Introduction to Status LEDs of Ethernet and Network Devices

Device status LEDs are one of the easiest ways to mark signs of trouble on a network. The NICs, hubs, routers, and switches have these small indicators that warn users if anything is going wrong. In this article, we will examine some of the common networking device LEDs.

Ethernet Port Status LEDs

The computers connect to a network using a Cat 5/6 cable and Ethernet interface. Most Ethernet interfaces have one or two LED link indicators following them. Generally, a green LED means a good connection and a blinking green LED indicates network activity.

If the link light is not glowing, it means there is a problem with the network cable or the network itself. The switch port also has indicators. If one or both LEDs are not glowing, use a different cable. The following table illustrates most host computers’ LEDs.

Network Device Status LEDs

If you have seen the network devices hub, switch, and routers, you will notice multiple LEDs on the front of each device. These multiple LED indicators provide a quick status view for network operators and administrators.

Each port has one or two dedicated LEDs. For example, a Cisco Catalyst switch has several status LEDs that help network administrators monitor system activity, performance, and timely troubleshooting. When the switch is functioning, the status LEDs are generally glowing green, and they glow amber when there is a malfunction.

The Cisco ISRs also use status LEDs of various types to provide status information. The status LEDs also help the network administrator troubleshoot network malfunctions in a timely manner. All network devices have a unique set of LEDs.

For the descriptions of LEDs, read the device-specific documentation. The following presents the general guideline for network device LEDs, and in some cases it may be different.