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IE 2000 Software Configuration Guide, Release 15.0(2)EA - Troubleshooting [Cisco Industrial Ethernet 2000 Series Switches] - Cisco
IE 2000 Software Configuration Guide, Release 15.0(2)EA
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IE 2000 Software Configuration Guide, Release 15.0(2)EA
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Troubleshooting
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Chapter: Troubleshooting
Chapter Contents
Troubleshooting
This chapter describes how to identify and resolve software problems related to the Cisco IOS software on the switch. Depending on the nature of the problem, you can use the command-line interface (CLI), Network Assistant or Device Manager to identify and solve problems.
For additional troubleshooting information, such as LED descriptions, see the Hardware Installation Guide.
Your software release may not support all the features documented in this chapter. For the latest feature information and caveats, see the release notes for your platform and software release.
The IEEE 802.3ab autonegotiation protocol manages the switch settings for speed (10 Mb/s, 100 Mb/s, and 1000 Mb/s, excluding SFP module ports) and duplex (half or full). There are situations when this protocol can incorrectly align these settings, reducing performance. A mismatch occurs under these circumstances:
A manually set speed or duplex parameter is different from the manually set speed or duplex parameter on the connected port.
A port is set to autonegotiate, and the connected port is set to full duplex with no autonegotiation.
To maximize switch performance and ensure a link, follow one of these guidelines when changing the settings for duplex and speed:
Let both ports autonegotiate both speed and duplex.
Manually set the speed and duplex parameters for the ports on both ends of the connection.
Note If a remote device does not autonegotiate, configure the duplex settings on the two ports to match. The speed parameter can adjust itself even if the connected port does not autonegotiate.
Cisco small form-factor pluggable (SFP) modules have a serial EEPROM that contains the module serial number, the vendor name and ID, a unique security code, and cyclic redundancy check (CRC). When an SFP module is inserted in the switch, the switch software reads the EEPROM to verify the serial number, vendor name and vendor ID, and recompute the security code and CRC. If the serial number, the vendor name or vendor ID, the security code, or CRC is invalid, the software generates a security error message and places the interface in an error-disabled state.
Note The security error message references the GBIC_SECURITY facility. The switch supports SFP modules and does not support GBIC modules. Although the error message text refers to GBIC interfaces and modules, the security messages actually refer to the SFP modules and module interfaces. For more information about error messages, see the system message guide for this release.
If you are using a non-Cisco SFP module, remove the SFP module from the switch, and replace it with a Cisco module. After inserting a Cisco SFP module, use the
errdisable recovery cause gbic-invalid global configuration command to verify the port status, and enter a time interval for recovering from the error-disabled state. After the elapsed interval, the switch brings the interface out of the error-disabled state and retries the operation. For more information about the
errdisable recovery command, see the command reference for this release.
If the module is identified as a Cisco SFP module, but the system is unable to read vendor-data information to verify its accuracy, an SFP module error message is generated. In this case, you should remove and reinsert the SFP module. If it continues to fail, the SFP module might be defective.
The switch supports IP ping, which you can use to test connectivity to remote hosts. Ping sends an echo request packet to an address and waits for a reply. Ping returns one of these responses:
Normal response—The normal response ( hostname is alive) occurs in 1 to 10 seconds, depending on network traffic.
Destination does not respond—If the host does not respond, a
no-answer message is returned.
Unknown host—If the host does not exist, an
unknown host message is returned.
Destination unreachable—If the default gateway cannot reach the specified network, a
destination-unreachable message is returned.
Network or host unreachable—If there is no entry in the route table for the host or network, a
network or host unreachable message is returned.
The Layer 2 traceroute feature allows the switch to identify the physical path that a packet takes from a source device to a destination device. Layer 2 traceroute supports only unicast source and destination MAC addresses. It finds the path by using the MAC address tables of the switches in the path. When the switch detects a device in the path that does not support Layer 2 traceroute, the switch continues to send Layer 2 trace queries and lets them time out.
The switch can only identify the path from the source device to the destination device. It cannot identify the path that a packet takes from source host to the source device or from the destination device to the destination host.
Cisco Discovery Protocol (CDP) must be enabled on all the devices in the network. For Layer 2 traceroute to function properly, do not disable CDP.
If any devices in the physical path are transparent to CDP, the switch cannot identify the path through these devices. For more information about enabling CDP, see
A switch is reachable from another switch when you can test connectivity by using the
ping privileged EXEC command. All switches in the physical path must be reachable from each other.
The maximum number of hops identified in the path is ten.
You can enter the
traceroute mac or the traceroute mac ip privileged EXEC command on a switch that is not in the physical path from the source device to the destination device. All switches in the path must be reachable from this switch.
traceroute mac command output shows the Layer 2 path only when the specified source and destination MAC addresses belong to the same VLAN. If you specify source and destination MAC addresses that belong to different VLANs, the Layer 2 path is not identified, and an error message appears.
If you specify a multicast source or destination MAC address, the path is not identified, and an error message appears.
If the source or destination MAC address belongs to multiple VLANs, you must specify the VLAN to which both the source and destination MAC addresses belong. If the VLAN is not specified, the path is not identified, and an error message appears.
traceroute mac ip
command output shows the Layer 2 path when the specified source and destination IP addresses belong to the same subnet. When you specify the IP addresses, the switch uses the Address Resolution Protocol (ARP) to associate the IP addresses with the corresponding MAC addresses and the VLAN IDs.
– If an ARP entry exists for the specified IP address, the switch uses the associated MAC address and identifies the physical path.
– If an ARP entry does not exist, the switch sends an ARP query and tries to resolve the IP address. If the IP address is not resolved, the path is not identified, and an error message appears.
When multiple devices are attached to one port through hubs (for example, multiple CDP neighbors are detected on a port), the Layer 2 traceroute feature is not supported. When more than one CDP neighbor is detected on a port, the Layer 2 path is not identified, and an error message appears.
You can use IP traceroute to identify the path that packets take through the network on a hop-by-hop basis. The command output displays all network layer (Layer 3) devices, such as routers, that the traffic passes through on the way to the destination.
Your switches can participate as the source or destination of the
traceroute privileged EXEC command and might or might not appear as a hop in the
traceroute command output. If the switch is the destination of the traceroute, it is displayed as the final destination in the traceroute output. Intermediate switches do not show up in the traceroute output if they are only bridging the packet from one port to another within the same VLAN. However, if the intermediate switch is a multilayer switch that is routing a particular packet, this switch shows up as a hop in the traceroute output.
traceroute privileged EXEC command uses the Time To Live (TTL) field in the IP header to cause routers and servers to generate specific return messages. Traceroute starts by sending a User Datagram Protocol (UDP) datagram to the destination host with the TTL field set to 1. If a router finds a TTL value of 1 or 0, it drops the datagram and sends an Internet Control Message Protocol (ICMP) time-to-live-exceeded message to the sender. Traceroute finds the address of the first hop by examining the source address field of the ICMP time-to-live-exceeded message.
To identify the next hop, traceroute sends a UDP packet with a TTL value of 2. The first router decrements the TTL field by 1 and sends the datagram to the next router. The second router sees a TTL value of 1, discards the datagram, and returns the time-to-live-exceeded message to the source. This process continues until the TTL is incremented to a value large enough for the datagram to reach the destination host (or until the maximum TTL is reached).
To learn when a datagram reaches its destination, traceroute sets the UDP destination port number in the datagram to a very large value that the destination host is unlikely to be using. When a host receives a datagram destined to itself containing a destination port number that is unused locally, it sends an ICMP
port-unreachable error to the source. Because all errors except port-unreachable errors come from intermediate hops, the receipt of a port-unreachable error means that this message was sent by the destination port.
You can use the Time Domain Reflector (TDR) feature to diagnose and resolve cabling problems. When running TDR, a local device sends a signal through a cable and compares the reflected signal to the initial signal.
TDR is supported only on 10/100 and 10/100/1000 copper Ethernet ports. It is not supported on SFP module ports.
TDR can detect these cabling problems:
Open, broken, or cut twisted-pair wires—The wires are not connected to the wires from the remote device.
Shorted twisted-pair wires—The wires are touching each other or the wires from the remote device. For example, a shorted twisted pair can occur if one wire of the twisted pair is soldered to the other wire.
