internet working troubleshooting handbook (2nd edition)

C H A P T E R

PrefaceBecause of the rapid and ongoing developments in the field of networking, accurate troubleshooting information is an ever sought-after commodity. Because of this, the Cisco Press Internetworking Troubleshooting Handbook is a valuable resource for networking professionals throughout the industry. For the second edition of this book, we gathered together a team of troubleshooting experts who thoroughly revised the material in each of the technology areas to include the most current and relevant troubleshooting information and solutions available today. Their goal and ours was to provide networking professionals with a guide containing solutions to the problems encountered in the field in a format that is easy to apply. We hope that this publication meets that goal.

AudienceThe Internetworking Troubleshooting Handbook was written as a resource for anyone working in the field of networking who needs troubleshooting reference information. We anticipate that the information in this publication will assist users in solving specific technology issues and problems that they encounter in their existing environments.

AcknowledgmentsThe second edition of this unique guide is the outcome of a collaborative effort by a team of talented network troubleshooting experts headed by Cisco Systems Technical Assistance Center (TAC) manager, Janet Ramey. Contributors to this edition include the following current and former TAC Customer Support Engineers (in alphabetical order): Karim Benhabeje (CCIE #5010) Gerald Burgess (CCIE# 4540) Russ Emerson (CCIE #4206) Tim Gage (CCIE #3492) Brian Hutchins-Knowles(CCIE #4794) William M. Lee II Geraldine Nadela Nilesh Panicker Yongxia (Annie) Shi Francois Tallet (CCIE #3539)

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Tom Tobias (CCIE #6257) Robert Vigil (CCIE #1905) Russ White (CCIE #2635) Robert Wright (CCIE #1050) Gilbert Yip (CCIE #5070) Other contributors include the following: Kevin Burgess Mike Crane Steve Dussault Marion Jackson Johnson Liu William R. Wagner

Document ConventionsIn this publication, the following conventions are used:

Commands and keywords appear in boldface. New, important terms are italicized when accompanied by a definition or discussion of the term. Note is used to denote additional, helpful suggestions or references that otherwise do not appear in this book.

Our intent in updating this material and presenting it via Cisco Press is to deliver practical information to our customer community and the networking community at large. It is our hope that you find this material useful in your daily operations. The authors acknowledge that many current and former Cisco employees contributed to building the content of this publication. Key participants included Jim Young, Amir Khan, John Wright, Keith Redfield, Won Lee, Pasvorn Boonmark, Steve Cunningham, Nga Vu, Imran Qureshi, Atif Khan, Arun Sastry, John Bashinski, Dave Katz, Dino Farinacci, Larry Bowden, Praveen Akkiraju, Steve Russell, Srinivas Vegesna, Phil Remaker, Priscilla Oppenheimer, Bruce Pinsky, Joanna Gardner, Dennis Peng, Charlie Justus, Morris Ng, Sue Phelan, Mark Allen, Ivan Chan, Dennis Wind, Rasa Elena Lorenzana, Cerafin Castillo, John Chong, Jeff Schults, Jack Nichols, and Dianne Dunlap. The nature of this publications development required substantial management support to coordinate the subject matter and expert time spent in creating the material. The authors acknowledge Joe Pinto, Brad Wright, Doug Allred, and Charles Baugh as instrumental management sponsors who recognized the importance of this kind of material to customers and nurtured its creation during its early development stages. Principal authors of the first edition of this book were H. Kim Lew, Spank McCoy, Kathleen Wallace, Tim Stevenson, and Kevin Downes.

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Troubleshooting OverviewDependency on network resources has grown tremendously over the past ten years. In todays world, a companys success is highly dependent on its network availability. As a result, companies are increasingly less tolerant of network failures. Therefore, network troubleshooting has become a crucial element to many organizations. Not only has the dependency for network grown, but the industry also is moving toward increasingly complex environments, involving multiple media types, multiple protocols, and often interconnection to unknown networks. These unknown networks may be defined as a transit network belonging to a Internet service provider (ISP), or a telco that interconnects private networks. The convergence of voice and video into data networks has also added to the complexity and the importance of network reliability. More complex network environments mean that the potential for connectivity and performance problems in internetworks is high, and the source of problems is often elusive.

Symptoms, Problems, and SolutionsFailures in internetworks are characterized by certain symptoms. These symptoms might be general (such as clients being incapable of accessing specific servers) or more specific (routes not existing in a routing table). Each symptom can be traced to one or more problems or causes by using specific troubleshooting tools and techniques. After being identified, each problem can be remedied by implementing a solution consisting of a series of actions. This book describes how to define symptoms, identify problems, and implement solutions in generic environments. You should always apply the specific context in which you are troubleshooting to determine how to detect symptoms and diagnose problems for your specific environment.

General Problem-Solving ModelWhen youre troubleshooting a network environment, a systematic approach works best. An unsystematic approach to troubleshooting can result in wasting valuable time and resources, and can sometimes make symptoms even worse. Define the specific symptoms, identify all potential problems that could be causing the symptoms, and then systematically eliminate each potential problem (from most likely to least likely) until the symptoms disappear. Figure 1-1 illustrates the process flow for the general problem-solving model. This process flow is not a rigid outline for troubleshooting an internetwork; it is a foundation from which you can build a problem-solving process to suit your particular environment.


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Figure 1-1

General Problem-Solving Model

The following steps detail the problem-solving process outlined in Figure 1-1:Step 1

When analyzing a network problem, make a clear problem statement. You should define the problem in terms of a set of symptoms and potential causes. To properly analyze the problem, identify the general symptoms and then ascertain what kinds of problems (causes) could result in these symptoms. For example, hosts might not be responding to service requests from clients (a symptom). Possible causes might include a misconfigured host, bad interface cards, or missing router configuration commands.

Step 2

Gather the facts that you need to help isolate possible causes. Ask questions of affected users, network administrators, managers, and other key people. Collect information from sources such as network management systems, protocol analyzer traces, output from router diagnostic commands, or software release notes.

Step 3

Consider possible problems based on the facts that you gathered. Using the facts, you can eliminate some of the potential problems from your list. Depending on the data, for example, you might be able to eliminate hardware as a problem so that you can focus on software problems. At every opportunity, try to narrow the number of potential problems so that you can create an efficient plan of action.

Step 4

Create an action plan based on the remaining potential problems. Begin with the most likely problem, and devise a plan in which only one variable is manipulated. Changing only one variable at a time enables you to reproduce a given solution to a specific problem. If you alter more than one variable simultaneously, you might solve the problem, but identifying the specific change that eliminated the symptom becomes far more difficult and will not help you solve the same problem if it occurs in the future.


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Step 5 Step 6

Implement the action plan, performing each step carefully while testing to see whether the symptom disappears. Whenever you change a variable, be sure to gather results. Generally, you should use the same method of gathering facts that you used in Step 2 (that is, working with the key people affected, in conjunction with utilizing your diagnostic tools). Analyze the results to determine whether the problem has been resolved. If it has, then the process is complete. If the problem has not been resolved, you must create an action plan based on the next most likely problem in your list. Return to Step 4, change one variable at a time, and repeat the process until the problem is solved.

Step 7 Step 8

Note

If you exhaust all the common causes and actionseither those outlined in this book or ones that you have identified for your environmentyou should contact your Cisco technical support representative.

Preparing for Network FailureIt is always easier to recover from a network failure if you are prepared ahead of time. Possibly the most important requirement in any network environment is to have current and accurate information about that network available to the network support personnel at all times. Only with complete information can intelligent decisions be made about network change, and only with complete information can troubleshooting be done as quickly and as easily as possible. During the process of network troubleshooting, the network is expected to exhibit abnormal behavior. Therefore, it is always a good practice to set up a maintenance time window for troubleshooting to minimize any business impact. Always document any changes being made so that it is easier to back out if troubleshooting has failed to identify the problem within the maintenance window. To determine whether you are prepared for a network failure, answer the following questions:

Do you have an accurate physical and logical map of your internetwork? Does your organization or department have an up-to-date internetwork map that outlines the physical location of all the devices on the network and how they are connected, as well as a logical map of network addresses, network numbers, subnetworks, and so forth?

