Resolving Utp Cabling Problems - IBM 5500 Operational, Installation, And Maintenance Manual

Resolving UTP Cabling Problems

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Chapter 6: Twinax Client Cabling Requirements and Problem Solving
Figure 75: Normal and Reversed Phase Designations
Designation
RJ112
Pins 2 and 5
Pins 3 and 4
RJ45
Pins 1 and 2
Pins 3 and 6
Pins 4 and 5
Note: No industry standard is assigned for designating the phase of baluns.
Other manufacturers might designate their "standard" balun to be either the
IBM "normal" or "reversed." Using baluns from other manufacturers with
IBM baluns or hubs is not recommended. If you use baluns from other
manufacturers, make sure the baluns have the same pinout and phase as the
IBM baluns and hubs.
Baluns can include internal termination. This internal termination replaces
external terminators, self-terminating Y-cables, and so on, eliminating the
need for extra components.
The examples in this section assume that all devices attached using baluns are
correctly terminated. Depending on the brand and type of the device, it can be
terminated by:
• Internal device switches
• Self-terminating Y or T cables
• Self-terminating baluns
Eliminate as many components as possible from your configuration so that
you can verify the simplest configuration.
Then, reconnect the components one at a time.
The checklist begins with the simplest configuration possible. Beginning at
the point where the systems fails, follow the steps in the checklist. If a step
fails, resolve the problem before going to the next step.
Step 1. Using a short length of twinax cable, attach the terminal directly to
the 5500 host port. If the device successfully connects, the 5500 system, the
Planning, Installation, and Maintenance Guide
Normal
Phase A Phase B
5 2
4 3
2 1
6 3
5 4
Reverse
Phase A Phase B
2 5
3 4
1 2
3 6
4 5