If one of the twisted-pair wires is open, TDR can find the length at which the wire is open.
Use TDR to diagnose and resolve cabling problems in these situations:
Replacing a switch
Setting up a wiring closet
Troubleshooting a connection between two devices when a link cannot be established or when it is not operating properly
The crashinfo files save information that helps Cisco technical support representatives to debug problems that caused the Cisco IOS image to fail (crash). The switch writes the crash information to the console at the time of the failure. The switch creates two types of crashinfo files:
Basic crashinfo file—The switch automatically creates this file the next time you boot up the Cisco IOS image after the failure.
Extended crashinfo file—The switch automatically creates this file when the system is failing.
The information in the basic file includes the Cisco IOS image name and version that failed, a list of the processor registers, and other switch-specific information. You can provide this information to the Cisco technical support representative by using the
show tech-support
privileged EXEC command.
Basic crashinfo files are kept in this directory on the flash file system:
flash:/crashinfo/.
The filenames are crashinfo_ n where
n is a sequence number.
Each new crashinfo file that is created uses a sequence number that is larger than any previously existing sequence number, so the file with the largest sequence number describes the most recent failure. Version numbers are used instead of a timestamp because the switches do not include a real-time clock. You cannot change the name of the file that the system will use when it creates the file. However, after the file is created, you can use the
rename privileged EXEC command to rename it, but the contents of the renamed file will not be displayed by the
show tech-support
privileged EXEC command. You can delete crashinfo files by using the
delete privileged EXEC command.
You can display the most recent basic crashinfo file (that is, the file with the highest sequence number at the end of its filename) by entering the
show tech-support privileged EXEC command. You also can access the file by using any command that can copy or display files, such as the
more or the
copy privileged EXEC command.
The switch creates the extended crashinfo file when the system is failing. The information in the extended file includes additional information that can help determine the cause of the switch failure. You provide this information to the Cisco technical support representative by manually accessing the file and using the
more or the
copy privileged EXEC command.
Extended crashinfo files are kept in this directory on the flash file system:
flash:/crashinfo_ext/.
The filenames are crashinfo_ext_ n where
n is a sequence number.
You can configure the switch to not create the extended creashinfo file by using the no exception crashinfo global configuration command.
This section lists some possible symptoms that could be caused by the CPU being too busy and shows how to verify a CPU utilization problem.
lists the primary types of CPU utilization problems that you can identify. It gives possible causes and corrective action with links to the
document .
Excessive CPU utilization might result in these symptoms, but the symptoms could also result from other causes.
Spanning tree topology changes
EtherChannel links brought down due to loss of communication
Failure to respond to management requests (ICMP ping, SNMP timeouts, slow Telnet or SSH sessions)
UDLD flapping
IP SLAs failures because of SLAs responses beyond an acceptable threshold
DHCP or IEEE 802.1x failures if the switch does not forward or respond to requests
To determine if high CPU utilization is a problem, enter the
show processes cpu sorted privileged EXEC command. Note the underlined information in the first line of the output example.
Switch# show processes cpu sorted
CPU utilization for five seconds: 8%/0%; one minute: 7%; five minutes: 8%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
140 .63% 0.37% 0.30% 0 HRPC qos request
100 .47% 0.14% 0.11% 0 HRPC pm-counters
192 .31% 0.14% 0.11% 0 Spanning Tree
143 8 37 216 0.15% 0.01% 0.00% 0 Exec
&output truncated&
This example shows normal CPU utilization. The output shows that utilization for the last 5 seconds is
8%/0%, which has this meaning:
The total CPU utilization is 8 percent, including both time running Cisco IOS processes and time spent handling interrupts.
The time spent handling interrupts is zero percent.
Table 47-1 Troubleshooting CPU Utilization Problems
Interrupt percentage value is almost as high as total CPU utilization value.
The CPU is receiving too many packets from the network.
Determine the source of the network packet. Stop the flow, or change the switch configuration. See the section on
Total CPU utilization is greater than 50% with minimal time spent on interrupts.
One or more Cisco IOS process is consuming too much CPU time. This is usually triggered by an event that activated the process.
Identify the unusual event, and troubleshoot the root cause. See the section on
For complete information about CPU utilization and how to troubleshoot utilization problems, see the
If a powered device (such as Cisco IP Phone 7910) connected to a PoE switch port is powered by an AC power source and loses power from the source, the device might enter an error-disabled state. To recover from an error-disabled state, enter the
shutdown interface configuration command, and then enter the
no shutdown interface command.
You can also configure automatic recovery on the switch to recover from the error-disabled state. Use
errdisable
recovery cause loopback and the
errdisable recovery interval
seconds global configuration commands automatically take the interface out of the error-disabled state after the specified period of time.
Use these commands to monitor the PoE port status:
show controllers power inline privileged EXEC command
show power inline privileged EXEC command
debug ilpower privileged EXEC command
See the command reference for this release for more information about the commands.
If a Cisco powered device is connected to a port, and you configure the port by using the
power inline never interface configuration command, a false link up can occur placing the port into an error-disabled state. To
take the port out of the error-disabled state, enter the
shutdown and the
no shutdown interface configuration commands.
You should not connect a Cisco powered device to a port that has been configured with the
power inline never command.
Table 47-2 PoE Troubleshooting Scenarios
Synptom or Problem
Trouble is on only one switch port. PoE and non-PoE devices do not work on this port, but do on other ports.
Possible Cause and Solution
Verify that the powered device works on another PoE port.
show run, show interface status, or show power inline
detail user EXEC commands to verify that the port is not shut down or error disabled.
Note Most switches turn off port power when the port is shut down, even though the IEEE specifications make this optional.
Verify that the Ethernet cable from the powered device to the switch port is good: Connect a known good non-PoE Ethernet device to the Ethernet cable, and make sure that the powered device establishes a link and exchanges traffic with another host.
Verify that the total cable length from the switch front panel to the powered device is not more than 100 meters.
Disconnect the Ethernet cable from the switch port. Use a short Ethernet cable to connect a known good Ethernet device directly to this port on the switch front panel (not on a patch panel). Verify that it can establish an Ethernet link and exchange traffic with another host, or ping the port VLAN SVI. Next, connect a powered device to this port, and verify that it powers on.
If a powered device does not power on when connected with a patch cord to the switch port, compare the total number of connected powered devices to the switch power budget (available PoE). Use the
show inline power and
show inline power detail commands to verify the amount of available power.
Symptom or Problem
Trouble is on all switch ports. Nonpowered Ethernet devices cannot establish an Ethernet link on any port, and PoE devices do not power on.
Possible Cause and Solution
If there is a continuous, intermittent, or reoccurring alarm related to power, replace the power supply if possible as it is a field-replacable unit. Otherwise, replace the switch.
If the problem is on a consecutive group of ports but not all ports, the power supply is probably not defective, and the problem could be related to PoE regulators in the switch.
show log privileged EXEC command to review alarms or system messages that previously reported PoE conditions or status changes.
If there are no alarms, use the
show interface status command to verify that the ports are not shut down or error-disabled. If ports are error-disabled, use the
no shut interface configuration commands to reenable the ports.
Use the show
env power and
show power inline privileged EXEC commands to review the PoE status and power budget (available PoE).
Review the running configuration to verify that
power inline never is not configured on the ports.
Connect a nonpowered Ethernet device directly to a switch port. Use only a short patch cord. Do not use the existing distribution cables. Enter the
interface configuration commands, and verify that an Ethernet link is established. If this connection is good, use a short patch cord to connect a powered device to this port and verify that it powers on. If the device powers on, verify that all intermediate patch panels are correctly connected.
Disconnect all but one of the Ethernet cables from switch ports. Using a short patch cord, connect a powered device to only one PoE port. Verify the powered device does not require more power than can be delivered by the switch port.
show power inline privileged EXEC command to verify that the powered device can receive power when the port is not shut down. Alternatively, watch the powered device to verify that it powers on.
If a powered device can power on when only one powered device is connected to the switch, enter the
no shut interface configuration commands on the remaining ports, and then reconnect the Ethernet cables one at a time to the switch PoE ports. Use the
show interface status and
show power inline privileged EXEC commands to monitor inline power statistics and port status.
If there is still no PoE at any port, a fuse might be open in the PoE section of the power supply. This normally produces an alarm. Check the log again for alarms reported earlier by system messages.
