Return to MAIN-Index  Return to SUB-Index    IBM-AUSTRIA - PC-HW-Support    30 Aug 1999

Verifying GBIC and Cable Signal Presence



Verifying GBIC and Cable Signal Presence

NOTE: Do Not look directly into any fiber cable or GBIC optical output.
To view an optical signal, use a mirror to view the reflected light.


Verifying Signal Presence: In addition to verifying port LED status, you can verify signal presence by using a mirror to look for a reflected light at the fiber-optic cable ends and the GBIC transmitter. To verify signal presence at the hub end of a link, insert a GBIC into the hub and place a mirror at the bottom of the SC connector. If a signal is present, you will see a low intensity red light in the mirror reflecting from the GBIC transmitter.

 

Verifying Node End: To verify the integrity of the fiber optic cable at the node end of a link, make sure the cable is attached to the GBIC at the hub and the hub is turned on. Dual SC fiber-optic cable connectors are keyed and will insert into a GBIC in one direction only. Place a mirror at the node end of the link. A low intensity red light is visible in the mirror reflection of one of the SC leads, as shown in the following illustration.
 

If a fiber-optic cable has good transmitter output but a broken or degraded receiver lead, the end node might sense a loop down  state
Because the transmitter is good, the hub responds to the end node valid Fibre Channel signal and adds the device to the loop. But, because the end node is not receiving Fibre Channel signals, it will stream loop-down sequences onto the loop. This prevents all data communications among the devices on the loop and will continue to do so until the condition is corrected.

Verifying Hub End: To verify the integrity of the fiber-optic cable at the hub end, make sure the fiber-optic cable is plugged into the host bus adapter at the host or into a disk-array controller and that the device is enabled on the loop. Using a mirror, examine the cable SC leads to verify that a low-intensity red light is visible on the receiver lead.

NOTE:

Some fiber optic cables are marked with an "A" on the receiver lead and a "B" on the transmitter lead and are keyed. Some multimode cables plugged into a GBIC, HBA, or disk array controller are key-oriented with the "B" lead inserted into the device transmitter. Place a mirror on the opposite end of the cable to see the low-intensity red light on the "A" receiver lead.

Back to  Jump to TOP-of-PAGE
More INFORMATION / HELP is available at the  IBM-HelpCenter

Please see the LEGAL  -  Trademark notice.
Feel free - send a Email-NOTE  for any BUG on this page found - Thank you.