3com 3CR17451-91 User Manual

Table 4 lists LEDs visible on the front of the Switch, and how to read their 
status according to color. For information on using the LEDs for problem 
solving, see “Checking for Correct Operation of LEDs” on page 23.

Table 4   LED behavior  

Green

A high speed (1000 Mbps) link is present, and the port 
is enabled.

Green flashing

A high speed (1000 Mbps) link is present and active.

Yellow

A low speed (10/100 Mbps) link is present, and the 
port is enabled.

Yellow flashing

A low speed (10/100 Mbps) link is present and active.

Green for one 
second, Amber 
for one second, 
then OFF until 
operational.

POST in operation, all LEDs perform a one second lamp 
test.

Alternate yellow 
then green 
flashing (fast) 

A port has failed a loop back test during POST.

Alternate yellow 
then green 
flashing

A link is present but the port has been disabled.

Off

No link is present.

Green

The uplink/downlink is operating normally.

Yellow

One-sided connection (one side of the cable is 
connected but the other side is not).

Off

No stacking link is present.

Green

Master unit - normal stack operation status.

Yellow

Slave unit - normal stack operation status.

Yellow flashing

The system is in arbitration/election status.

Off

The system is not stacked.

DUA1745-0AAA03.book  Page 13  Friday, April 8, 2005  12:34 PM