Symptom or Problem
After working normally, a Cisco phone or wireless access point intermittently reloads or disconnects from PoE.
Possible Cause and Solution
Verify all electrical connections from the switch to the powered device. Any unreliable connection results in power interruptions and irregular powered device functioning such as an erratic powered device disconnects and reloads.
Verify that the cable length is not more than 100 meters from the switch port to the powered device.
Notice what changes in the electrical environment at the switch location or what happens at the powered device when the disconnect occurs.
Notice whether any error messages appear at the same time a disconnect occurs. Use the
show log privileged EXEC command to review error messages.
Verify that an IP phone is not losing access to the Call Manager immediately before the reload occurs. (It might be a network problem and not a PoE problem.)
Replace the powered device with a non-PoE device, and verify that the device works correctly. If a non-PoE device has link problems or a high error rate, the problem might be an unreliable cable connection between the switch port and the powered device.
Symptom or Problem
A non-Cisco powered device is connected to a Cisco PoE switch, but never powers on or powers on and then quickly powers off. Non-PoE devices work normally.
Possible Cause and Solution
show power inline command to verify that the switch power budget (available PoE) is not depleted before or after the powered device is connected. Verify that sufficient power is available for the powered device type before you connect it.
show interface status command to verify that the switch detects the connected powered device.
show log command to review system messages that reported an overcurrent condition on the port. Identify the symptom precisely: Does the powered device initially power on, but then disconnect? If so, the problem might be an initial surge-in (or inrush) current that exceeds a current-limit threshold for the port.
Switch software can be corrupted during an upgrade, by downloading the wrong file to the switch, and by deleting the image file. In all of these cases, the switch does not pass the power-on self-test (POST), and there is no connectivity.
This procedure uses the Xmodem Protocol to recover from a corrupt or wrong image file. There are many software packages that support the Xmodem Protocol, and this procedure is largely dependent on the emulation software that you are using.
This recovery procedure requires that you have physical access to the switch.
Step 1 From your PC, download the software image tar file ( image_filename.tar) .
The Cisco IOS image is stored as a
bin file in a directory in the tar file. For information about locating the software image files , see the release notes.
Step 2 Extract the bin file from the tar file.
If you are using Windows, use a zip program that can read a tar file. Use the zip program to navigate to and extract the bin file.
If you are using UNIX, follow these steps:
1. Display the contents of the tar file by using the
tar -tvf & image_filename.tar & UNIX command.
switch% tar -tvf image_filename.tar
2. Locate the bin file, and extract it by using the tar -xvf
& image_filename.tar & & image_filename.bin & UNIX command.
switch% tar -xvf image_filename.tar image_filename.binx
x image_name.bin, 3970586 bytes, 7756 tape blocks
3. Verify that the bin file was extracted by using the ls -l & image_filename.bin & UNIX command.
switch% ls -l image_filename.bin-rwxr-xr-x 1 bschuett eng 6365325 May 19 13:03
&insert path for lan base image&
-rw-r--r-- 1 boba 3970586 Apr 21 12:00 image_name.bin
Step 3 Connect your PC with terminal-emulation software supporting the Xmodem Protocol to the switch console port.
Step 4 Set the line speed on the emulation software to 9600 baud.
Step 5 Unplug the switch power cord.
Step 6 Press the
Express Setup button and at the same time, reconnect the power cord to the switch.
You can release the button a second or two after the LED above port 1 goes off. Several lines of information about the software appear along with instructions:
The system has been interrupted prior to initializing the flash file system. The following commands will initialize the flash file system, and finish loading the operating system software#
flash_init
load_helper
Step 7 Initialize the flash file system:
switch: flash_init
Step 8 If you had set the console port speed to anything other than 9600, it has been reset to that particular speed. Change the emulation software line speed to match that of the switch console port.
Step 9 Load any helper files:
switch: load_helper
Step 10 Start the file transfer by using the Xmodem Protocol.
switch: copy xmodem: flash:image_filename.bin
Step 11 After the Xmodem request appears, use the appropriate command on the terminal-emulation software to start the transfer and to copy the software image into flash memory.
Step 12 Boot the newly downloaded Cisco IOS image.
switch:boot flash:image_filename.bin
Step 13 Use the
archive download-sw privileged EXEC command to download the software image to the switch.
Step 14 Use the
reload privileged EXEC command to restart the switch and to verify that the new software image is operating properly.
Step 15 Delete the flash: image_filename.bin file from the switch.
If you lose or forget your password, you can delete the switch password and set a new one.
Before you begin, make sure that:
You have physical access to the switch.
At least one switch port is enabled and is not connected to a device.
To delete the switch password and set a new one, follow these steps:
Step 1 Press the
Express Setup button until the SETUP LED blinks green and the LED of an available switch downlink port blinks green.
If no switch downlink port is available for your PC or laptop connection, disconnect a device from one of the switch downlink ports. Press the
Express Setup button again until the SETUP LED and the port LED blink green.
Step 2 Connect your PC or laptop to the port with the blinking green LED.
The SETUP LED and the switch downlink port LED stop blinking and stay solid green.
Step 3 Press and hold the
Express Setup button. Notice that the SETUP LED starts blinking green again. Continue holding the button until the SETUP LED turns solid green (approximately 5 seconds). Release the
Express Setup button immediately.
This procedure deletes the password without affecting any other configuration settings. You can now access the switch without a password through the console port or by using Device Manager.
Step 4 Enter a new password through the device manager by using the Express Setup window or through the command line interface by using the
enable secret global configuration command.
Some configurations can prevent the command switch from maintaining contact with member switches. If you are unable to maintain management contact with a member, and the member switch is forwarding packets normally, check for these conflicts:
A member switch (Catalyst 3750, Catalyst 3560, Catalyst 3550, Catalyst 3500 XL, Catalyst 2970, Catalyst 2960, Catalyst 2950, Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900 switch) cannot connect to the command switch through a port that is defined as a network port.
Catalyst 3500 XL, Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900 member switches must connect to the command switch through a port that belongs to the same management VLAN.
A member switch (Catalyst 3750, Catalyst 3560, Catalyst 3550, Catalyst 2970, Catalyst 2960, Catalyst 2950, Catalyst 3500 XL, Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900 switch) connected to the command switch through a secured port can lose connectivity if the port is disabled because of a security violation.
If you attempt to ping a host in a different IP subnetwork, you must define a static route to the network or have IP routing configured to route between those subnets. For more information, see
IP routing is disabled by default on all switches. If you need to enable or configure IP routing, see
Beginning in privileged EXEC mode, use this command to ping another device on the network from the switch:
Pings a remote host through IP or by supplying the hostname or network address.
Note Other protocol keywords are available with the ping command, but they are not supported in this release.
This example shows how to ping an IP host:
Switch# ping 172.20.52.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 172.20.52.3, timeout is 2 seconds:
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
describes the possible ping character output.
Table 47-3 Ping Output Display Characters
Each exclamation point means receipt of a reply.
Each period means the network server timed out while waiting for a reply.
A destination unreachable error PDU was received.
A congestion experienced packet was received.
User interrupted test.
Unknown packet type.
Packet lifetime exceeded.
To end a ping session, enter the escape sequence (Ctrl-^ X by default). Simultaneously press and release the Ctrl,
Shift, and
6 keys and then press the
Beginning in privileged EXEC mode, follow this step to trace that the path packets take through the network:
traceroute ip
Traces the path that packets take through the network.
Note Other protocol keywords are available with the traceroute privileged EXEC command, but they are not supported in this release.
This example shows how to perform a
traceroute to an IP host:
Switch# traceroute ip 171.9.15.10
Type escape sequence to abort.
Tracing the route to 171.69.115.10
1 172.2.52.1 0 msec 0 msec 4 msec
2 172.2.1.203 12 msec 8 msec 0 msec
3 171.9.16.6 4 msec 0 msec 0 msec
4 171.9.4.5 0 msec 4 msec 0 msec
5 171.9.121.34 0 msec 4 msec 4 msec
6 171.9.15.9 120 msec 132 msec 128 msec
7 171.9.15.10 132 msec 128 msec 128 msec
The display shows the hop count, the IP address of the router, and the round-trip time in milliseconds for each of the three probes that are sent.
