IBM Books

User's Guide

Troubleshooting and Obtaining Service

Diagnosing Problems

This chapter contains procedures that help you to troubleshoot problems with your switch and its connections to other devices.

Be sure you read Appendix A, Safety Information before proceeding.

Obtaining Software

To obtain support information, including technical tips, current product information, and code updates and fixes for the switch, visit the IBM Networking Tech Support page at: 

http://www.ibm.com/networking/support

You can also subscribe to receive e-mail notifications about code updates, tips, and FAQs for your switch.

Troubleshooting in a Network

The switch terminal interface, Web interface, and SNMP management agent give you access to important statistics and other information about the network. To obtain these statistics, see Using the Terminal Interface and Using the Web Interface and select the appropriate panels.

Start of Troubleshooting Process

If one or more devices (such as workstations) connected to a switch are unable to communicate with other devices in the network, use the following steps to start the troubleshooting process:

  1. Locate the switch to which the device is connected. Use the network sketch, the label on the cable connected to the device, or other network records to help you locate the switch.
  2. Have available any documentation associated with the feature modules that are installed on the switch.
  3. If you have an EIA 232 console session set up, (see Accessing the switch), you can use it to determine if diagnostics have been completed correctly.
  4. Observe the LEDs on the front panel of the switch. The location of these LEDs is shown in Figure 3 with explanations of the LED status conditions in the accompanying table. Ignore the feature module LEDs at this time. Review this information before proceeding with the troubleshooting process.
  5. If the LED status are not OK, locate the symptom that best describes the communication problem and the LED status you observed in Table 14. Then go the section that contains the recommended actions for resolving the problem and follow that procedure.

Choosing a Troubleshooting Procedure

Use Table 14 to determine which troubleshooting procedure you should use. Unless otherwise stated, references to the OK and Fault LEDs are those on the switch.

Table 14. Troubleshooting Symptoms and Actions
Symtom and LED State Action
The Fault LED and the OK LED are Off, and the fan is not running Go to Procedure A
The Fault LED is blinking. Diagnostics are still in progress...Wait
The Fault LED is On and there is a "1" in the single-digit display. Go to Procedure E
The Fault LED is On and there is a character other than a "1" displayed in the single-digit display. Go to Procedure B
None of the devices connected to the switch can communicate, the Fault LED is Off and the Power (I) LED is On. Go to Procedure C
A single device connected to the switch is having trouble communicating. Go to Procedure D
A feature module Fault LED is On. Remove and replace the feature module.
Note:The term segment refers to a single cable or interconnected cables between a port and the device at the other end.

Procedure A

Use this procedure if all LEDs are Off:

  1. Verify that the ac power outlet to which the switch power supply is connected is active. If an uninterruptible power supply (UPS) is being used to provide ac power, ensure that the UPS is working correctly.
  2. Verify that the power cord is installed correctly.
  3. If the preceding conditions are satisfied, the power supply is defective. See Obtaining Service.

Procedure B

Use this procedure if the Fault LED is On, and there is a character other than a "1" in the single-digit display:

  1. Reset the switch by disconnecting the power cord from the outlet, waiting 10 seconds, and reconnecting the power cord to the outlet. If this corrects the problem, resume using the switch.
  2. One or more faulty feature modules can cause this symptom, and the remaining ports might continue to operate.
    1. If you have feature modules, remove them.
    2. Reset the switch.
    3. If the switch comes up, reinstall the feature modules one at a time, and reset the switch to determine the failing feature module.
  3. If the problem is not corrected, the switch is defective. See Obtaining Service.

Procedure C

Use this procedure if all devices connected to the switch are having communication problems, the Fault LED is Off and the OK LED is On:

  1. Reset the switch by disconnecting the power cord from the outlet, waiting 10 seconds, and reconnecting the power cord to the ac outlet.

Procedure D

Use this procedure if one device connected to the switch is having a communication problem, the Fault LED is Off, the OK LED is On and other attached devices can communicate through the switch:

  1. If the port LED is Off (left LED On 10/100BASE-TX port and single port LED On 100BASE-FX port):
  2. If the port Link LED is On:
    1. Go to the Port Configuration Menu. Check that the port is administratively enabled, has not been diagnostically disabled, has link up, and is in spanning tree forwarding state.
    2. Go to the Port Monitoring Menu. Check that the port is not a monitoring port.
    3. Go to the VLAN Management Menu. Check that the port is a member of the VLAN over which traffic from this device would transverse (this is usually VLAN 1). See Appendix E, Introduction to Virtual LANs (VLANs) for more details.
    4. Try pinging the attached device from another device in the same VLAN. (The switch is a member of VLAN 1; all ports are in VLAN 1 by default.)
    5. If ping is received, go to Step 5.
    6. If the ping is not received, go to Step 3.
  3. Restart the communications program on the failed connected device.
  4. For each device that is having a communication problem, connect its segment to another identically configured Ethernet port on the switch. Try each of the remaining ports to determine if the problem will go away.
  5. The problem does not appear to be in the switch and the cables and devices connected to the switch. The problem might be in the network applications or other software running on the devices that are having the communication problem. Refer to the networking software documentation for software problem determination procedures, or consult your network administrator for assistance.

Procedure E

Any port failing Power-On self test diagnostics will be "diagnostically disabled" when the switch becomes operational. Ports not failing diagnostics will be unaffected and will initialize to their configured state. This fault tolerant feature allows the switch to provide levels of connectivity even in the event of hardware failures. A quick glance at the Fault LEDs allows you to determine if the switch has diagnostically disabled any ports.

If a "1" appears in the single-digit display and any Fault LED is on solid, ports have been diagnostically disabled. If a console is connected to the switch through the EIA 232 port, a list of problem ports is printed on the console immediately after diagnostics and before entering operational code. You can also examine the Port Configuration Menu accessible from the Device Configuration Menu. Any ports with an "x" in the "STP St" column have been diagnostically disabled. To isolate this problem:

  1. Ensure that the feature modules are seated.
  2. Reset the switch.
  3. Replace any feature module if its LED is On; the feature module is defective.
  4. Replace the switch if the its Fault LED is On; the switch is defective.

Obtaining Service

There are no user-serviceable parts inside the switch chassis. All feature modules are replaceable by the user.

If you need assistance in troubleshooting or you need service for your 8275-416, call IBM at:

Refer to your IBM Warranty for information concerning service for the product, or contact the place where you purchased the product.

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