Do you have a list of all network protocols implemented in your network? For each of the protocols implemented, do you have a list of the network numbers, subnetworks, zones, areas, and so on that are associated with them?

Do you know which protocols are being routed? For each routed protocol, do you have correct, up-to-date router configuration? Do you know which protocols are being bridged? Are any filters configured in any bridges, and do you have a copy of these configurations? Do you know all the points of contact to external networks, including any connections to the Internet? For each external network connection, do you know what routing protocol is being used? Do you have an established baseline for your network?


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Has your organization documented normal network behavior and performance at different times of the day so that you can compare the current problems with a baseline? If you can answer yes to all questions, you will be able to recover from a failure more quickly and more easily than if you are not prepared. Lastly, for every problem solved, be sure to document the problems with solutions provided. This way, you will create a problem/answer database that others in your organization can refer to in case similar problems occur later. This will invariably reduce the time to troubleshoot your networks and, consequently, minimize your business impact.


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Troubleshooting ToolsThis chapter presents information about the wide variety of tools available to assist you in troubleshooting your internetwork. This includes information on using router diagnostic commands, Cisco network management tools, and third-party troubleshooting tools.

Using Router Diagnostic CommandsCisco routers provide numerous integrated commands to assist you in monitoring and troubleshooting your internetwork. The following sections describe the basic use of these commands:

The show commands help monitor installation behavior and normal network behavior, as well as isolate problem areas. The debug commands assist in the isolation of protocol and configuration problems. The ping commands help determine connectivity between devices on your network. The trace commands provide a method of determining the route by which packets reach their destination from one device to another.

Using show CommandsThe show commands are powerful monitoring and troubleshooting tools. You can use the show commands to perform a variety of functions:

Monitor router behavior during initial installation Monitor normal network operation Isolate problem interfaces, nodes, media, or applications Determine when a network is congested Determine the status of servers, clients, or other neighbors show versionDisplays the configuration of the system hardware, the software version, the names and sources of configuration files, and the boot images. show running-configDisplays the router configuration currently running. show startup-configDisplays the router configuration stored in nonvolatile RAM (NVRAM).

The following are some of the most commonly used show commands:


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show interfacesDisplays statistics for all interfaces configured on the router or access server. The resulting output varies, depending on the network for which an interface has been configured. show controllersDisplays statistics for interface card controllers. show flashDisplays the layout and contents of Flash memory. show buffersDisplays statistics for the buffer pools on the router. show memory summaryDisplays memory pool statistics and summary information about the activities of the system memory allocator, and gives a block-by-block listing of memory use. show process cpuDisplays information about the active processes on the router. show stacksDisplays information about the stack utilization of processes and interrupt routines, as well as the reason for the last system reboot. show cdp neighborsProvides a degree of reachability information of directly connected Cisco devices. This is an extremely useful tool to determine the operational status of the physical and data link layer. Cisco Discovery Protocol (CDP) is a proprietary data link layer protocol. show debuggingDisplays information about the type of debugging that is enabled for your router.

You can always use the ? at command line for a list of subcommands. Like the debug commands, some of the show commands listed previously are accessible only at the routers privileged exec mode (enable mode). This will be explained further in the Using debug commands section. Hundreds of other show commands are available. For details on using and interpreting the output of specific show commands, refer to the Cisco Internetwork Operating System (IOS) command references.

Using debug CommandsThe debug privileged exec commands can provide a wealth of information about the traffic being seen (or not seen) on an interface, error messages generated by nodes on the network, protocol-specific diagnostic packets, and other useful troubleshooting data. To access and list the privileged exec commands, enter this code: Router> enable Password: XXXXXX Router# ? Note the change in the router prompts here. The # prompt (instead of the normal > prompt) indicates that you are in the privileged exec mode (enable mode).

Caution

Exercise care when using debug commands. Many debug commands are processor-intensive and can cause serious network problems (such as degraded performance or loss of connectivity) if they are enabled on an already heavily loaded router. When you finish using a debug command, remember to disable it with its specific no debug command (or use the no debug all command to turn off all debugging). Use debug commands to isolate problems, not to monitor normal network operation. Because the high processor overhead of debug commands can disrupt router operation, you should use them only when you are looking for specific types of traffic or problems, and have narrowed your problems to a likely subset of causes.


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Output formats vary with each debug command. Some generate a single line of output per packet, and others generate multiple lines of output per packet. Some generate large amounts of output, and others generate only occasional output. Some generate lines of text, and others generate information in field format. To minimize the negative impact of using debug commands, follow this procedure:Step 1 Step 2

Use the no logging console global configuration command on your router. This command disables all logging to the console terminal. Telnet to a router port and enter the enable exec command. The enable exec command places the router in the privileged exec mode. After entering the enable password, you receive a prompt that consists of the router name with a # symbol. Use the terminal monitor command to copy debug command output and system error messages to your current terminal display. By redirecting output to your current terminal display, you can view debug command output remotely, without being connected through the console port. If you use debug commands at the console port, character-by-character processor interrupts are generated, maximizing the processor load already caused by using debug. If you intend to keep the output of the debug command, spool the output to a file. The procedure for setting up such a debug output file is described in the Debug Command Reference. This book refers to specific debug commands that are useful when troubleshooting specific problems. Complete details regarding the function and output of debug commands are provided in the Debug Command Reference. In many situations, using third-party diagnostic tools can be more useful and less intrusive than using debug commands. For more information, see the section Third-Party Troubleshooting Tools, later in this chapter.

Step 3

Using the ping CommandsTo check host reachability and network connectivity, use the ping command, which can be invoked from both user exec mode and privileged exec mode. After you log in to the router or access server, you are automatically in user exec command mode. The exec commands available at the user level are a subset of those available at the privileged level. In general, the user exec commands enable you to connect to remote devices, change terminal settings on a temporary basis, perform basic tests, and list system information. The ping command can be used to confirm basic network connectivity on AppleTalk, ISO Connectionless Network Service (CLNS), IP, Novell, Apollo, VINES, DECnet, or XNS networks. For IP, the ping command sends Internet Control Message Protocol (ICMP) Echo messages. ICMP is the Internet protocol that reports errors and provides information relevant to IP packet addressing. If a station receives an ICMP Echo message, it sends an ICMP Echo Reply message back to the source. The extended command mode of the ping command permits you to specify the supported IP header options. This allows the router to perform a more extensive range of test options. To enter ping extended command mode, enter yes at the extended commands prompt of the ping command. It is a good idea to use the ping command when the network is functioning properly to see how the command works under normal conditions and so that you have something to compare against when troubleshooting. For detailed information on using the ping and extended ping commands, refer to the Cisco IOS Configuration Fundamentals Command Reference.


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Using the trace CommandsThe trace user exec command discovers the routes that a routers packets follow when travelling to their destinations. The trace privileged exec command permits the supported IP header options to be specified, allowing the router to perform a more extensive range of test options. The trace command works by using the error message generated by routers when a datagram exceeds its time-to-live (TTL) value. First, probe datagrams are sent with a TTL value of 1. This causes the first router to discard the probe datagrams and send back time exceeded error messages. The trace command then sends several probes and displays the round-trip time for each. After every third probe, the TTL is increased by 1. Each outgoing packet can result in one of two error messages. A time exceeded error message indicates that an intermediate router has seen and discarded the probe. A port unreachable error message indicates that the destination node has received the probe and discarded it because it could not deliver the packet to an application. If the timer goes off before a response comes in, trace prints an asterisk (*). The trace command terminates when the destination responds, when the maximum TTL is exceeded, or when the user interrupts the trace with the escape sequence. As with ping, it is a good idea to use the trace command when the network is functioning properly to see how the command works under normal conditions and so that you have something to compare against when troubleshooting. For detailed information on using the trace and extended trace commands, refer to the Cisco IOS Configuration Fundamentals Command Reference.

