Troubleshooting

This chapter describes problems that could occur with the Cisco 1528 Micro Hub 10/100, possible reasons for the problems, and possible steps to take to solve the problems. The problems are grouped into states from startup to a state where the hub is up and running.

Initial Startup Problems

Table 3-1 lists problems that could occur after you connect the power cord for the first time.

Table 3-1: Initial Startup Problems

Symptom Possible Problem Possible Solutions

Power cord is connected to hub, but all LEDs, including the PWR LED, are off.

No power to hub.

Check both ends of the power cord to make certain that they are securely connected to the power receptacle on the hub and power outlet.

Make sure that the power outlet has power.

If both ends of the power cord are properly connected and the problem continues, the hub might have a faulty power supply. Contact your Cisco reseller.

Symptom	Possible Problem	Possible Solutions
Power cord is connected to hub, but all LEDs, including the PWR LED, are off.	No power to hub.	Check both ends of the power cord to make certain that they are securely connected to the power receptacle on the hub and power outlet. Make sure that the power outlet has power. If both ends of the power cord are properly connected and the problem continues, the hub might have a faulty power supply. Contact your Cisco reseller.

Problems After First Powerup

Table 3-2 lists problems that could occur after the hub powers up for the first time.

Table 3-2: Problems After Hub Powers Up

Symptom Possible Problems Possible Solutions

No link to a network device. (The front and back panel LEDs for the connecting port are off.)

One of the following cable-related problems:

Cable is not compliant with specifications.

Improperly connected cable.

Damaged cable.

Perform the following tasks in the following order:

If using a straight-through Ethernet cable, check specifications in either Table 2-1 or Table 2-2 to make sure cable you are using complies. If using a crossover Ethernet cable, check specifications in Table C-2 or Table C-3 to make sure cable you are using complies. If your cable does not comply with the specifications, that is, it is the wrong speed, wrong category, or exceeds maximum length, replace it with a cable that complies. (You can often verify the cable category by checking the marking on the outer sleeve or jacket of the cable.)

Make sure the connectors at both ends of the cable are securely seated.

To make sure you have cabled the devices correctly, refer to the sections "Connecting PCs, Workstations, Routers, or Servers," "Connecting Another Cisco 1528 Micro Hub 10/100," and "Connecting a Switch" in Chapter 2, "Installation."

Make sure the cable is not physically damaged. If it is damaged, replace it with a similar cable.

If connection to the network device is made using port 8, improperly set MDI/MDI-X button.

If the network device is connected to port 8, make sure the MDI/MDI-X button is properly set:

If using a straight-through Ethernet cable to connect a compatible PC, workstation, router, or server, the button should be OUT.

If using a straight-through Ethernet cable to connect a compatible switch, the button should be IN.

If using a straight-through Ethernet cable to connect two Cisco 1528 Micro Hub
10/100s, the button on one hub should be IN, and the button on the other hub should be OUT.

If using a crossover Ethernet cable to connect a compatible switch, the button should be OUT.

If using a crossover Ethernet cable to connect two Cisco 1528 Micro Hub
10/100s, the buttons on both hubs should be OUT.

Improperly functioning network interface card (NIC) on a PC or workstation.

Run the diagnostic supplied by the vendor on the NIC to determine if it is functioning properly. If it is not, replace it.

If the problem continues after these checks, call your Cisco reseller.

Symptom	Possible Problems	Possible Solutions
No link to a network device. (The front and back panel LEDs for the connecting port are off.)	One of the following cable-related problems: Cable is not compliant with specifications. Improperly connected cable. Damaged cable.	Perform the following tasks in the following order: If using a straight-through Ethernet cable, check specifications in either Table 2-1 or Table 2-2 to make sure cable you are using complies. If using a crossover Ethernet cable, check specifications in Table C-2 or Table C-3 to make sure cable you are using complies. If your cable does not comply with the specifications, that is, it is the wrong speed, wrong category, or exceeds maximum length, replace it with a cable that complies. (You can often verify the cable category by checking the marking on the outer sleeve or jacket of the cable.) Make sure the connectors at both ends of the cable are securely seated. To make sure you have cabled the devices correctly, refer to the sections "Connecting PCs, Workstations, Routers, or Servers," "Connecting Another Cisco 1528 Micro Hub 10/100," and "Connecting a Switch" in Chapter 2, "Installation." Make sure the cable is not physically damaged. If it is damaged, replace it with a similar cable.
	If connection to the network device is made using port 8, improperly set MDI/MDI-X button.	If the network device is connected to port 8, make sure the MDI/MDI-X button is properly set: If using a straight-through Ethernet cable to connect a compatible PC, workstation, router, or server, the button should be OUT. If using a straight-through Ethernet cable to connect a compatible switch, the button should be IN. If using a straight-through Ethernet cable to connect two Cisco 1528 Micro Hub 10/100s, the button on one hub should be IN, and the button on the other hub should be OUT. If using a crossover Ethernet cable to connect a compatible switch, the button should be OUT. If using a crossover Ethernet cable to connect two Cisco 1528 Micro Hub 10/100s, the buttons on both hubs should be OUT.
	Improperly functioning network interface card (NIC) on a PC or workstation.	Run the diagnostic supplied by the vendor on the NIC to determine if it is functioning properly. If it is not, replace it. If the problem continues after these checks, call your Cisco reseller.

