IBM SG24-4817-00 manual Appendix B. Pinouts for Ports and Cables, Other Cabling Considerations

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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	ATM25	Token Ring	Ethernet
	(Forum-	(Pre-Standard)		(10Base-T)
	Compliant)
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