Digital Equipment DECconcentrator 500, Installation Manual, Page: 76 / 98

Problem Solving 5–7
Table 5–4: Port Card Problem Solving
Symptom Probable Cause Corrective Action
Card Fault LED is on (red),
other Port Card LEDs off, unit
LEDs normal. Problem with the Port Card. The card needs to be replaced or re-
paired. Notify your system/network
manager or service provider.
Port LED off. Port disabled by manage-
ment, LED broken or card at
fault. Set port state on through the man-
agement software; otherwise, use the
reset to default parameter switch. Al-
ways notify your system/network
manager that you are resetting the
parameters.
Port LED blinking red. Unsupported configuration or
ring topology. Verify and reconfigure the cable con-
nections or ring topology. Before you
reconfigure, see your system/network
manager for confirmation.
Port LED red and card
fault LED on. Port broken. The card needs to be replaced or re-
paired. Notify your system/network
manager or service provider.
Port LED red and card
fault LED is off. Link Confidence Test (LCT)
failure, possible cable or
cable connection problem. Check cable connections. Run the
loopback test described in Section 5.5
to test the port. See Table 5–5 for
problem solving during loopback test-
ing.
Port LED alternates red
to green. Port is in backup state. No corrective action is required. The
backup link becomes active if the pri-
mary link fails.
5.5 Loopback Testing
Use the loopback test to determine whether the DECconcentrator 500 Port Card or
Network Management Card is faulty, or whether there’s a problem with the cable or
the device at the other end of the cable. This test verifies the ability to transmit and
receive. This test does not verify the ability to receive minimum level signals or that
the transmitter’s output level is within specification.
WARNING
!
Some fiber optic equipment can emit laser light that
can injure your eyes. Never look into an optical fiber
or connector port. Always assume the cable is con-
nected to a light source.