Cisco Catalyst 2955 Series User manual

CHAPTER

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Troubleshooting

The front-panel LEDs provide troubleshooting information about the switch.

They show power-on self-test (POST) failures, port-connectivity problems, and

overall switch performance. For a full description of the LEDs, see the “LEDs”

section on page 2-10.

You can also get statistics from the browser interface, the command-line interface

(CLI), the Cisco Intelligence Engine 2100 (IE2100) Series Configuration

Registrar, or a Simple Network Management Protocol (SNMP) workstation. See

the switch software configuration guide, the switch command reference, or the

documentation that came with your IE2100 or SNMP application for details.

This chapter provides these topics for troubleshooting problems:

•Understanding POST Results, page 5-2

•Diagnosing Problems, page 5-3

Chapter 5 Troubleshooting

Understanding POST Results

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Understanding POST Results

After the power is connected, the switch automatically begins POST, a series of

tests that verifies that the switch functions properly.

Note The uplink port status LEDs provide system and status information during POST.

On the Catalyst 2955C-12 and 2955S-12, the uplink ports are labeled 13 and 14.

On the Catalyst 2955T-12, the uplink ports are labeled 1 and 2.

Warning

If you connect or disconnect the console cable with power applied to the

switch or any device on the network, an electrical arc can occur. This could

cause an explosion in hazardous location installations. Be sure that power is

removed or the area is nonhazardous before proceeding.

To verify switch operation, perform POST on the switch in a nonhazardous

location before installation.

Statement 1065

When the Catalyst 2955C-12 and 2955S-12 begin POST:

•Uplink port 13 LED is amber.

•Uplink port 14 LED blinks green.

When the Catalyst 2955T-12 begins POST:

•Uplink port 1 LED is amber.

•Uplink port 2 LED blinks green.

If POST completes successfully on the Catalyst 2955C-12 and 2955S-12:

•Uplink port 13 LED turns green.

•Uplink port 14 LED goes off during the flash file system initialization.

If POST completes successfully on the Catalyst 2955T-12:

•Uplink port 1 LED turns green.

•Uplink port 2 LED goes off during the flash file system initialization.

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Chapter 5 Troubleshooting Diagnosing Problems

If POST fails on the Catalyst 2955C-12 and 2955S-12:

•Uplink port 13 LED blinks amber.

•Uplink port 14 LED turns green.

If POST fails on the Catalyst 2955T-12:

•Uplink port 1 LED blinks amber.

•Uplink port 2 LED turns green.

Note The uplink port status LEDs provide system and status information during POST.

On the Catalyst 2955T-12, the uplink ports are labeled 1 and 2. On the

Catalyst 2955C-12 and 2955S-12, the uplink ports are labeled 13 and 14.

POST failures are usually fatal. Call Cisco Systems immediately if your switch

does not pass POST. See the “Obtaining Technical Assistance” section on

page xxx.

Diagnosing Problems

Common switch problems fall into these categories:

•Poor performance

•No connectivity

•Corrupted software

Chapter 5 Troubleshooting

Diagnosing Problems

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Table 5-1 describes how to detect and solve these problems.

Table 5-1 Common Problems and Solutions

Symptom Possible Cause Resolution

Poor performance or

excessive errors. Duplex autonegotiation mismatch. See the switch software

configuration guide for

information about identifying

autonegotiation mismatches.

Cabling distance exceeded.

•Port statistics show excessive

frame check sequence (FCS),

late-collision, or alignment

errors.

•See the switch software

configuration guide for

information about

displaying port statistics.

•For 10BASE-T, 100BASE-TX,

and 1000BASE-T connections:

–

The distance between the

port and the attached device

exceeds 328 feet

(100 meters).

•Reduce cable length to

within the recommended

distances.

•For 100 and 1000 speed

connections:

–

Wrong cable type (not

Cat 5) attached to device

and switch

•Replace wrong cable type

with Cat 5 cable.

–

If the switch is attached to a

repeater, the total distance

between the two end

stations exceeds the cabling

guidelines.

•See your repeater

documentation for cabling

guidelines.

Bad adapter in attached device.

•Excessive errors found in port

statistics. •Run adapter card diagnostic

utility.

Spanning Tree Protocol (STP)

checking for possible loops. Wait 30 seconds for port status

LED to turn green.

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Chapter 5 Troubleshooting Diagnosing Problems

No connectivity. Incorrect or bad cable.

No link at both ends.

•A crossover cable was used

when a straight-through was

required, or vice-versa.

•For the correct pinouts and

the proper application of

crossover vs.

straight-through cables, see

the “Cable and Adapter

Specifications” section on

page B-5.

•The cable is wired incorrectly. •Replace it with a tested

good cable.

•STP checking for possible

loops. •Wait 30 seconds for port

status LED to turn green.

Unreadable characters on

the management console. Incorrect baud rate. Reset the terminal-emulation

software to 9600 baud.

System LED (Uplink port

status 13 LED) is amber,

and all port LEDs are off.

Corrupted software. Attach a monitor to the serial

port to display the switch boot

loader. For more information,

see the switch software

configuration guide.

System LED (Uplink port

13 LED) is amber. •Fatal POST error detected. •Contact Cisco Systems.

Table 5-1 Common Problems and Solutions (continued)

Symptom Possible Cause Resolution

Chapter 5 Troubleshooting

Diagnosing Problems

5-6

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