Using Cisco Network Management ToolsCisco offers the CiscoWorks 2000 family of management products that provide design, monitoring, and troubleshooting tools to help you manage your internetwork. The following internetwork management tools are useful for troubleshooting internetwork problems:

CiscoView provides dynamic monitoring and troubleshooting functions, including a graphical display of Cisco devices, statistics, and comprehensive configuration information. Internetwork Performance Monitor (IPM) empowers network engineers to proactively troubleshoot network response times utilizing real-time and historical reports. The TrafficDirector RMON application, a remote monitoring tool, enables you to gather data, monitor activity on your network, and find potential problems. The VlanDirector switch management application is a management tool that provides an accurate picture of your VLANs.

CiscoViewCiscoView graphical management features provide dynamic status, statistics, and comprehensive configuration information for Cisco internetworking products (switches, routers, hubs, concentrators, and access servers). CiscoView aids network management by displaying a physical view of Cisco devices and color-coding device ports for at-a-glance port status, allowing users to quickly grasp essential information. Features include the following:


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Graphical displays of Cisco products from a central location, giving network managers a complete view of Cisco products without physically checking each device at remote sites A continuously updated physical view of routers, hubs, switches, or access servers in a network, regardless of physical location Updated real-time monitoring and tracking of key information and data relating to device performance, traffic, and usage, with metrics such as utilization percentage, frames transmitted and received, errors, and a variety of other device-specific indicators The capability to modify configurations such as trap, IP route, virtual LAN (VLAN), and bridge configurations

Internetwork Performance MonitorIPM is a network management application that enables you to monitor the performance of multiprotocol networks. IPM measures the response time and availability of IP networks on a hop-by-hop (router-to-router) basis. It also measures response time between routers and the mainframe in Systems Network Architecture (SNA) networks. Use IPM to perform the following tasks:

Troubleshoot problems by checking the network latency between devices Send Simple Network Management Protocol (SNMP) traps and SNA alerts when a user-configured threshold is exceeded, when a connection is lost and re-established, or when a timeout occurs Analyze potential problems before they occur by accumulating statistics, which are used to model and predict future network topologies Monitor response time between two network end points

The IPM product is composed of three parts: the IPM server, the IPM client application, and the response time reporter (RTR) feature of the Cisco IOS software.

The TrafficDirector RMON ApplicationThe TrafficDirector advanced packet filters let users monitor all seven layers of network traffic. Using Cisco IOS embedded RMON agents and SwitchProbe standalone probes, managers can view enterprise-wide network traffic from the link, network, transport, or application layers. The TrafficDirector multilayer traffic summary provides a quick, high-level assessment of network loading and protocol distributions. Network managers then zoom in on a specific segment, ring, switch port, or trunk link and apply real-time analysis and diagnostic tools to view hosts, conversations, and packet captures. TrafficDirector threshold monitoring enables users to implement a proactive management environment. First, thresholds for critical Management Information Base (MIB) variables are set within the RMON agent. When these thresholds are exceeded, traps are sent to the appropriate management station to notify the network administrator of an impending problem.

The VlanDirector Switch Management ApplicationThe VlanDirector switch management application simplifies VLAN port assignment and offers other management capabilities for VLANs. VlanDirector offers the following features for network administrators:


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Accurate representation of the physical network for VLAN design and configuration verification Capability to obtain VLAN configuration information on a specific device or link interface Discrepancy reports on conflicting configurations Capability to troubleshoot and identify individual device configurations that are in error with system-level VLANs Quick detection of changes in VLAN status of switch ports User authentication and write protection security

Third-Party Troubleshooting ToolsIn many situations, third-party diagnostic tools can be more useful than commands that are integrated into the router. For example, enabling a processor-intensive debug command can be disastrous in an environment experiencing excessively high traffic levels. However, attaching a network analyzer to the suspect network is less intrusive and is more likely to yield useful information without interrupting the operation of the router. The following are some typical third-party troubleshooting tools used for troubleshooting internetworks:

Volt-ohm meters, digital multimeters, and cable testers are useful in testing the physical connectivity of your cable plant. Time domain reflectors (TDRs) and optical time domain reflectors (OTDRs) are devices that assist in the location of cable breaks, impedance mismatches, and other physical cable plant problems. Breakout boxes, fox boxes, and BERTs/BLERTs are useful for troubleshooting problems in peripheral interfaces. Network monitors provide an accurate picture of network activity over a period of time by continuously tracking packets crossing a network. Network analyzers such as sniffers decode problems at all seven OSI layers and can be identified automatically in real time, providing a clear view of network activity and categorizing problems by criticality.

Volt-Ohm Meters, Digital Multimeters, and Cable TestersVolt-ohm meters and digital multimeters are at the lower end of the spectrum of cable-testing tools. These devices measure parameters such as AC and DC voltage, current, resistance, capacitance, and cable continuity. They are used to check physical connectivity. Cable testers (scanners) also enable you to check physical connectivity. Cable testers are available for shielded twisted-pair (STP), unshielded twisted-pair (UTP), 10BaseT, and coaxial and twinax cables. A given cable tester might be capable of performing any of the following functions:

Test and report on cable conditions, including near-end crosstalk (NEXT), attenuation, and noise Perform TDR, traffic monitoring, and wire map functions Display Media Access Control (MAC)layer information about LAN traffic, provide statistics such as network utilization and packet error rates, and perform limited protocol testing (for example, TCP/IP tests such as ping)

Similar testing equipment is available for fiber-optic cable. Because of the relatively high cost of this cable and its installation, fiber-optic cable should be tested both before installation (on-the-reel testing) and after installation. Continuity testing of the fiber requires either a visible light source or a


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reflectometer. Light sources capable of providing light at the three predominant wavelengths850 nanometers (nm), 1300 nm, and 1550 nmare used with power meters that can measure the same wavelengths and test attenuation and return loss in the fiber.

TDRs and OTDRsAt the top end of the cable testing spectrum are TDRs. These devices can quickly locate open and short circuits, crimps, kinks, sharp bends, impedance mismatches, and other defects in metallic cables. A TDR works by bouncing a signal off the end of the cable. Opens, shorts, and other problems reflect the signal back at different amplitudes, depending on the problem. A TDR measures how much time it takes for the signal to reflect and calculates the distance to a fault in the cable. TDRs can also be used to measure the length of a cable. Some TDRs can also calculate the propagation rate based on a configured cable length. Fiber-optic measurement is performed by an OTDR. OTDRs can accurately measure the length of the fiber, locate cable breaks, measure the fiber attenuation, and measure splice or connector losses. An OTDR can be used to take the signature of a particular installation, noting attenuation and splice losses. This baseline measurement can then be compared with future signatures when a problem in the system is suspected.

Breakout Boxes, Fox Boxes, and BERTs/BLERTsBreakout boxes, fox boxes, and bit/block error rate testers (BERTs/BLERTs) are digital interface testing tools used to measure the digital signals present at PCs, printers, modems, the channel service unit/digital service unit (CSU/DSU), and other peripheral interfaces. These devices can monitor data line conditions, analyze and trap data, and diagnose problems common to data communication systems. Traffic from data terminal equipment (DTE) through data communications equipment (DCE) can be examined to help isolate problems, identify bit patterns, and ensure that the proper cabling has been installed. These devices cannot test media signals such as Ethernet, Token Ring, or FDDI.

