Enterasys Networks Fast Network 10 manual Crossover Wiring, 5 4 3 Rule

Crossover Wiring

A.5 CROSSOVER WIRING

Two FN10s can communicate only if the transmitter on one unit is connected to the receiver on the other unit. This reversal, or crossover function, can be implemented either in the wiring or in the device itself. When connecting FN10s, a crossover must be implemented in the wiring. Refer to Table A-3 for crossover pin assignments.

Table A-3 Crossover RJ45 Pin Assignments

FN10		FN10
1	(Tx+)	3	(Rx+)
2	(Tx-)	6	(Rx-)
3	(Rx+)	1	(Tx+)
6	(Rx-)	2	(Tx-)

A.6 5 - 4 - 3 RULE

Between any two nodes (i.e., PCs or other stations) on the network, there can be:

•Up to five segments in series

•Up to four repeaters or multi-port hubs

•Up to three populated segments (that is, segments attached to two or more PCs)*

*The remaining two segments are unpopulated; these are known as inter-repeater links or IRLs. This distinction between populated and unpopulated segments is significant for coax networks only.

NOTE

This rule is completely consistent with the IEEE 802.3 specification, and is meant only to summarize the configuration specification.

Fast Network 10 User Guide Page A-5