UTP Patch Leads

(10Mb or 100Mb)

Pin designations of an RJ45 socket

The following table shows the pin allocations for 8 way twisted pair cables used for 10Base-T and 100Base-TX network connections. Note that for 1000Mb connections all four pairs are used. Refer to above diagram for pin numbering convention.

Contact	MDI-X Signal (Hub)	MDI Signal (Workstation)
1	RD+ (receive)	TD+ (transmit)
2	RD- (receive)	TD- (transmit)
3	TD+ (transmit)	RD+ (receive)
4
5
6	TD- (transmit)	RD- (receive)
7
8

Straight Cables

A straight cable is used to connect a 'workstation' to a 'hub'. All 8 connections should be wired, but only pairs 1 & 2 and 3 & 6 are used in this application.

Crossover Cables

When cascading or connecting a hub to another switch, bridge, or hub through the UTP port, a modified cable will be necessary. With a crossover cable, two pairs of wires are reversed at one connector end.

Connect wires 1 and 2 in plug A, to contacts 3 and 6 in plug B respectively.
Connect wires 3 and 6 in plug A, to contacts 1 and 2 in plug B respectively.

This is shown in the sketch below (Note wiring is identical if connecting two 'workstations' instead of two 'hubs').