Table 47-4 Traceroute Output Display Characters
The probe timed out.
Unknown packet type.
Administratively unreachable. Usually, this output means that an access list is blocking traffic.
Host unreachable.
Network unreachable.
Protocol unreachable.
Source quench.
Port unreachable.
To end a trace in progress, enter the escape sequence (Ctrl-^ X by default). Simultaneously press and release the Ctrl,
Shift, and
6 keys and then press the
To run TDR, enter the test cable-diagnostics tdr interface
interface-id privileged EXEC command:
To display the results, enter the
show cable-diagnostics tdr interface
interface-id privileged EXEC command. For a description of the fields in the display, see the command reference for this release.
Because debugging output is assigned high priority in the CPU process, it can render the system unusable. For this reason, use
debug commands only to troubleshoot specific problems or during troubleshooting sessions with Cisco technical support staff. It is best to use
debug commands during periods of lower network traffic and fewer users. Debugging during these periods decreases the likelihood that increased
debug command processing overhead will affect system use.
debug commands are entered in privileged EXEC mode, and most
debug commands take no arguments. For example, beginning in privileged EXEC mode, enter this command to enable the debugging for Switched Port Analyzer (SPAN):
Switch# debug span-session
The switch continues to generate output until you enter the
no form of the command.
If you enable a
debug command and no output appears, consider these possibilities:
The switch might not be properly configured to generate the type of traffic you want to monitor. Use the
show running-config command to check its configuration.
Even if the switch is properly configured, it might not generate the type of traffic you want to monitor during the particular period that debugging is enabled. Depending on the feature you are debugging, you can use commands such as the TCP/IP
ping command to generate network traffic.
To disable debugging of SPAN, enter this command in privileged EXEC mode:
Switch# no debug span-session
Alternately, in privileged EXEC mode, you can enter the
undebug form of the command:
Switch# undebug span-session
To display the state of each debugging option, enter this command in privileged EXEC mode:
Switch# show debugging
Beginning in privileged EXEC mode, enter this command to enable all-system diagnostics:
Switch# debug all
Because debugging output takes priority over other network traffic, and because the
debug all privileged EXEC command generates more output than any other
debug command, it can severely diminish switch performance or even render it unusable. In virtually all cases, it is best to use more specific
debug commands.
no debug all privileged EXEC command disables all diagnostic output. Using the
no debug all
command is a convenient way to ensure that you have not accidentally left any
debug commands enabled.
By default, the network server sends the output from
debug commands and system error messages to the console. If you use this default, you can use a virtual terminal connection to monitor debug output instead of connecting to the console port.
Possible destinations include the console, virtual terminals, internal buffer, and UNIX hosts running a syslog server. The syslog format is compatible with 4.3 Berkeley Standard Distribution (BSD) UNIX and its derivatives.
Note Be aware that the debugging destination you use affects system overhead. Logging messages to the console produces very high overhead, whereas logging messages to a virtual terminal produces less overhead. Logging messages to a syslog server produces even less, and logging to an internal buffer produces the least overhead of any method.
For more information about system message logging, see
You can display the physical path that a packet takes from a source device to a destination device by using one of these privileged EXEC commands:
tracetroute mac
[ interface
interface-id ] { source-mac-address } [ interface
interface-id ] { destination-mac-address } [ vlan
vlan-id ] [ detail ]
tracetroute mac ip
{ source-ip-address | source-hostname }{ destination-ip-address | destination-hostname } [ detail ]
For more information, see the command reference for this release.
You can check the physical or operational status of an SFP module by using the
show interfaces transceiver privileged EXEC command. This command shows the operational status, such as the temperature and the current for an SFP module on a specific interface and the alarm status. You can also use the command to check the speed and the duplex settings on an SFP module. For more information, see the
show interfaces transceiver command in the command reference
for this release.
The output from the
show platform forward privileged EXEC command provides some useful information about the forwarding results if a packet entering an interface is sent through the system. Depending upon the parameters entered about the packet, the output provides lookup table results and port maps used to calculate forwarding destinations, bitmaps, and egress information.
Most of the information in the output from the command is useful mainly for technical support personnel, who have access to detailed information about the switch application-specific integrated circuits (ASICs). However, packet forwarding information can also be helpful in troubleshooting.
This is an example of the output from the
show platform forward command on port 1 in VLAN 5 when the packet entering that port is addressed to unknown MAC addresses. The packet should be flooded to all other ports in VLAN 5.
Switch# show platform forward gigabitethernet1/1 vlan 5 1.1.1 2.2.2 ip 13.1.1.1 13.2.2.2 udp 10 20
Global Port Number:24, Asic Number:5
Src Real Vlan Id:5, Mapped Vlan Id:5
Lookup Key-Used Index-Hit A-Data
InptACL 40_0DD_A0000 01FFA
L2Local 80_00 00C71 0000002B
Station Descriptor:, DestIndex:0239, RewriteIndex:F005
==========================================
Egress:Asic 2, switch 1
Output Packets:
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_0DD_A0000 01FFE
Port Vlan SrcMac DstMac Cos Dscpv
Gi1/1 01.02.0002
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_0DD_A0000 01FFE
Port Vlan SrcMac DstMac Cos Dscpv
Gi1/1 01.02.0002
------------------------------------------
&output truncated&
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_0DD_A0000 01FFE
Packet dropped due to failed DEJA_VU Check on Gi1/0/2
Packet dropped due to failed DEJA_VU Check on Gi1/2
This is an example of the output when the packet coming in on port 1 in VLAN 5 is sent to an address already learned on the VLAN on another port. It should be forwarded from the port on which the address was learned.
Switch# show platform forward gigabitethernet1/1 vlan 5 1.1.1 .0145 ip 13.1.1.1 13.2.2.2 udp 10 20
Global Port Number:24, Asic Number:5
Src Real Vlan Id:5, Mapped Vlan Id:5
Lookup Key-Used Index-Hit A-Data
InptACL 40_0DD_A0000 01FFA
L2Local 80_A00 97
Station Descriptor:F0050003, DestIndex:F005, RewriteIndex:0003
==========================================
Egress:Asic 3, switch 1
Output Packets:
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_0DD_A0000 01FFE
Port Vlan SrcMac DstMac Cos Dscpv
interface-id 01.A8.0145
This is an example of the output when the packet coming in on port 1 in VLAN 5 has a destination MAC address set to the router MAC address in VLAN 5 and the destination IP address unknown. Because there is no default route set, the packet should be dropped.
Switch# show platform forward gigabitethernet1/1 vlan 5 1.1.1 03.e319.ee44 ip 13.1.1.1 13.2.2.2 udp 10 20
Global Port Number:24, Asic Number:5
Src Real Vlan Id:5, Mapped Vlan Id:5
Lookup Key-Used Index-Hit A-Data
InptACL 40_0DD_A0000 01FFA
L3Local 00_202 010F0
L3Scndr 12_0DD_A 000C001D_
Lookup Used:Secondary
Station Descriptor:, DestIndex:0226, RewriteIndex:0000
This is an example of the output when the packet coming in on port 1 in VLAN 5 has a destination MAC address set to the router MAC address in VLAN 5 and the destination IP address set to an IP address that is in the IP routing table. It should be forwarded as specified in the routing table.
Switch# show platform forward gigabitethernet1/1 vlan 5 1.1.1 03.e319.ee44 ip 110.1.5.5 16.1.10.5
Global Port Number:24, Asic Number:5
Src Real Vlan Id:5, Mapped Vlan Id:5
Lookup Key-Used Index-Hit A-Data
InptACL 40_A_A0000 01FFA
L3Local 00_A05 010F0
L3Scndr 12_A_A 00000
Lookup Used:Secondary
Station Descriptor:F0070007, DestIndex:F007, RewriteIndex:0007
==========================================
Egress:Asic 3, switch 1
Output Packets:
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_A_A0000 01FFE
Port Vlan SrcMac DstMac Cos Dscpv
Gi1/2 0007 XXXX.XXXX.A8.0147
The following sections provide references related to switch administration:
Cisco IE 2000 commands
Cisco IE 2000 Switch Command Reference, 15.0(1)EY
Cisco IOS basic commands
Cisco IOS Configuration Fundamentals Command Reference
Additional troubleshooting information
Hardware Installation Guide
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IE 2000 Software Configuration Guide, Release 15.0(2)EA
Book Contents
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IE 2000 Software Configuration Guide, Release 15.0(2)EA
Chapter Title
Troubleshooting
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Chapter: Troubleshooting
Chapter Contents
Troubleshooting
This chapter describes how to identify and resolve software problems related to the Cisco IOS software on the switch. Depending on the nature of the problem, you can use the command-line interface (CLI), Network Assistant or Device Manager to identify and solve problems.