Network MonitorsNetwork monitors continuously track packets crossing a network, providing an accurate picture of network activity at any moment, or a historical record of network activity over a period of time. They do not decode the contents of frames. Monitors are useful for baselining, in which the activity on a network is sampled over a period of time to establish a normal performance profile, or baseline. Monitors collect information such as packet sizes, the number of packets, error packets, overall usage of a connection, the number of hosts and their MAC addresses, and details about communications between hosts and other devices. This data can be used to create profiles of LAN traffic as well as to assist in locating traffic overloads, planning for network expansion, detecting intruders, establishing baseline performance, and distributing traffic more efficiently.

Network AnalyzersA network analyzer (also called a protocol analyzer) decodes the various protocol layers in a recorded frame and presents them as readable abbreviations or summaries, detailing which layer is involved (physical, data link, and so forth) and what function each byte or byte content serves.


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Most network analyzers can perform many of the following functions:

Filter traffic that meets certain criteria so that, for example, all traffic to and from a particular device can be captured Time stamp-captured data Present protocol layers in an easily readable form Generate frames and transmit them onto the network Incorporate an expert system in which the analyzer uses a set of rules, combined with information about the network configuration and operation, to diagnose and solve, or offer potential solutions to, network problems


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Troubleshooting Hardware and Booting ProblemsThis chapter provides procedures for troubleshooting hardware and booting problems. Although it provides specific procedures for some Cisco products, always refer to your hardware installation and maintenance publication for more detailed information about your specific platform, including descriptions of specific LEDs, configuration information, and additional troubleshooting information. This chapter begins with the following sections on hardware problems:

Cisco 7500 Series StartupDescribes hardware and boot process troubleshooting for Cisco 7500 series routers Cisco 7000 Series StartupDescribes hardware and boot process troubleshooting for Cisco 7000 series routers Cisco 4000 Series StartupDescribes hardware and boot process troubleshooting for Cisco 4000 series routers Cisco 2500 Series StartupDescribes hardware and boot process troubleshooting for Cisco 2500 series routers Catalyst 5000 Series StartupDescribes hardware and boot process troubleshooting for Catalyst 5000 series LAN switches Catalyst 2900 Series StartupDescribes hardware and boot process troubleshooting for Catalyst 2900 series LAN switches Testing and Verifying Replacement PartsProvides suggested actions when swapping router hardware Catalyst 6000 Series StartupDescribes hardware and boot process troubleshooting for Catalyst 6000 series LAN switches Cisco 2600 Series StartupDescribes hardware and boot process troubleshooting for Cisco 2600 series routers Cisco 3600 Series StartupDescribes hardware and boot process troubleshooting for Cisco 3600 series routers Catalyst 4000 Series StartupDescribes hardware and boot process troubleshooting for Catalyst 4000 series LAN switches

The remaining sections describe symptoms, problems, and solutions for Flash boot, network boot using TFTP, ROM boot, and other bootup problems:

Booting: Router Fails to Boot from Flash Memory Booting: Vector Error Occurs When Booting from Flash Memory


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Booting: Router Partially Boots from Flash and Displays Boot Prompt Booting: Router Cannot Network boot from TFTP Server Booting: Router Cannot Network boot from Another Router Booting: Timeouts and Out-of-Order Packets Prevent Network booting Booting: Invalid Routes Prevent Network booting Booting: Client ARP Requests Timeout During Network boot Booting: Undefined Load Module Error When Network booting Booting: Router Hangs After ROM Monitor Initializes Booting: Router Is Stuck in ROM Monitor Mode Booting: Scrambled Output When Booting from ROM Booting: Local Timeouts Occur When Booting from ROM Booting: Unresponsive Terminal Connection to Unconfigured Access Server

Booting the RouterCisco routers can initialize the system (boot) in four ways:

Network bootRouters can boot from a server using the Trivial File Transfer Protocol (TFTP), the DEC Maintenance Operation Protocol (MOP), or the Remote Copy Protocol (RCP) across any of the supported media types (such as Ethernet, Token Ring, Fiber Distributed Data Interface [FDDI], High-Speed Serial Interface [HSSI], and serial lines). Flash memoryRouters can boot from Flash memory, a nonvolatile storage medium that can be electrically erased and reprogrammed. ROMRouters can boot a system from built-in read-only memory (ROM). PC Flash memory cardRouters can boot from a removable Flash memory card.

This section provides general information about router booting.

Network Booting TipsDuring network booting sessions, routers behave like hosts. They route via proxy Address Resolution Protocol (ARP), Serial Line Address Resolution Protocol (SLARP) information, Internet Control Message Protocol (ICMP) redirects, or a default gateway. When network booting, routers ignore dynamic routing information, static IP routes, and bridging information. As a result, intermediate routers are responsible for handling ARP and User Datagram Protocol (UDP) requests correctly. For serial and HSSI media, ARP is not used. Before network booting from a server, you should ping the server from the ROM software. If you cannot ping the server, follow the procedures described in the section Booting: Router Cannot Network boot from TFTP Server, later in this chapter. If you still cannot ping the server, there is probably a server configuration or hardware problem. Refer to your TFTP server documentation, or contact your technical support representative for assistance.


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Troubleshooting Hardware and Booting Problems Booting the Router

Fault-Tolerant Boot StrategiesAlthough network booting is useful, network or server failures can make network booting impossible. After you have installed and configured the routers Flash memory, configure the boot sequence for the router to reduce the impact of a server or network failure. The following order is recommended:1. 2. 3.

Boot an image from Flash memory. Boot an image using a network boot. Boot from a ROM image.

The following is an example of how to configure a router with a fault-tolerant boot sequence.goriot# configure terminal Enter configuration commands, one per line. End with CNTL/Z. goriot(config)# boot system flash gsxx goriot(config)# boot system gsxx 131.108.1.101 goriot(config)# boot system rom goriot(config)# ^Z goriot# %SYS-5-CONFIG_I: Configured from console by console goriot# copy running-config startup-config [ok] goriot#

Using this strategy, a router has three sources from which to boot: Flash memory, network boot, and ROM. Providing alternative sources can help to mitigate any failure of the TFTP server or the network.

Note

The configuration register must be set to allow ROM image booting after failed network booting attempts. For more information, refer to the hardware configuration manual for your platform.

Timeouts and Out-of-Order PacketsWhen network booting, a client might need to retransmit requests before receiving a response to an ARP request. These retransmissions can result in timeouts and out-of-order packets. Timeouts (shown as periods in a network booting display) and out-of-order packets (shown as uppercase Os) do not necessarily prevent a successful network boot. It is acceptable to have either or both timeouts or out-of-order packets occur during the network boot process. The following examples show console output from network booting sessions that were successful even though timeouts and out-of-order packets occurred (exclamation points represent successfully received packets): Booting gs3-bfx from 131.108.1.123: !.!!!!!!!!!!!!!!!!!!!!!!

Booting gs3-bfx from 131.108.1.123: !O.O!!!!!!!!!!!!!!!!!!!!!! If a network boot generates excessive out-of-order packets and timeouts, problems might result. These problems are discussed later in this chapter, in the section Booting: Timeouts and Out-of-Order Packets Prevent Network booting.


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Chapter 3 Troubleshooting Hardware


Information for Technical SupportIf you cannot resolve your booting problem using the procedures outlined in this chapter, collect the following information for your technical support representative:

ROM images. (Use the show version exec command.) Programmable ROM labels. (This information is printed on the physical chip, and an example is shown in Figure 3-1.)An Example of a Boot ROM LabelBoot ROM Version 11.1(2)

Figure 3-1

U30 v11 1(2) RS P2-ROMMON O17-2111-04 Cisco Systems

NVRAM configurations for client and adjacent routers. Debugging output from adjacent routers using the following privileged exec commands: debug ip packet debug arp debug ip udp debug tftp

For more information about these debug commands, refer to the Debug Command Reference.

Troubleshooting HardwareThis section discusses procedures for connectivity problems related to booting. It describes specific booting symptoms, the problems that are likely to cause each symptom, and the solutions to those problems.

