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This soft copy for use by IBM employees only.
Appendix B. Pinouts for Ports and Cables
This appendix gives information on ports and cables PIN assignments.
B.1 Pinouts for ATM25 and Other Common Network Connectors
Most networking standards have developed specifications for using shielded or
unshielded twisted-pair cabling with RJ-45 modular plugs to connect devices
together. Table 39 illustrates the differences between the following cabling
specifications:
•
ATM25.6 (ATM Forum Standard)
IBM adapters for this standard have an orange dot with a white line across it
to easily distinguish from the next two types.
•
ATM25.6 (Pre-Standard--Used by some early ATM devices)
This adapter has a green dot on it indicating that it uses standard token-ring
pinouts.
•
Token-Ring
This adapter has a green dot on it indicating that it uses standard token-ring
pinouts.
•
Ethernet (10Base-T)
Table 39. RJ-45 Pin Assignments by Network Type
Pin Number ATM25
(Forum-
Compliant)
ATM25
(Pre-Standard)
Token Ring Ethernet
(10Base-T)
1 RD+ TD+
2 RD− TD−
3 TD+ TD+ RD+
4 RD+ RD+
5 RD− RD−
6 TD− TD− RD−
7 TD+
8 TD−
B.2 Other Cabling Considerations
Special cables are required in two specific instances:
•
When connecting to pre-standard devices
•
When connecting between two ATM switches
Both of these instances are discussed below.
Copyright IBM Corp. 1996 179