For additional troubleshooting information, such as LED descriptions, see the Hardware Installation Guide.
Your software release may not support all the features documented in this chapter. For the latest feature information and caveats, see the release notes for your platform and software release.
The IEEE 802.3ab autonegotiation protocol manages the switch settings for speed (10 Mb/s, 100 Mb/s, and 1000 Mb/s, excluding SFP module ports) and duplex (half or full). There are situations when this protocol can incorrectly align these settings, reducing performance. A mismatch occurs under these circumstances:
A manually set speed or duplex parameter is different from the manually set speed or duplex parameter on the connected port.
A port is set to autonegotiate, and the connected port is set to full duplex with no autonegotiation.
To maximize switch performance and ensure a link, follow one of these guidelines when changing the settings for duplex and speed:
Let both ports autonegotiate both speed and duplex.
Manually set the speed and duplex parameters for the ports on both ends of the connection.
Note If a remote device does not autonegotiate, configure the duplex settings on the two ports to match. The speed parameter can adjust itself even if the connected port does not autonegotiate.
Cisco small form-factor pluggable (SFP) modules have a serial EEPROM that contains the module serial number, the vendor name and ID, a unique security code, and cyclic redundancy check (CRC). When an SFP module is inserted in the switch, the switch software reads the EEPROM to verify the serial number, vendor name and vendor ID, and recompute the security code and CRC. If the serial number, the vendor name or vendor ID, the security code, or CRC is invalid, the software generates a security error message and places the interface in an error-disabled state.
Note The security error message references the GBIC_SECURITY facility. The switch supports SFP modules and does not support GBIC modules. Although the error message text refers to GBIC interfaces and modules, the security messages actually refer to the SFP modules and module interfaces. For more information about error messages, see the system message guide for this release.
If you are using a non-Cisco SFP module, remove the SFP module from the switch, and replace it with a Cisco module. After inserting a Cisco SFP module, use the
errdisable recovery cause gbic-invalid global configuration command to verify the port status, and enter a time interval for recovering from the error-disabled state. After the elapsed interval, the switch brings the interface out of the error-disabled state and retries the operation. For more information about the
errdisable recovery command, see the command reference for this release.
If the module is identified as a Cisco SFP module, but the system is unable to read vendor-data information to verify its accuracy, an SFP module error message is generated. In this case, you should remove and reinsert the SFP module. If it continues to fail, the SFP module might be defective.
The switch supports IP ping, which you can use to test connectivity to remote hosts. Ping sends an echo request packet to an address and waits for a reply. Ping returns one of these responses:
Normal response—The normal response ( hostname is alive) occurs in 1 to 10 seconds, depending on network traffic.
Destination does not respond—If the host does not respond, a
no-answer message is returned.
Unknown host—If the host does not exist, an
unknown host message is returned.
Destination unreachable—If the default gateway cannot reach the specified network, a
destination-unreachable message is returned.
Network or host unreachable—If there is no entry in the route table for the host or network, a
network or host unreachable message is returned.
The Layer 2 traceroute feature allows the switch to identify the physical path that a packet takes from a source device to a destination device. Layer 2 traceroute supports only unicast source and destination MAC addresses. It finds the path by using the MAC address tables of the switches in the path. When the switch detects a device in the path that does not support Layer 2 traceroute, the switch continues to send Layer 2 trace queries and lets them time out.
The switch can only identify the path from the source device to the destination device. It cannot identify the path that a packet takes from source host to the source device or from the destination device to the destination host.
Cisco Discovery Protocol (CDP) must be enabled on all the devices in the network. For Layer 2 traceroute to function properly, do not disable CDP.
If any devices in the physical path are transparent to CDP, the switch cannot identify the path through these devices. For more information about enabling CDP, see
A switch is reachable from another switch when you can test connectivity by using the
ping privileged EXEC command. All switches in the physical path must be reachable from each other.
The maximum number of hops identified in the path is ten.
You can enter the
traceroute mac or the traceroute mac ip privileged EXEC command on a switch that is not in the physical path from the source device to the destination device. All switches in the path must be reachable from this switch.
traceroute mac command output shows the Layer 2 path only when the specified source and destination MAC addresses belong to the same VLAN. If you specify source and destination MAC addresses that belong to different VLANs, the Layer 2 path is not identified, and an error message appears.
If you specify a multicast source or destination MAC address, the path is not identified, and an error message appears.
If the source or destination MAC address belongs to multiple VLANs, you must specify the VLAN to which both the source and destination MAC addresses belong. If the VLAN is not specified, the path is not identified, and an error message appears.
traceroute mac ip
command output shows the Layer 2 path when the specified source and destination IP addresses belong to the same subnet. When you specify the IP addresses, the switch uses the Address Resolution Protocol (ARP) to associate the IP addresses with the corresponding MAC addresses and the VLAN IDs.
– If an ARP entry exists for the specified IP address, the switch uses the associated MAC address and identifies the physical path.
– If an ARP entry does not exist, the switch sends an ARP query and tries to resolve the IP address. If the IP address is not resolved, the path is not identified, and an error message appears.
When multiple devices are attached to one port through hubs (for example, multiple CDP neighbors are detected on a port), the Layer 2 traceroute feature is not supported. When more than one CDP neighbor is detected on a port, the Layer 2 path is not identified, and an error message appears.
You can use IP traceroute to identify the path that packets take through the network on a hop-by-hop basis. The command output displays all network layer (Layer 3) devices, such as routers, that the traffic passes through on the way to the destination.
Your switches can participate as the source or destination of the
traceroute privileged EXEC command and might or might not appear as a hop in the
traceroute command output. If the switch is the destination of the traceroute, it is displayed as the final destination in the traceroute output. Intermediate switches do not show up in the traceroute output if they are only bridging the packet from one port to another within the same VLAN. However, if the intermediate switch is a multilayer switch that is routing a particular packet, this switch shows up as a hop in the traceroute output.
traceroute privileged EXEC command uses the Time To Live (TTL) field in the IP header to cause routers and servers to generate specific return messages. Traceroute starts by sending a User Datagram Protocol (UDP) datagram to the destination host with the TTL field set to 1. If a router finds a TTL value of 1 or 0, it drops the datagram and sends an Internet Control Message Protocol (ICMP) time-to-live-exceeded message to the sender. Traceroute finds the address of the first hop by examining the source address field of the ICMP time-to-live-exceeded message.
To identify the next hop, traceroute sends a UDP packet with a TTL value of 2. The first router decrements the TTL field by 1 and sends the datagram to the next router. The second router sees a TTL value of 1, discards the datagram, and returns the time-to-live-exceeded message to the source. This process continues until the TTL is incremented to a value large enough for the datagram to reach the destination host (or until the maximum TTL is reached).
To learn when a datagram reaches its destination, traceroute sets the UDP destination port number in the datagram to a very large value that the destination host is unlikely to be using. When a host receives a datagram destined to itself containing a destination port number that is unused locally, it sends an ICMP
port-unreachable error to the source. Because all errors except port-unreachable errors come from intermediate hops, the receipt of a port-unreachable error means that this message was sent by the destination port.
You can use the Time Domain Reflector (TDR) feature to diagnose and resolve cabling problems. When running TDR, a local device sends a signal through a cable and compares the reflected signal to the initial signal.
TDR is supported only on 10/100 and 10/100/1000 copper Ethernet ports. It is not supported on SFP module ports.
TDR can detect these cabling problems:
Open, broken, or cut twisted-pair wires—The wires are not connected to the wires from the remote device.
Shorted twisted-pair wires—The wires are touching each other or the wires from the remote device. For example, a shorted twisted pair can occur if one wire of the twisted pair is soldered to the other wire.
If one of the twisted-pair wires is open, TDR can find the length at which the wire is open.