Cisco 7500 Series StartupWhen you start up a Cisco 7500 series router, the following should occur:

The AC (or DC) OK LED should go on immediately and should remain on as long as the system is receiving power. The blower should be operating. The Route Switch Processor (RSP) and front-panel Normal LEDs should go on (to indicate normal system operation) and should remain on during system operation; the CPU Halt LED should remain off. The Enabled LED on each interface processor should go on (to indicate that the RSP has completed initialization of the interface processor).


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Troubleshooting Hardware and Booting Problems Troubleshooting Hardware

When the 7500 series system has initialized successfully, the system banner should be displayed on the console screen. If it is not displayed, make sure that the console terminal is properly connected to the RSP console port and that the terminal is set correctly. The system banner should look similar to the following:System Bootstrap, Version 4.6(5), SOFTWARE Copyright (c) 1986-1995 by cisco Systems RSP2 processor with 16384 Kbytes of memory ### [...] ### F3: 2012356+47852+194864 at 0x1000 Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013. cisco Systems, Inc. 170 Tasman Drive San Jose, CA 95134 GS Software (RSP-K), Version 10.3(571) [fc3], RELEASE SOFTWARE Copyright (c) 1986-1995 by cisco Systems, Inc. [...] Press RETURN to get started!

If a problem occurs, try to isolate the problem to a specific subsystem. The Cisco 7500 series routers have the following subsystems:

Power subsystemIncludes power supplies, external power cable, and backplane Cooling subsystemDepending on your system, includes the following: Cisco 7505Fan tray, fan tray spare with six individual fans, and fan control board Cisco 7507Chassis blower Cisco 7513Blower module, including blower, blower-speed control board, front-panel LEDs,

and the module itself

Processor subsystemDepending on your system, includes all interface processors and either the RSP1 or the RSP2


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Table 3-1 outlines the areas where Cisco 7500 series startup problems may occur and describes solutions to those problems.


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Table 3-1

Hardware: Cisco 7500 Series Startup Problems and Solutions

Possible Problem Area Power subsystem

Solution1.

Check to see whether the blower is operating and that LEDs on the processor modules are on. If the blower and LEDs are on but the Power Supply LED is off, there is probably a faulty Power Supply LED. Make sure that the power switch is set correctly to the on position. Make sure that the power source, power cable, and power supply are functioning correctly. Swap parts to see whether one of the components is faulty. Ensure that the blower module is seated properly. Make sure that the blower control board edge connector is inserted fully in the backplane socket.

2. 3.

4.


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Table 3-1

Hardware: Cisco 7500 Series Startup Problems and Solutions (continued)

Possible Problem Area Cooling subsystem

Solution1.

Check to see whether the blower is operating when you start up the system. If the blower is not operating, there might be a problem with the blower or the +24 V DC power: If the Output Fail LED is on, there might be a problem with the +24V DC supply to the blower or fan tray at either the power supply or the blower control board. If the blower is not operating and the Output Fail LED is off, ensure that the blower module is seated properly. Ensure that the blower control board edge connector is inserted fully in the backplane socket. If the system and blower start up but shut down after about 2 minutes, one or more fans might have failed or might be operating out of tolerance. You will probably see an error message similar to the following: %ENVM-2-FAN: Fan has failed, shutdown in 2 minutes

2.

If the blower or the blower control board fails, you must replace the blower module.3.

If you see the following message at startup, the system has detected an overtemperature condition or out-of-tolerance power inside the chassis: Queued messages: %ENVM-1-SHUTDOWN: Environmental Monitor initiated shutdown

If an environmental shutdown results from an out-of-tolerance power condition, the Output Fail LED goes on before the system shuts down. This shutdown message might also indicate a faulty component or temperature sensor. Before the system shuts down, use the show environment or show environment table commands to display the internal chassis environment.4.

Ensure that heated exhaust air from other equipment is not entering the inlet vents and that there is sufficient clearance around the chassis to allow cooling air to flow.continues


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Table 3-1


Possible Problem Area Processor subsystem

Solution1.

Check the RSP1 LEDs. If no LEDs come on, ensure that the power supplies and blower are functioning properly. Check the seating of the RSP. If the RSP is not seated properly, it will hang the system. If the RSP CPU Halt LED is on, the system has detected a processor hardware failure. Contact a technical support representative for instructions. Check to see whether the RSP Normal LED is on, indicating that the system software has initialized successfully and that the system is operational. Check the Enabled LED on each interface processor. This LED should go on when the RSP has initialized the interface processor. If the Enabled LED on an individual interface processor is off, the interface processor might have pulled away from the backplane. If the interface processors are not seated properly, they will hang the system.

2. 3.

4.

5.

6.

1. RSP = Route Switch Processor


The DC OK LED should go on and should remain on as long as the system is receiving source power. The fans should be operating. The Route Processor (RP) Normal LED should go on and stay on to indicate normal system operation; the Halt CPU LED should remain off. The Enabled LED on the Switch Processor (SP) or Silicon Switch Processor (SSP) and each interface processor should go on when the RP has completed initialization of the interface processor or SP (or SSP) for operation.


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When the system has initialized successfully, the system banner should be displayed on the console screen. If it is not displayed, make sure that the console terminal is properly connected to the RP console port and that the terminal is set correctly. The system banner should look similar to the following:System Bootstrap, Version 4.6(5), SOFTWARE Copyright (c) 1986-1995 by cisco Systems RP1 processor with 16384 Kbytes of memory ### [...] ### F3: 2012356+47852+194864 at 0x1000

Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013. cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134-1706 GS Software (GS7), Version 10.3(1) [fc3], RELEASE SOFTWARE Copyright (c) 1986-1995 by cisco Systems, Inc. RP1 (68040) processor with 16384K bytes of memory. [...] Press RETURN to get started!

If problems occur, try to isolate the problem to a specific subsystem. The Cisco 7000 series routers have the following subsystems:

Power subsystemIncludes power supplies, fans, external power cable, and internal power harness that connects to the backplane Cooling subsystemDepending on your system, includes the following: Cisco 7000Chassis blower Cisco 7010Fan tray assembly, including six individual fans, the fan control board, and the

tray itself

Processor subsystemIncludes the RP, SP (or SSP), and all interface processors


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Table 3-2 outlines the areas where Cisco 7000 series startup problems may occur and describes solutions to those problems.Table 3-2 Hardware: Cisco 7000 Series Startup Problems and Solutions


Solution1. 2.

Check to see whether the DC OK LED is on. If the LED is not on but the fans are operating and LEDs on the processor modules are on, the Power Supply LED might be faulty. If the LED is not on and there is no other activity, make sure that the power switch is fully in the on position. Make sure that the power source, power cable, and power supply are functioning correctly. Swap parts to see whether one of the components is faulty. Ensure that the fan tray is seated properly. Make sure that the fan control board edge connector is inserted fully in the backplane socket. Check to see whether the fans are operating. If the fans are not operating and the DC OK LED is off, there might be a problem with the +24V DC power. Ensure that the fan tray is seated properly. Make sure that the fan control board edge connector is inserted fully in the backplane socket. If the system and the fans start up but shut down after about 2 minutes, one or more fans has failed or is operating out of tolerance. You will see an error message similar to the following: %ENVM-2-FAN: Fan array has failed, shutdown in 2 minutes

3. 4.

5.

Cooling subsystem

1. 2. 3.

4.

If one or more fans or the fan control board fails, you must replace the fan tray.5.

If you see the following error message, the system has detected an overtemperature condition or out-of-tolerance power inside the chassis: Queued messages: %ENVM-1-SHUTDOWN: Environmental Monitor initiated shutdown

If an environmental shutdown results from an out-of-tolerance power condition, the DC OK LED will go off before the system shuts down.


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Table 3-2


Possible Problem Area Cooling subsystem (continued)

Solution This shutdown message could also indicate a faulty component or temperature sensor. Use the show environment or show environment table command to display the internal chassis environment.6.

