals 38

39 Installing Network Monitor Two main steps Installing the Network Monitor Windows component Use Add or Remove Programs option in Control Panel Installing Network Monitor Driver Use Network Connections option in Control Panel Network Monitor Captures and distills network performance information Network Monitor Driver Protocol enables NIC to collect performance statistics Hands-on Networking Fundamentals 39

40 Activity 12-12: Installing the Network Monitor Windows Component Time Required: 10 minutes or fewer Objective: Learn how to install Network Monitor. Description: This activity enables you to install Network Monitor in Windows Server Log on using an account that has Administrator privileges. Hands-on Networking Fundamentals 40

41 Activity 12-13: Verifying the Installation of Network Monitor Driver Time Required: 5 minutes or fewer Objective: Verify that Network Monitor Driver is installed. Description: When you install Network Monitor, Network Monitor Driver is automatically installed as a protocol. In this activity, you verify that Network Monitor Driver is installed, and you learn how to reinstall it if it is removed. Log on using an account that has Administrator privileges. Hands-on Networking Fundamentals 41

42 Using Network Monitor to Capture Data Data detected and captured by Network Monitor Driver Packets or frames moving through NIC or WNIC Network Monitor analyzes raw data Network Monitor converts analysis into reports Information tracked (list not inclusive) Percent network utilization Frames and bytes transported per second Transmissions per second NIC statistics Addresses of network stations Hands-on Networking Fundamentals 42

43 Activity 12-14: Using Network Monitor Time Required: 15 minutes Objective: Learn how to use Network Monitor. Description: In this activity, you start Network Monitor and capture live network data for analysis. Log on using an account that has Administrator privileges. Hands-on Networking Fundamentals 43

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45 Using a Filter in Network Monitor Network Monitor supports event management Server administrator sets up filters Filters capture certain event or type of network activity Example: IP activity related to Internet traffic into server Frames/packets filtered on basis of two property types Service Access Point (SAP) Specifies process that accepts frame at destination Ethertype (ETYPE) Frame property including 2-byte code for protocol type Used in Ethernet communications by some vendors Hands-on Networking Fundamentals 45

46 Activity 12-15: Configuring a Filter in Network Monitor Time Required: 15 minutes Objective: Learn how to set up a filter in Network Monitor. Description: Assume that your network has an older NetWare server that runs a database application, which uses NetWare s Service Advertising Protocol (SAP). Create a filter to monitor only NetWare SAP frames that are received and sent by the NetWare server to determine if they are creating excessive network traffic. Hands-on Networking Fundamentals 46

47 Using the SNMP Service in Windows Server Perform tasks with agents and management systems SNMP agent responds to system's information request Systems and agents can be grouped into communities Management tasks performed Configuring network devices Monitoring the performance of a network Locating network problems Monitoring network usage Several operating systems/components use SNMP Examples: Windows Servers, DHCP servers Hands-on Networking Fundamentals 47

48 Activity 12-16: Installing the SNMP Service in Windows Server Time Required: 10 minutes Objective: Install SNMP in Windows Server Description: In this activity, you install the SNMP service as a Windows Server 2003 component. You need an account with Administrator privileges. Hands-on Networking Fundamentals 48

49 Activity 12-17: Configuring the SNMP Service in Windows Server Time Required: 10 minutes Objective: Learn how to configure the SNMP service. Description: In this activity, you learn how to configure the SNMP service and the SNMPTrap service in Windows Server Log on using an account with Administrator privileges. Plan to configure both services, particularly for use with Network Monitor and with third-party network management software. Hands-on Networking Fundamentals 49

50 Using Your Network for Backups Two options available Use backup device directly connected to target Back up files through network connection Example 1: home network with four computers Two computers contain shared schoolwork files Back up shared files onto hard drive of desktop Back up all four computers on separate media; e.g., CD Example 2: corporation with 25 servers, five tape silos Back up servers over network to tape silos Incremental backups performed Monday to Friday Comprehensive backup performed on Saturday Hands-on Networking Fundamentals 50