Use TDR to diagnose and resolve cabling problems in these situations:
Replacing a switch
Setting up a wiring closet
Troubleshooting a connection between two devices when a link cannot be established or when it is not operating properly
The crashinfo files save information that helps Cisco technical support representatives to debug problems that caused the Cisco IOS image to fail (crash). The switch writes the crash information to the console at the time of the failure. The switch creates two types of crashinfo files:
Basic crashinfo file—The switch automatically creates this file the next time you boot up the Cisco IOS image after the failure.
Extended crashinfo file—The switch automatically creates this file when the system is failing.
The information in the basic file includes the Cisco IOS image name and version that failed, a list of the processor registers, and other switch-specific information. You can provide this information to the Cisco technical support representative by using the
show tech-support
privileged EXEC command.
Basic crashinfo files are kept in this directory on the flash file system:
flash:/crashinfo/.
The filenames are crashinfo_ n where
n is a sequence number.
Each new crashinfo file that is created uses a sequence number that is larger than any previously existing sequence number, so the file with the largest sequence number describes the most recent failure. Version numbers are used instead of a timestamp because the switches do not include a real-time clock. You cannot change the name of the file that the system will use when it creates the file. However, after the file is created, you can use the
rename privileged EXEC command to rename it, but the contents of the renamed file will not be displayed by the
show tech-support
privileged EXEC command. You can delete crashinfo files by using the
delete privileged EXEC command.
You can display the most recent basic crashinfo file (that is, the file with the highest sequence number at the end of its filename) by entering the
show tech-support privileged EXEC command. You also can access the file by using any command that can copy or display files, such as the
more or the
copy privileged EXEC command.
The switch creates the extended crashinfo file when the system is failing. The information in the extended file includes additional information that can help determine the cause of the switch failure. You provide this information to the Cisco technical support representative by manually accessing the file and using the
more or the
copy privileged EXEC command.
Extended crashinfo files are kept in this directory on the flash file system:
flash:/crashinfo_ext/.
The filenames are crashinfo_ext_ n where
n is a sequence number.
You can configure the switch to not create the extended creashinfo file by using the no exception crashinfo global configuration command.
This section lists some possible symptoms that could be caused by the CPU being too busy and shows how to verify a CPU utilization problem.
lists the primary types of CPU utilization problems that you can identify. It gives possible causes and corrective action with links to the
document .
Excessive CPU utilization might result in these symptoms, but the symptoms could also result from other causes.
Spanning tree topology changes
EtherChannel links brought down due to loss of communication
Failure to respond to management requests (ICMP ping, SNMP timeouts, slow Telnet or SSH sessions)
UDLD flapping
IP SLAs failures because of SLAs responses beyond an acceptable threshold
DHCP or IEEE 802.1x failures if the switch does not forward or respond to requests
To determine if high CPU utilization is a problem, enter the
show processes cpu sorted privileged EXEC command. Note the underlined information in the first line of the output example.
Switch# show processes cpu sorted
CPU utilization for five seconds: 8%/0%; one minute: 7%; five minutes: 8%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
140 .63% 0.37% 0.30% 0 HRPC qos request
100 .47% 0.14% 0.11% 0 HRPC pm-counters
192 .31% 0.14% 0.11% 0 Spanning Tree
143 8 37 216 0.15% 0.01% 0.00% 0 Exec
&output truncated&
This example shows normal CPU utilization. The output shows that utilization for the last 5 seconds is
8%/0%, which has this meaning:
The total CPU utilization is 8 percent, including both time running Cisco IOS processes and time spent handling interrupts.
The time spent handling interrupts is zero percent.
Table 47-1 Troubleshooting CPU Utilization Problems
Interrupt percentage value is almost as high as total CPU utilization value.
The CPU is receiving too many packets from the network.
Determine the source of the network packet. Stop the flow, or change the switch configuration. See the section on
Total CPU utilization is greater than 50% with minimal time spent on interrupts.
One or more Cisco IOS process is consuming too much CPU time. This is usually triggered by an event that activated the process.
Identify the unusual event, and troubleshoot the root cause. See the section on
For complete information about CPU utilization and how to troubleshoot utilization problems, see the
If a powered device (such as Cisco IP Phone 7910) connected to a PoE switch port is powered by an AC power source and loses power from the source, the device might enter an error-disabled state. To recover from an error-disabled state, enter the
shutdown interface configuration command, and then enter the
no shutdown interface command.
You can also configure automatic recovery on the switch to recover from the error-disabled state. Use
errdisable
recovery cause loopback and the
errdisable recovery interval
seconds global configuration commands automatically take the interface out of the error-disabled state after the specified period of time.
Use these commands to monitor the PoE port status:
show controllers power inline privileged EXEC command
show power inline privileged EXEC command
debug ilpower privileged EXEC command
See the command reference for this release for more information about the commands.
If a Cisco powered device is connected to a port, and you configure the port by using the
power inline never interface configuration command, a false link up can occur placing the port into an error-disabled state. To
take the port out of the error-disabled state, enter the
shutdown and the
no shutdown interface configuration commands.
You should not connect a Cisco powered device to a port that has been configured with the
power inline never command.
Table 47-2 PoE Troubleshooting Scenarios
Synptom or Problem
Trouble is on only one switch port. PoE and non-PoE devices do not work on this port, but do on other ports.
Possible Cause and Solution
Verify that the powered device works on another PoE port.
show run, show interface status, or show power inline
detail user EXEC commands to verify that the port is not shut down or error disabled.
Note Most switches turn off port power when the port is shut down, even though the IEEE specifications make this optional.
Verify that the Ethernet cable from the powered device to the switch port is good: Connect a known good non-PoE Ethernet device to the Ethernet cable, and make sure that the powered device establishes a link and exchanges traffic with another host.
Verify that the total cable length from the switch front panel to the powered device is not more than 100 meters.
Disconnect the Ethernet cable from the switch port. Use a short Ethernet cable to connect a known good Ethernet device directly to this port on the switch front panel (not on a patch panel). Verify that it can establish an Ethernet link and exchange traffic with another host, or ping the port VLAN SVI. Next, connect a powered device to this port, and verify that it powers on.
If a powered device does not power on when connected with a patch cord to the switch port, compare the total number of connected powered devices to the switch power budget (available PoE). Use the
show inline power and
show inline power detail commands to verify the amount of available power.
Symptom or Problem
Trouble is on all switch ports. Nonpowered Ethernet devices cannot establish an Ethernet link on any port, and PoE devices do not power on.
Possible Cause and Solution
If there is a continuous, intermittent, or reoccurring alarm related to power, replace the power supply if possible as it is a field-replacable unit. Otherwise, replace the switch.
If the problem is on a consecutive group of ports but not all ports, the power supply is probably not defective, and the problem could be related to PoE regulators in the switch.
show log privileged EXEC command to review alarms or system messages that previously reported PoE conditions or status changes.
If there are no alarms, use the
show interface status command to verify that the ports are not shut down or error-disabled. If ports are error-disabled, use the
no shut interface configuration commands to reenable the ports.
Use the show
env power and
show power inline privileged EXEC commands to review the PoE status and power budget (available PoE).
Review the running configuration to verify that
power inline never is not configured on the ports.
Connect a nonpowered Ethernet device directly to a switch port. Use only a short patch cord. Do not use the existing distribution cables. Enter the
interface configuration commands, and verify that an Ethernet link is established. If this connection is good, use a short patch cord to connect a powered device to this port and verify that it powers on. If the device powers on, verify that all intermediate patch panels are correctly connected.
Disconnect all but one of the Ethernet cables from switch ports. Using a short patch cord, connect a powered device to only one PoE port. Verify the powered device does not require more power than can be delivered by the switch port.
show power inline privileged EXEC command to verify that the powered device can receive power when the port is not shut down. Alternatively, watch the powered device to verify that it powers on.
If a powered device can power on when only one powered device is connected to the switch, enter the
no shut interface configuration commands on the remaining ports, and then reconnect the Ethernet cables one at a time to the switch PoE ports. Use the
show interface status and
show power inline privileged EXEC commands to monitor inline power statistics and port status.
If there is still no PoE at any port, a fuse might be open in the PoE section of the power supply. This normally produces an alarm. Check the log again for alarms reported earlier by system messages.
Symptom or Problem
After working normally, a Cisco phone or wireless access point intermittently reloads or disconnects from PoE.