Make sure that heated exhaust air from other equipment is not entering the inlet vents, and that there is sufficient clearance around the chassis to allow cooling air to flow. Check to see whether the RP1 LEDs come on when system power is turned on. If none of the RP LEDs come on, make sure that both the fan and the power supply are functioning properly. If the power supply and fans appear operational but none of the RP LEDs are on, an improperly connected RP, SP 2 (or SSP3), or interface processor might have hung the bus. If the SP (or SSP) Enabled LED is off but any of the RP LEDs are on, make sure that the SP (or SSP) is seated in its slot properly. Check to see whether the Boot Error LED is on. If the LED is on, the system software is incapable of starting up. If you have a spare RP with the system software ROMs installed, replace the installed RP with the spare to see whether the system will boot. Check to see whether the RP CPU Halt LED is on. If it is, the system has detected a processor hardware failure. Contact a technical support representative for more information. Check to see whether all interface processor Enabled LEDs are on. If the Enabled LED on an individual interface processor is off, make sure that the interface processor has not pulled away from the backplane.

Processor subsystem

1. 2. 3.

4.

5.

6.

7. 8.

1. RP = Route Processor 2. SP = Switch Processor 3. SSP = Silicon Switch Processor


The System OK LED should come on and stay on as long as power is supplied. The fans should be operating.


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When the system has initialized successfully, the system banner should be displayed on the console screen. The system banner should look similar to the following:System Bootstrap, Version 4.14(9), SOFTWARE Copyright (c) 1986-1994 by cisco Systems 4000 processor with 16384 Kbytes of main memory Loading xx-j-mz.112-0.15 at 0x4A790, size = 3496424 bytes [OK] F3: 8988+3487404+165008 at 0x12000 Self decompressing the image : ###[...]#### [OK] Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013. cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134-1706

Cisco Internetwork Operating System Software IOS (tm) 4000 Software (XX-J-M), Version 11.2(0.15), BETA TEST SOFTWARE Copyright (c) 1986-1996 by cisco Systems, Inc. Compiled Wed 03-Jul-96 01:21 by susingh Image text-base: 0x00012000, data-base: 0x006F6494

cisco 4000 (68030) processor (revision 0xA0) with 16384K/4096K bytes of memory. Processor board ID 5007155 G.703/E1 software, Version 1.0. Bridging software. SuperLAT software copyright 1990 by Meridian Technology Corp). X.25 software, Version 2.0, NET2, BFE and GOSIP compliant. TN3270 Emulation software (copyright 1994 by TGV Inc). Basic Rate ISDN software, Version 1.0. 2 Ethernet/IEEE 802.3 interfaces. 4 Serial network interfaces. 8 ISDN Basic Rate interfaces. 128K bytes of non-volatile configuration memory. 4096K bytes of processor board System flash (Read/Write) Press RETURN to get started!


Power subsystemThis subsystem includes the power supply and the wiring. Cooling subsystemThis subsystem includes the blower assembly, which should come on when power is applied. Network processor modules (NPMs)This subsystem includes all NPMs installed in the router chassis. System cablesThis subsystem includes all the external cables that connect the router to the network.


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Possible Problem Area Power and cooling subsystems

Solution1.

Check to see whether the blower is operating. If it is not, check the AC power input, AC power source, router circuit breaker, and power supply cable. If the system shuts down after being on a short time, check the power supply. If the power supply appears operational, the router might have shut down due to overheating. Check the console for error messages similar to the following: %SYS-1-OVERTEMP: System detected OVERTEMPERATURE condition. Please resolve cooling problem immediately!

2.

Make sure that the fans are working and that there is no air blockage to cooling vents.3.

If the system partially boots but LEDs do not light, contact your technical support representative. Make sure that NPMs are properly connected to the motherboard connector. Check the external cables. Check the processor or software for proper configuration. Check the external console connection and verify that the console baud rate is correct.

NPMs1 and cables

1. 2. 3. 4.

1. NPMs = network processor modules


The System OK LED should come on and stay on as long as power is supplied. The fans should be operating.


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When the system has initialized successfully, the system banner should be displayed on the console screen. The system banner should look similar to the following:System Bootstrap, Version (3.3), SOFTWARE Copyright (c) 1986-1993 by cisco Systems 2500 processor with 16384 Kbytes of main memory Unknown or ambiguous service arg - udp-small-servers Unknown or ambiguous service arg - tcp-small-servers Booting igs-in-l.110-9 from Flash address space F3: 3844616+90320+228904 at 0x3000060 Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013. cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134-1706

Cisco Internetwork Operating System Software IOS (tm) 3000 Software (IGS-IN-L), Version 11.0(9), RELEASE SOFTWARE (fc1) Copyright (c) 1986-1996 by cisco Systems, Inc. Compiled Tue 11-Jun-96 01:15 by loreilly Image text-base: 0x03020F8C, data-base: 0x00001000 cisco 2500 (68030) processor (revision A) with 16384K/2048K bytes of memory. Processor board ID 01062462, with hardware revision 00000000 Bridging software. X.25 software, Version 2.0, NET2, BFE and GOSIP compliant. Basic Rate ISDN software, Version 1.0. 1 Ethernet/IEEE 802.3 interface. 2 Serial network interfaces. 1 ISDN Basic Rate interface. 32K bytes of non-volatile configuration memory. 4096K bytes of processor board System flash (Read ONLY)

Press RETURN to get started!


Power subsystemThis subsystem includes the power supply and the wiring. Cooling subsystemThis subsystem includes the fan, which should go on when power is applied. Network interfacesThis subsystem includes all network interfaces, such as Ethernet, Token Ring, serial, or ISDN Basic Rate Interface (BRI). System cablesThis subsystem includes all the external cables that connect the router to the network.


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Possible Problem Area Power and cooling subsystems

Solution1.

If the Power LED is off, make sure that the power supply is plugged in to the wall receptacle and that the cable from the power supply to the router is connected. If the system shuts down after being on a short time, there might have been a thermal-induced shutdown caused by a faulty fan, or the power to the system might have been lost. Ensure that the system is receiving power and that the chassis intake and exhaust vents are clear. If the system does not boot up but LEDs are on, check the 12V power supply. If the system partially boots but LEDs are not on, check the 5V power supply. If a network interface is not recognized by the system, check the interface cable connection and the LED on the network interface. If a network interface is recognized but will not initialize, check the interface cable connection. If the system will not boot properly or constantly, or if it intermittently reboots, there might be a processor or software problem. Make sure that DRAM SIMM modules are seated properly. If the system boots but the console screen is frozen, check the external console connection and verify that the console baud rate is correct. If the system powers on and boots with a particular interface disconnected, check the network interface connection.

2.

3. 4.

Network interfaces and cables

1.

2. 3.

4.

5.

Catalyst 5000 Series StartupWhen you start up a Catalyst 5000 series LAN switch, the following should occur:

The PS1 and PS2 LEDs on the supervisor engine module faceplate should be green. The system fan assembly should be operating, and the Fan LED on the supervisor engine module should come on. The Status LED on the supervisor engine module and all interfaces should be orange until the boot is complete.


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When the system boot is complete, the supervisor engine module should initialize the switching modules. The status LED on each switching module goes on when initialization has been completed, and the console screen displays a script and system banner similar to the following:ATE0 ATS0=1 Catalyst 5000 Power Up Diagnostics Init NVRAM Log LED Test ROM CHKSUM DUAL PORT RAM r/w RAM r/w RAM address test Byte/Word Enable test RAM r/w 55aa RAM r/w aa55 EARL test BOOTROM Version 1.4, Dated Dec 5 1995 16:49:40 BOOT date: 00/00/00 BOOT time: 03:18:57 SIMM RAM address test SIMM Ram r/w 55aa SIMM Ram r/w aa55 Start to Uncompress Image ... IP address for Catalyst not configured BOOTP will commence after the ports are online Ports are coming online ... Cisco Systems Console

If problems occur, try to isolate the problem to a specific subsystem. The Catalyst 5000 series LAN switches have the following subsystems:

Power subsystemThis subsystem includes the power supplies and power supply fans. Cooling subsystemThis subsystem includes the chassis fan assembly, which should be operating when the system power is on. Processor and interface subsystemThis subsystem includes the supervisor engine module (which contains the system operating software), the network interfaces, and all associated cabling.


