Power 775 D-Link Service Procedure
PN: 41U8487, EC N44172
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APPENDIX A: BACKGROUND INFORMATION ON
FAILURE ISOLATION OF D-LINKS
The information in Section 2.11 is useful for diagnosing a link failure. This document, however, is written
with the assumption that you have already diagnosed the failure and have determined that there is a D-Link
cable needing replacement. Section 3 describes how to replace the cable.
The following procedure is used for isolating failures in D-Links, and for repairing them, if possible.
4.1.1
Likely Root Causes for Failure in D-Links
If a D-Link is found to be non-functional, there are several potential root causes. If, for example, the D-Link
from D-Port A (e.g., Hub 0, D14 in CEC drawer 0 of SN 001) to D-Port B (e.g., Hub 0, D15, in CEC drawer 0
of the SN 002) is found to be non-functional, then the possible root causes are:
1.
Failure in some part of the transmitting D-Port (e.g., connector, optical fiber ribbon, internal lenses,
optical transmitters, electrical wiring in the Hub module, or circuitry on the D-Port A Hub chip)
2.
Dirt, dust, or other contamination between the cable’s optical connector and the D-Port A internal
optical connector
3.
Breakage or failure in the D-Link cable fibers or connectors
4.
Dirt, dust, or other contamination between the cable’s optical connector and the D-Port B internal
optical connector
5.
Failure in some part of the receiving D-Port (e.g., connector, optical fiber ribbon, internal lenses,
optical receivers, electrical wiring in the Hub module, or receiver circuitry on the D-Port B Hub chip)
A failure in either the transmitting D-Port (root cause 1 above) or the receiving D-Port (root cause 5) is not
field repairable – the full CEC drawer is the Field Replaceable Unit. The procedure below is designed to
isolate whether the root cause of an D-Link failure results from failure in the transmitting or receiving CEC
drawer (1 or 5), from contamination of the connector face(s) (2 or 4), or from breakage or failure of a fiber or
a connector in the D-Link Cable (3).
In the case of a contaminated connector or connectors (case 2 or 4), the link can generally be repaired by
cleaning the connector(s). In the case of cable failure (case 3), the cable should be replaced.
4.1.2
Failure Isolation and Repair for D-Links
The following procedure is used for isolating failures in D-Links, and repairing them, if possible.
1.
Note which receiving port (D-Port B) is not receiving good signals, and which transmitting port (D-Port A) is
connected to it through the D-Link Cable, using the mapping in the system-specific System Installation Guide. Use
the following steps to determine which D-Link, and which D-Ports, are affected.
a.
Record the System Reference Code (SRC) or refcode or alert_id of the failure notification.
b.
Record the problem description or reason
c.
Record the FRU list – particularly the HFI_CAB (cable connector location code) and CBLCONT
(location code for the other end of the cable) FRUs.
d.
Before proceeding, follow the Fail-in-place (FIP) procedures to determine if action is required, since no
action is required if FIP resources are still available.