Possible Cause and Solution
Verify all electrical connections from the switch to the powered device. Any unreliable connection results in power interruptions and irregular powered device functioning such as an erratic powered device disconnects and reloads.
Verify that the cable length is not more than 100 meters from the switch port to the powered device.
Notice what changes in the electrical environment at the switch location or what happens at the powered device when the disconnect occurs.
Notice whether any error messages appear at the same time a disconnect occurs. Use the
show log privileged EXEC command to review error messages.
Verify that an IP phone is not losing access to the Call Manager immediately before the reload occurs. (It might be a network problem and not a PoE problem.)
Replace the powered device with a non-PoE device, and verify that the device works correctly. If a non-PoE device has link problems or a high error rate, the problem might be an unreliable cable connection between the switch port and the powered device.
Symptom or Problem
A non-Cisco powered device is connected to a Cisco PoE switch, but never powers on or powers on and then quickly powers off. Non-PoE devices work normally.
Possible Cause and Solution
show power inline command to verify that the switch power budget (available PoE) is not depleted before or after the powered device is connected. Verify that sufficient power is available for the powered device type before you connect it.
show interface status command to verify that the switch detects the connected powered device.
show log command to review system messages that reported an overcurrent condition on the port. Identify the symptom precisely: Does the powered device initially power on, but then disconnect? If so, the problem might be an initial surge-in (or inrush) current that exceeds a current-limit threshold for the port.
Switch software can be corrupted during an upgrade, by downloading the wrong file to the switch, and by deleting the image file. In all of these cases, the switch does not pass the power-on self-test (POST), and there is no connectivity.
This procedure uses the Xmodem Protocol to recover from a corrupt or wrong image file. There are many software packages that support the Xmodem Protocol, and this procedure is largely dependent on the emulation software that you are using.
This recovery procedure requires that you have physical access to the switch.
Step 1 From your PC, download the software image tar file ( image_filename.tar) .
The Cisco IOS image is stored as a
bin file in a directory in the tar file. For information about locating the software image files , see the release notes.
Step 2 Extract the bin file from the tar file.
If you are using Windows, use a zip program that can read a tar file. Use the zip program to navigate to and extract the bin file.
If you are using UNIX, follow these steps:
1. Display the contents of the tar file by using the
tar -tvf & image_filename.tar & UNIX command.
switch% tar -tvf image_filename.tar
2. Locate the bin file, and extract it by using the tar -xvf
& image_filename.tar & & image_filename.bin & UNIX command.
switch% tar -xvf image_filename.tar image_filename.binx
x image_name.bin, 3970586 bytes, 7756 tape blocks
3. Verify that the bin file was extracted by using the ls -l & image_filename.bin & UNIX command.
switch% ls -l image_filename.bin-rwxr-xr-x 1 bschuett eng 6365325 May 19 13:03
&insert path for lan base image&
-rw-r--r-- 1 boba 3970586 Apr 21 12:00 image_name.bin
Step 3 Connect your PC with terminal-emulation software supporting the Xmodem Protocol to the switch console port.
Step 4 Set the line speed on the emulation software to 9600 baud.
Step 5 Unplug the switch power cord.
Step 6 Press the
Express Setup button and at the same time, reconnect the power cord to the switch.
You can release the button a second or two after the LED above port 1 goes off. Several lines of information about the software appear along with instructions:
The system has been interrupted prior to initializing the flash file system. The following commands will initialize the flash file system, and finish loading the operating system software#
flash_init
load_helper
Step 7 Initialize the flash file system:
switch: flash_init
Step 8 If you had set the console port speed to anything other than 9600, it has been reset to that particular speed. Change the emulation software line speed to match that of the switch console port.
Step 9 Load any helper files:
switch: load_helper
Step 10 Start the file transfer by using the Xmodem Protocol.
switch: copy xmodem: flash:image_filename.bin
Step 11 After the Xmodem request appears, use the appropriate command on the terminal-emulation software to start the transfer and to copy the software image into flash memory.
Step 12 Boot the newly downloaded Cisco IOS image.
switch:boot flash:image_filename.bin
Step 13 Use the
archive download-sw privileged EXEC command to download the software image to the switch.
Step 14 Use the
reload privileged EXEC command to restart the switch and to verify that the new software image is operating properly.
Step 15 Delete the flash: image_filename.bin file from the switch.
If you lose or forget your password, you can delete the switch password and set a new one.
Before you begin, make sure that:
You have physical access to the switch.
At least one switch port is enabled and is not connected to a device.
To delete the switch password and set a new one, follow these steps:
Step 1 Press the
Express Setup button until the SETUP LED blinks green and the LED of an available switch downlink port blinks green.
If no switch downlink port is available for your PC or laptop connection, disconnect a device from one of the switch downlink ports. Press the
Express Setup button again until the SETUP LED and the port LED blink green.
Step 2 Connect your PC or laptop to the port with the blinking green LED.
The SETUP LED and the switch downlink port LED stop blinking and stay solid green.
Step 3 Press and hold the
Express Setup button. Notice that the SETUP LED starts blinking green again. Continue holding the button until the SETUP LED turns solid green (approximately 5 seconds). Release the
Express Setup button immediately.
This procedure deletes the password without affecting any other configuration settings. You can now access the switch without a password through the console port or by using Device Manager.
Step 4 Enter a new password through the device manager by using the Express Setup window or through the command line interface by using the
enable secret global configuration command.
Some configurations can prevent the command switch from maintaining contact with member switches. If you are unable to maintain management contact with a member, and the member switch is forwarding packets normally, check for these conflicts:
A member switch (Catalyst 3750, Catalyst 3560, Catalyst 3550, Catalyst 3500 XL, Catalyst 2970, Catalyst 2960, Catalyst 2950, Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900 switch) cannot connect to the command switch through a port that is defined as a network port.
Catalyst 3500 XL, Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900 member switches must connect to the command switch through a port that belongs to the same management VLAN.
A member switch (Catalyst 3750, Catalyst 3560, Catalyst 3550, Catalyst 2970, Catalyst 2960, Catalyst 2950, Catalyst 3500 XL, Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900 switch) connected to the command switch through a secured port can lose connectivity if the port is disabled because of a security violation.
If you attempt to ping a host in a different IP subnetwork, you must define a static route to the network or have IP routing configured to route between those subnets. For more information, see
IP routing is disabled by default on all switches. If you need to enable or configure IP routing, see
Beginning in privileged EXEC mode, use this command to ping another device on the network from the switch:
Pings a remote host through IP or by supplying the hostname or network address.
Note Other protocol keywords are available with the ping command, but they are not supported in this release.
This example shows how to ping an IP host:
Switch# ping 172.20.52.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 172.20.52.3, timeout is 2 seconds:
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
describes the possible ping character output.
Table 47-3 Ping Output Display Characters
Each exclamation point means receipt of a reply.
Each period means the network server timed out while waiting for a reply.
A destination unreachable error PDU was received.
A congestion experienced packet was received.
User interrupted test.
Unknown packet type.
Packet lifetime exceeded.
To end a ping session, enter the escape sequence (Ctrl-^ X by default). Simultaneously press and release the Ctrl,
Shift, and
6 keys and then press the
Beginning in privileged EXEC mode, follow this step to trace that the path packets take through the network:
traceroute ip
Traces the path that packets take through the network.
Note Other protocol keywords are available with the traceroute privileged EXEC command, but they are not supported in this release.
This example shows how to perform a
traceroute to an IP host:
Switch# traceroute ip 171.9.15.10
Type escape sequence to abort.
Tracing the route to 171.69.115.10
1 172.2.52.1 0 msec 0 msec 4 msec
2 172.2.1.203 12 msec 8 msec 0 msec
3 171.9.16.6 4 msec 0 msec 0 msec
4 171.9.4.5 0 msec 4 msec 0 msec
5 171.9.121.34 0 msec 4 msec 4 msec
6 171.9.15.9 120 msec 132 msec 128 msec
7 171.9.15.10 132 msec 128 msec 128 msec
The display shows the hop count, the IP address of the router, and the round-trip time in milliseconds for each of the three probes that are sent.
Table 47-4 Traceroute Output Display Characters
The probe timed out.
Unknown packet type.
Administratively unreachable. Usually, this output means that an access list is blocking traffic.