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Table 3-5 outlines the areas where Catalyst 5000 series startup problems may occur and describes solutions to those problems.Table 3-5 Hardware: Catalyst 5000 Series Startup Problems and Solutions


Solution1.

Check to see whether the PS1 LED is on. If it is not, ensure that the power supply is connected properly and is flush with the back of the chassis. Make sure that captive installation screws are tight. Check the AC source and the power cable. Connect the power cord to another power source, if one is available, and turn the power back on. If the LED fails to go on after you connect the power supply to a new power source, replace the power cord. If the LED fails to go on when the switch is connected to a different power source with a new power cord, the power supply is probably faulty. If a second power supply is available, install it in the second power supply bay, and contact a customer service representative for further instructions. Repeat these steps for the second power supply, if present. Check to see whether the Fan LED on the supervisor engine module is green. If it is not, check the power subsystem to see whether it is operational. If the Fan LED is red, the fan assembly might not be seated properly in the backplane.

2.

3.

4.

Cooling subsystem

1.

2.

To ensure that the fan assembly is seated properly, loosen the captive installation screws, remove the fan assembly, and reinstall it. Tighten all captive installation screws, and restart the system.3.

If the Fan LED is still red, the system has probably detected a fan assembly failure. Contact a technical support representative for assistance.continues Check the supervisor engine module Status and Link LEDs. These should both be green if all diagnostic and self-tests were successful and ports are operational. For more information about interpreting the supervisor engine module LEDs, refer to the user guide for your switch.

Processor and interface subsystem

1.

2.

Check the LEDs on individual interface modules. In most cases, these should be green (or should flicker green, in the case of Transmit and Receive LEDs) if the interface is functioning correctly. For detailed information on interpreting interface module LEDs, refer to the user guide for your switch. Check all cabling and connections. Replace any faulty cabling.

3.


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Catalyst 2900 Series StartupWhen you start up a Catalyst 2900 series LAN switch, the following should occur:

The PS LED on the supervisor engine module faceplate should come on and stay green while power is applied to the system. The system fan assembly and Fan LED should come on and stay on while power is applied to the system. The Status LED on the supervisor engine module and on each interface should be orange until the boot is complete.

When the system boot is complete, the supervisor engine module initializes the switching modules. The status LED on each switching module goes on when initialization has been completed, and the console screen displays a script and system banner similar to the following:BOOTROM Version 2.1, Dated May 22 1996 15:17:09 Boot date: 05/22/96 BOOT time: 15:17:09 Executing from RAM

Cisco Systems Console

Sending RARP request with address 00:40:0b:a0:05:b8 Sending bootp request with address 00:40:0b:a0:05:b8 Sending RARP request with address 00:40:0b:a0:05:b8 Sending bootp request with address 00:40:0b:a0:05:b8 No bootp or rarp response received Enter password:

If problems occur, try to isolate the problem to a specific subsystem. The Catalyst 2900 series LAN switches have the following subsystems:

Power subsystemThis subsystem includes the power supplies and power supply fans. Cooling subsystemThis subsystem includes the chassis fan assembly, which should be operating when the system power is on. Processor and interface subsystemThis subsystem includes the supervisor engine module (which contains the system operating software), the network interfaces, and all associated cabling.


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Table 3-6 outlines the areas where Catalyst 2900 series startup problems may occur and describes solutions to those problems.Table 3-6 Hardware: Catalyst 2900 Series Startup Problems and Solutions


Solution1.

Check the Power LED. If it is off, ensure that the power supply cord is not damaged and that it is properly attached to the power supply and to an AC receptacle. If the LED is red, the power supply has detected an anomaly or voltage outage and needs to be serviced. Contact your technical support representative for instructions. Check to see whether the Fan LED on the supervisor engine module is green. If it is not, check the power subsystem to see whether it is operational. If the Fan LED is red, contact a technical support representative for assistance. Check the supervisor engine module Status and Link LEDs. These should both be green if all diagnostic and self-tests were successful and ports are operational. For more information about interpreting the supervisor engine module LEDs, refer to the user guide for your switch. Check the LEDs on individual interface modules. In most cases, these should be green (or should flicker green, in the case of transmit and receive LEDs) if the interface is functioning correctly. For detailed information on interpreting interface module LEDs, refer to the user guide for your switch. Check all cabling and connections. Replace any faulty cabling.

2.

Cooling subsystem

1.

2.

Series processor and interface subsystem

1.

2.

3.

Testing and Verifying Replacement PartsIf you are replacing a part or card to remedy a suspected problem, make only one change at a time. To test a system, start with a simple hardware configuration and add one card at a time until a failed interface appears or is isolated. Use a simple software configuration, and test connectivity using a ping test. If you determine that a part or card replacement is required, contact your sales or technical support representative. Specific instructions concerning part or card installation are outlined in the configuration note provided with the replacement. For modular routers, make sure that you seat all cards correctly. Check the seating of cards if the system is not booting properly. Use the ejector levers to reseat all processor modules, and then reboot.

Caution

Before accessing the chassis interior and removing any cards, turn off power to the chassis. Use extreme caution around the chassis. Potentially harmful voltages are present.


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Troubleshooting Hardware and Booting Problems Troubleshooting Booting Problems

Caution

To prevent damage to components that are sensitive to electrostatic discharge (ESD), attach ESD protection before opening a chassis. Make certain that the power cord is connected but that power is off. ESD damage prevention guidelines are provided in the hardware installation and maintenance publication for your router. If a part replacement appears to solve a problem, reinstall the suspect part to verify the failure. Always double-check a repair.

Troubleshooting Booting ProblemsThis section discusses troubleshooting procedures for connectivity problems related to booting. It describes specific booting symptoms, the problems that are likely to cause each symptom, and the solutions to those problems.

Booting: Router Fails to Boot from Flash MemorySymptom: When a user is booting a router from Flash memory, the boot process appears to complete, but the router does not route traffic or communicate with neighbors. In addition, exec commands might or might not appear to function.


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Table 3-7 outlines the problems that might cause this symptom and describes solutions to those problems.


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Table 3-7

Booting: Router Fails to Boot from Flash Memory

Possible Problem Incorrect or corrupted image (exec does not function)

Solution1.

Check the configuration register using the show version exec command. Set the register to boot from Flash memory. For information about configuration register settings, refer to your hardware installation and maintenance documentation. Power-cycle the router. Within the first 60 seconds of booting, press the Break key to access the ROM monitor. At the ROM monitor prompt (>), enter o/r 0x1 to set the configuration register to boot from ROM. Enter i to reinitialize the router, which causes the router to enter setup mode. Obtain the correct system image. If necessary, contact your technical support representative to determine which image is correct. After the correct image is identified, use the copy tftp flash privileged exec command at the router to retrieve the image. Check the configuration register using the show version exec command. Set the register to boot from Flash memory. Use the show running-config privileged exec command to see whether the router configuration contains the boot system flash global configuration command.

2. 3. 4. 5. 6.

7. 8. 9.