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52 Backup Services in Windows XP and Windows Server Use Backup or Restore Wizard in System Tools Different combinations of backups allowed Ability to restore backed up information provided Five backup options Normal: a file-by-file backup Incremental: backs up files marked with archive attribute Archive attribute removed from each file after the backup Differential: backs up all files marked archive attribute Does not remove the archive attribute Daily: backs up files changed on same day as backup Copy backup: backs up only specified files Hands-on Networking Fundamentals 52

53 Backup Service in UNIX/Linux dump utility: used for full or partial file-by-file backups Backups are often called "dumps" Dumps may be correlated to given point in time Dump restored via one of three commands tar utility: archives tapes and includes file information tar files can be used as archives Groups multiple files into single distribution file volcopy: binary backup available on some systems Creates a mirror image of a disk onto backup medium Can write to one or multiple tapes Hands-on Networking Fundamentals 53

54 How to Solve Network Problems Many types of network problems may be encountered Many effective troubleshooting techniques exist Strategies for problem solving to follow Hands-on Networking Fundamentals 54

55 Solving Client, Server, and Network Connectivity Problems Problems may be hardware or software related Examples: faulty cables, NICs, protocol setup A number of tasks that may be performed Check for proper installation of NIC driver Check NIC driver version (should be current) Verify protocol setup, particularly IP addressing Ensure that NIC properties are configured correctly Ensure computers have unique name and IP address Check cable connection into NIC or reconnect cable Ensure nodes configured for same security (wireless) Hands-on Networking Fundamentals 55

56 Solving NIC and WNIC Broadcast Problems Broadcast storm: broadcast flood saturating network Consequences: network slows down or times out One cause of a broadcast storm Continuous broadcast from malfunctioning NIC or WNIC Two options for tracing malfunctioning NIC or WNIC Use Network Monitor or System Monitor Use Protocol Analyzer Hands-on Networking Fundamentals 56

57 Solving Cable Problems Some symptoms Disconnecting workstations Slow network services High level of packet errors Some troubleshooting techniques on small networks Inspect visible cabling and connectors for damage Immediately replace damaged cable or parts Use Network Monitor, System Monitor, cable scanner Delegate troubleshooting to a network professional Tools used to troubleshoot large networks Network test equipment Enterprise-wide network-monitoring software Hands-on Networking Fundamentals 57

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59 Solving Wireless Problems Four techniques Observe distance requirements for wireless technology Configure security in same way on all devices Enables all wireless devices to communicate Use same roaming protocol in each cell (if cell roams) Use WNICs and access points using same technology Supports best throughput Example: all devices using g Hands-on Networking Fundamentals 59

60 Solving Network Printing Problems Best advice: check out simplest solutions first Make sure the printer has power Be certain the printer is online Press the printer reset button Make sure printer trays have paper Ensure that ink or toner cartridges are not depleted Four problem areas related to workstations or servers Printer driver is improperly installed/selected for print job Printer sharing is not enabled The printer share permissions are set incorrectly Print job software incorrectly installed at the workstation Hands-on Networking Fundamentals 60

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62 Designing a Solutions Strategy Built around three combined approaches Steps to prepare for solving problems Continue learning about how nodes interact with network Train network users to help Understand organizational context of network Steps to take when a problem surfaces Gather as much information as possible before analysis Check event logs and alerts Start with simple solutions Steps to take after you have solved a problem Keep a record describing problem and solution Problem log useful for future reference Hands-on Networking Fundamentals 62

63 Summary Network monitoring speeds up troubleshooting Multimeter combines functions of voltmeter and ohm meter Cable scanners test cable length using electrical signal Protocol analyzer captures protocol and OSI layer information Connection Status Dialog box: connection monitor built into Windows Hands-on Networking Fundamentals 63

64 Summary (continued) Command-line utilities for network monitoring: ping, traceroute, netstat, nslookup System Monitor can track network performance and network protocols Network Monitor uses captured frames and packets to analyze network performance SNMP provides network management services through agents and management systems Back up computers using internal device or device located on network Hands-on Networking Fundamentals 64

65 Summary (continued) Five backup options in Windows Backup utility UNIX/Linux backup utilities: dump, tar, volcopy Problem sources: network connectivity, broadcast storms, cabling Network printing problems often have simple solution Three-part problem solving strategy: identify problem, implement solution, log activities Hands-on Networking Fundamentals 65