Host unreachable.
Network unreachable.
Protocol unreachable.
Source quench.
Port unreachable.
To end a trace in progress, enter the escape sequence (Ctrl-^ X by default). Simultaneously press and release the Ctrl,
Shift, and
6 keys and then press the
To run TDR, enter the test cable-diagnostics tdr interface
interface-id privileged EXEC command:
To display the results, enter the
show cable-diagnostics tdr interface
interface-id privileged EXEC command. For a description of the fields in the display, see the command reference for this release.
Because debugging output is assigned high priority in the CPU process, it can render the system unusable. For this reason, use
debug commands only to troubleshoot specific problems or during troubleshooting sessions with Cisco technical support staff. It is best to use
debug commands during periods of lower network traffic and fewer users. Debugging during these periods decreases the likelihood that increased
debug command processing overhead will affect system use.
debug commands are entered in privileged EXEC mode, and most
debug commands take no arguments. For example, beginning in privileged EXEC mode, enter this command to enable the debugging for Switched Port Analyzer (SPAN):
Switch# debug span-session
The switch continues to generate output until you enter the
no form of the command.
If you enable a
debug command and no output appears, consider these possibilities:
The switch might not be properly configured to generate the type of traffic you want to monitor. Use the
show running-config command to check its configuration.
Even if the switch is properly configured, it might not generate the type of traffic you want to monitor during the particular period that debugging is enabled. Depending on the feature you are debugging, you can use commands such as the TCP/IP
ping command to generate network traffic.
To disable debugging of SPAN, enter this command in privileged EXEC mode:
Switch# no debug span-session
Alternately, in privileged EXEC mode, you can enter the
undebug form of the command:
Switch# undebug span-session
To display the state of each debugging option, enter this command in privileged EXEC mode:
Switch# show debugging
Beginning in privileged EXEC mode, enter this command to enable all-system diagnostics:
Switch# debug all
Because debugging output takes priority over other network traffic, and because the
debug all privileged EXEC command generates more output than any other
debug command, it can severely diminish switch performance or even render it unusable. In virtually all cases, it is best to use more specific
debug commands.
no debug all privileged EXEC command disables all diagnostic output. Using the
no debug all
command is a convenient way to ensure that you have not accidentally left any
debug commands enabled.
By default, the network server sends the output from
debug commands and system error messages to the console. If you use this default, you can use a virtual terminal connection to monitor debug output instead of connecting to the console port.
Possible destinations include the console, virtual terminals, internal buffer, and UNIX hosts running a syslog server. The syslog format is compatible with 4.3 Berkeley Standard Distribution (BSD) UNIX and its derivatives.
Note Be aware that the debugging destination you use affects system overhead. Logging messages to the console produces very high overhead, whereas logging messages to a virtual terminal produces less overhead. Logging messages to a syslog server produces even less, and logging to an internal buffer produces the least overhead of any method.
For more information about system message logging, see
You can display the physical path that a packet takes from a source device to a destination device by using one of these privileged EXEC commands:
tracetroute mac
[ interface
interface-id ] { source-mac-address } [ interface
interface-id ] { destination-mac-address } [ vlan
vlan-id ] [ detail ]
tracetroute mac ip
{ source-ip-address | source-hostname }{ destination-ip-address | destination-hostname } [ detail ]
For more information, see the command reference for this release.
You can check the physical or operational status of an SFP module by using the
show interfaces transceiver privileged EXEC command. This command shows the operational status, such as the temperature and the current for an SFP module on a specific interface and the alarm status. You can also use the command to check the speed and the duplex settings on an SFP module. For more information, see the
show interfaces transceiver command in the command reference
for this release.
The output from the
show platform forward privileged EXEC command provides some useful information about the forwarding results if a packet entering an interface is sent through the system. Depending upon the parameters entered about the packet, the output provides lookup table results and port maps used to calculate forwarding destinations, bitmaps, and egress information.
Most of the information in the output from the command is useful mainly for technical support personnel, who have access to detailed information about the switch application-specific integrated circuits (ASICs). However, packet forwarding information can also be helpful in troubleshooting.
This is an example of the output from the
show platform forward command on port 1 in VLAN 5 when the packet entering that port is addressed to unknown MAC addresses. The packet should be flooded to all other ports in VLAN 5.
Switch# show platform forward gigabitethernet1/1 vlan 5 1.1.1 2.2.2 ip 13.1.1.1 13.2.2.2 udp 10 20
Global Port Number:24, Asic Number:5
Src Real Vlan Id:5, Mapped Vlan Id:5
Lookup Key-Used Index-Hit A-Data
InptACL 40_0DD_A0000 01FFA
L2Local 80_00 00C71 0000002B
Station Descriptor:, DestIndex:0239, RewriteIndex:F005
==========================================
Egress:Asic 2, switch 1
Output Packets:
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_0DD_A0000 01FFE
Port Vlan SrcMac DstMac Cos Dscpv
Gi1/1 01.02.0002
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_0DD_A0000 01FFE
Port Vlan SrcMac DstMac Cos Dscpv
Gi1/1 01.02.0002
------------------------------------------
&output truncated&
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_0DD_A0000 01FFE
Packet dropped due to failed DEJA_VU Check on Gi1/0/2
Packet dropped due to failed DEJA_VU Check on Gi1/2
This is an example of the output when the packet coming in on port 1 in VLAN 5 is sent to an address already learned on the VLAN on another port. It should be forwarded from the port on which the address was learned.
Switch# show platform forward gigabitethernet1/1 vlan 5 1.1.1 .0145 ip 13.1.1.1 13.2.2.2 udp 10 20
Global Port Number:24, Asic Number:5
Src Real Vlan Id:5, Mapped Vlan Id:5
Lookup Key-Used Index-Hit A-Data
InptACL 40_0DD_A0000 01FFA
L2Local 80_A00 97
Station Descriptor:F0050003, DestIndex:F005, RewriteIndex:0003
==========================================
Egress:Asic 3, switch 1
Output Packets:
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_0DD_A0000 01FFE
Port Vlan SrcMac DstMac Cos Dscpv
interface-id 01.A8.0145
This is an example of the output when the packet coming in on port 1 in VLAN 5 has a destination MAC address set to the router MAC address in VLAN 5 and the destination IP address unknown. Because there is no default route set, the packet should be dropped.
Switch# show platform forward gigabitethernet1/1 vlan 5 1.1.1 03.e319.ee44 ip 13.1.1.1 13.2.2.2 udp 10 20
Global Port Number:24, Asic Number:5
Src Real Vlan Id:5, Mapped Vlan Id:5
Lookup Key-Used Index-Hit A-Data
InptACL 40_0DD_A0000 01FFA
L3Local 00_202 010F0
L3Scndr 12_0DD_A 000C001D_
Lookup Used:Secondary
Station Descriptor:, DestIndex:0226, RewriteIndex:0000
This is an example of the output when the packet coming in on port 1 in VLAN 5 has a destination MAC address set to the router MAC address in VLAN 5 and the destination IP address set to an IP address that is in the IP routing table. It should be forwarded as specified in the routing table.
Switch# show platform forward gigabitethernet1/1 vlan 5 1.1.1 03.e319.ee44 ip 110.1.5.5 16.1.10.5
Global Port Number:24, Asic Number:5
Src Real Vlan Id:5, Mapped Vlan Id:5
Lookup Key-Used Index-Hit A-Data
InptACL 40_A_A0000 01FFA
L3Local 00_A05 010F0
L3Scndr 12_A_A 00000
Lookup Used:Secondary
Station Descriptor:F0070007, DestIndex:F007, RewriteIndex:0007
==========================================
Egress:Asic 3, switch 1
Output Packets:
------------------------------------------
Lookup Key-Used Index-Hit A-Data
OutptACL 50_A_A0000 01FFE
Port Vlan SrcMac DstMac Cos Dscpv
Gi1/2 0007 XXXX.XXXX.A8.0147
The following sections provide references related to switch administration:
Cisco IE 2000 commands
Cisco IE 2000 Switch Command Reference, 15.0(1)EY
Cisco IOS basic commands
Cisco IOS Configuration Fundamentals Command Reference
Additional troubleshooting information
Hardware Installation Guide
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.
To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu:
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.
The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools.
users can log in from this page to access even more content.
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