Note: Issuing the copy running-config startup-config command at this point on a Cisco 2500, Cisco 3000, Cisco 4000, or Cisco 7000 series will overwrite the configuration. Make sure that you have a backup of your configuration file.10. Include the boot system flash command, if it is not in the

configuration. Be sure to use the copy running-config startup-config command after this change.11. Enter the reload privileged exec command to restart the

router. Syntax: The following is the syntax for the reload command: reload [text] | [in [hh:]mm [text]] | [at hh:mm [month day | day month] [text]] | [cancel]continues


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Table 3-7

Booting: Router Fails to Boot from Flash Memory (continued)

Possible Problem Incorrect or corrupted image (exec does not function) (continued)

Solution Examples: The following example illustrates how to use the reload command to immediately reload the software on the router: Router# reload The following example illustrates how to use the reload command to reload the software on the router in 10 minutes: Router# reload in 10 Router# Reload scheduled for 11:57:08 PDT Fri Apr 21 1996 (in 10 minutes) Proceed with reload? [confirm] Router#


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Table 3-7

Booting: Router Fails to Boot from Flash Memory (continued)

Possible Problem Incorrect or corrupted image (exec functions)

Solution1.

Obtain the correct system image. If necessary, contact your technical support representative to determine which image is appropriate. Use the copy tftp flash privileged exec command to retrieve the image. Check the configuration register using the show version exec command. Set the register to boot from Flash memory. For information about configuration register settings, refer to your hardware installation and maintenance documentation. Use the show running-config privileged exec command to determine whether the active configuration contains the boot system flash global configuration command. Use the show startup-config privileged exec command to determine whether the boot system flash command is included in the configuration stored in NVRAM1. Include the boot system flash command, if it is not in the configuration. Be sure to use the copy running-config startup-config privileged exec command to save your modification after this change. Enter the reload privileged exec command to restart the router.

2. 3.

4.

5.

6.

Syntax: The following is the syntax for the reload command: reload [text] | [in [hh:]mm [text]] | [at hh:mm [month day | day month] [text]] | [cancel] Examples: The following example illustrates how to use the reload command to immediately reload the software on the router:Router# reload

Incorrect or corrupted image (exec functions) (continued)

The following example illustrates how to use the reload command to reload the software on the router in 10 minutes: Router# reload in 10 Router# Reload scheduled for 11:57:08 PDT Fri Apr 21 1996 (in 10 minutes) Proceed with reload? [confirm] Router#

1. NVRAM = nonvolatile random-access memory


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Booting: Vector Error Occurs When Booting from Flash MemorySymptom: Vector errors occur when a user is booting a router from Flash memory.


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Table 3-8 outlines the problems that might cause this symptom and describes solutions to those problems.


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Table 3-8

Booting: Vector Error Occurs When Booting from Flash Memory

Possible Problem Compressed system image

Solution1. 2. 3. 4. 5. 6. 7.

Power-cycle the router. Within the first 60 seconds of booting, press the Break key to access the ROM monitor. At the ROM monitor prompt (>), enter o/r to set the configuration register to boot from ROM. Enter b to boot the router. The router enters setup mode. Press Ctrl-C to bypass the setup. Enter the configure memory privileged exec command. Obtain an uncompressed system image. From the router prompt, use the privileged exec command copy flash tftp to send the compressed image back to the TFTP1 server.

Decompress the image at the TFTP server. This cannot be done at the router.8.

Use the copy tftp flash privileged exec command at the router to retrieve the uncompressed image. The following is an example of the use of the copy tftp flash command: router# copy flash tftp filenamecontinues


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Table 3-8

Booting: Vector Error Occurs When Booting from Flash Memory (continued)

Possible Problem Compressed system image (continued)

Solution The router asks you for the IP address of the TFTP server and the name of the image file that you are copying to the server. A sample of the output for this command using IP address 131.108.10.6 and filename ic92130n follows: IP address of remote host [255.255.255.255]? 131.108.10.6 Name of file to copy []? ic92130n writing ic92130n !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! router#9.

Check the configuration register using the show version exec command. Set the router to boot from Flash memory. determine whether the router configuration includes the boot system flash global configuration command in the correct order with respect to the other boot system commands.

10. Use the show running-config privileged exec command to

Note: The boot system global configuration commands are saved in the order in which they were entered. The most recent entry goes to the bottom of the list. For the recommended ordering, refer to the section "Fault-Tolerant Boot Strategies," earlier in this chapter.11. Configure the boot system flash command, if it is missing.

Confirm that the order of boot system commands is correct. Use the copy running-config startup-config command to save this change. The required syntax is as follows: copy running-config {rcp | startup-config | tftp | file-id} (Cisco 7000, Cisco 7200, and Cisco 7500 series only) Syntax description: rcpSpecifies a copy operation to a network server using RCP. startup-configSpecifies the configuration used for initialization as the destination of the copy operation. The Cisco 4500 series cannot use this keyword. tftpSpecifies a TFTP server as the destination of the copy operation. file-idSpecifies device:filename as the destination of the copy operation. The device argument is optional, but when it is used, the colon (:) is required.12. Enter the reload privileged exec command to restart the

router. Router hardware problem Troubleshoot router hardware as discussed earlier in this chapter.


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1. TFTP = Trivial File Transfer Protocol

Booting: Router Partially Boots from Flash and Displays Boot PromptSymptom: When a user is booting a Cisco 2000, Cisco 2500, Cisco 3000, or Cisco 4000 series router from Flash memory, the boot process halts and the console displays the boot prompt [router(boot)>]. In addition, the router does not route, although exec commands might appear to be operational.


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Table 3-9 outlines the problems that might cause this symptom and describes solutions to those problems.Table 3-9 Booting: Router Partially Boots from Flash and Displays Boot Prompt

Possible Problem No system image in Flash memory

Solution1. 2.

Use the show flash exec command to determine whether an image exists in Flash memory. If no image exists, use the copy tftp flash privileged exec command to copy the system image from your TFTP1 server to the routers Flash memory. The following is an example of the use of the copy tftp flash command: router# copy flash tftp filename

The router asks you for the IP address of the TFTP server and the name of the image file that you are copying to the server. A sample of the output for this command using IP address 131.108.10.6 and filename ic92130n follows: IP address of remote host [255.255.255.255]? 131.108.10.6 Name of file to copy []? ic92130n writing ic92130n !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! router#3.

Enter the reload privileged exec command to reboot the router.

Syntax: The following is the syntax for the reload command: reload [text] | [in [hh:]mm [text]] | [at hh:mm [month day | day month] [text]] | [cancel] Examples: The following example illustrates how to use the reload command to immediately reload the software on the router: Router# reload The following example illustrates how to use the reload command to reload the software on the router in 10 minutes: Router# reload in 10 Router# Reload scheduled for 11:57:08 PDT Fri Apr 21 1996 (in 10 minutes) Proceed with reload? [confirm] Router#continues


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Table 3-9

Booting: Router Partially Boots from Flash and Displays Boot Prompt (continued)

Possible Problem Missing boot system flash global configuration command

Solution1.

Use the show running-config privileged exec command to determine whether the configuration includes a boot system flash global configuration command entry. Use the show startup-config privileged exec command to determine whether the boot system flash command is included in the configuration stored in NVRAM.2 Check the order of the boot system commands. For the recommended ordering, refer to the section "Fault-Tolerant Boot Strategies," earlier in this chapter. Add the boot system flash command or reorder the boot system commands, if necessary. Save the configuration change to NVRAM using the copy running-config startup-config privileged exec command. The required syntax is as follows:

2.

3. 4.

copy running-config {rcp | startup-config | tftp | file-id} (Cisco 7000, Cisco 7200, and Cisco 7500 series only)

Missing boot system flash global configuration command (continued)

Syntax description:

rcpSpecifies a copy operation to a network server using RCP. startup-configSpecifies the configuration used for initialization as the destination of the copy operation. The Cisco 4500 series cannot use this keyword. tftpSpecifies a TFTP server as the destination of the copy operation. file-idSpecifies a device:filename as the destination of the copy operation. The device argument is optional, but when it is used, the colon (:) is required.

Misconfigured configuration register

Use the show version exec command to check the configuration register setting. Make sure that it is set to boot from Flash memory. Refer to your hardware installation and maintenance publication for details regarding configuration

internet working troubleshooting handbook (2nd edition)

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