Problems After Hub Is Running

Table 3-3 lists problems that could occur after the hub has been up and running for a while.

Table 3-3: Problems After Hub Is Running

Symptom Possible Problems Possible Solutions

Connection to a network device is lost. (The front and back panel LEDs for the connecting port are off.)

One of the following cable-related problems:

Disconnected cable.

Damaged cable.

Improperly functioning NIC on PC or workstation.

Make sure connectors at both ends of cable are securely seated.

Make sure the cable is not physically damaged. If it is damaged, replace it with a similar cable.

Run the diagnostic supplied by the vendor on the NIC to determine if it is functioning properly. If it is not, replace it.

If the problem continues after these checks, call your Cisco reseller.

Connection to a network device is lost. (The front panel LED for the connecting port is solid yellow.)

The hub might have automatically partitioned or separated the network device. For example, a hub could partition a network device if there are too many data collisions from the device. (For more information on data collisions, also refer to the next entry in this table.)

Run the diagnostic supplied by the vendor on the network device to determine if it is functioning properly. If it is not, replace it. If the network device is not the problem, contact your Cisco reseller.

Other than addressing the source of the problem, no action is required to bring the port out of the partitioned state. Once the port receives a valid Ethernet packet, the network device resumes communication with the rest of the network.

One of the COL/ACT LEDs is blinking yellow.

The data packets from two network devices are colliding on the network. The LED blinks faster as more collisions occur.

If one or a few collisions occur, no action is required.

If several collisions occur (the LED blinks yellow for a long time), try the following in the following order:

Check to see if any ports on connected network devices are set to full-duplex mode. If this is the case, set the network device port to half-duplex mode.

Consider further segmenting or subnetting the existing segment. Further segmenting requires another switch and separating the network devices that are transmitting a high rate of data (for example, CAD stations) on different segments.

Symptom	Possible Problems	Possible Solutions
Connection to a network device is lost. (The front and back panel LEDs for the connecting port are off.)	One of the following cable-related problems: Disconnected cable. Damaged cable. Improperly functioning NIC on PC or workstation.	Make sure connectors at both ends of cable are securely seated. Make sure the cable is not physically damaged. If it is damaged, replace it with a similar cable. Run the diagnostic supplied by the vendor on the NIC to determine if it is functioning properly. If it is not, replace it. If the problem continues after these checks, call your Cisco reseller.
Connection to a network device is lost. (The front panel LED for the connecting port is solid yellow.)	The hub might have automatically partitioned or separated the network device. For example, a hub could partition a network device if there are too many data collisions from the device. (For more information on data collisions, also refer to the next entry in this table.)	Run the diagnostic supplied by the vendor on the network device to determine if it is functioning properly. If it is not, replace it. If the network device is not the problem, contact your Cisco reseller. Other than addressing the source of the problem, no action is required to bring the port out of the partitioned state. Once the port receives a valid Ethernet packet, the network device resumes communication with the rest of the network.
One of the COL/ACT LEDs is blinking yellow.	The data packets from two network devices are colliding on the network. The LED blinks faster as more collisions occur.	If one or a few collisions occur, no action is required. If several collisions occur (the LED blinks yellow for a long time), try the following in the following order: Check to see if any ports on connected network devices are set to full-duplex mode. If this is the case, set the network device port to half-duplex mode. Consider further segmenting or subnetting the existing segment. Further segmenting requires another switch and separating the network devices that are transmitting a high rate of data (for example, CAD stations) on different segments.

When Contacting Your Cisco Reseller

Before you contact your Cisco reseller, have the following information ready:

Hub model and serial number. This information is on the back panel.
Maintenance agreement or warranty information.
Date you received the new hub.
Brief description of the problem.
Brief description of the steps you have taken to isolate the problem.

Table of Contents