Nortel Networks NB5PLUS4/W - Manual (Page 99)

YML754 Rev1 NB5Plus4/W User Guide
www.netcomm.com.au 
Straight and crossover cable configuration
There are two types of the wiring: Straight-Through Cables and Crossover Cables.
Category 5 UTP/STP cable has eight wires inside the sheath. The wires form four
pairs. Straight-Through Cables has same pinouts at both ends while Crossover Ca-
bles has a different pin arrangement at each end.
In a straight-through cable, wires 1,2,3,4,5,6,7 and 8 at one end of the cable are
still wires 1~8 at the other end. In a crossover cable, the wires of 1,2,3,6 are re-
versed so that wire 1 become 3 at the other end of the cable, 2 becomes 6, and so
forth.
To determine which wire is wire 1, hold the RJ-45 cable tip with the spring clip
facing towards the ground and the end pointing away from you. The copper wires
exposed upwards to your view. The first wire on the far left is wire 1. You can also
refer to the illustrations and charts of the internal wiring on the following page.
Straight-Through Cabling
Figure 3
Wire Becomes
1 1
2 2
3 3
6 6
Cross-Over Cabling
Figure 4
Wire Becomes
1 3
2 6
3 1
6 2
Note: To prevent loss of signal, make sure that the length of any twisted-pair
connection does not exceed 100 metres.