3Com 3CR990 manual Running Diagnostics, Programs, Go to Technical Support

56CHAPTER 9: TROUBLESHOOTING

■Check the connectors. Examine the cable for obvious signs of damage, wear, or crimping. Substitute a known working cable. Check the length and rating of the cable. Make sure that the cable complies with 10BASE-T or 100BASE-TX recommendations.

Go to: 10BASE-T Description.

Go to: 100BASE-TX Description.

■Check whether the NIC software is correctly installed. Go to: Verifying Successful Installation.

■If the problem persists

Go to: Technical Support.

Interpreting the LEDs The 3CR990 NICs have light-emitting diodes (LEDs) that can assist with network troubleshooting. The following table describes the LED conditions and meanings.

LED	State	Meaning
10 LNK (link)	On	If drivers are installed, the 10BASE-T connection is active.
		If drivers are not installed, the NIC is receiving power.
	Off	Something is preventing the connection between the NIC and
		the hub or switch.
100 LNK (link)	On	If drivers are installed, the 100BASE-TX connection is active.
		If drivers are not installed, the NIC is receiving power.
	Off	Something is preventing the connection between the NIC and
		the hub or switch.
ACT (activity)	Blinking	Network traffic is present.
	Steady	Heavy network traffic is present.
	Off	No network traffic is present.

	If a link LED indicates a problem, check the following:
	1 Ensure that your network hub or switch and the cable connected to your NIC
	comply with the specifications appropriate for your network connection.
	2 Ensure that the hub or switch is powered on.
Running Diagnostics	The 3CR990 NICs use two types of NIC diagnostics programs: a DOS-based
Programs	diagnostics program and a Windows-based diagnostics program.
	NOTE: Before starting any diagnostics program, close all running applications.
	Use the 3Com DOS diagnostics program if you are running any of the following
	operating systems:
	■	Windows 2000
	■	Windows NT 3.51
	■	DOS