Netgear FVS328 Reference Manual

C-12

Networks, Routing, and Firewall Basics

Although Ethernet networks originally used thick or thin coaxial cable, most installations currently 
use unshielded twisted pair (UTP) cabling. The UTP cable contains eight conductors, arranged in 
four twisted pairs, and terminated with an RJ45 type connector. A normal straight-through UTP 
Ethernet cable follows the EIA568B standard wiring as described in 

.

In the wiring table, the concept of transmit and receive are from the perspective of the PC. For 
example, the PC transmits on pins 1 and 2. At the hub, the perspective is reversed, and the hub 
receives on pins 1 and 2. When connecting a PC to a PC, or a hub port to another hub port, the 
transmit pair must be exchanged with the receive pair. This exchange is done by one of two 
mechanisms. Most hubs provide an uplink switch which will exchange the pairs on one port, 
allowing that port to be connected to another hub using a normal Ethernet cable. The second 
method is to use a crossover cable, which is a special cable in which the transmit and receive pairs 
are exchanged at one of the two cable connectors. Crossover cables are often unmarked as such, 
and must be identified by comparing the two connectors. Since the cable connectors are clear 
plastic, it is easy to place them side by side and view the order of the wire colors on each. On a 
straight-through cable, the color order will be the same on both connectors. On a crossover cable, 
the orange and blue pairs will be exchanged from one connector to the other.

1

Orange/White

Transmit (Tx) +

2

Orange

Transmit (Tx) -

3

Green/White

Receive (Rx) +

4

Blue

5

Blue/White

6

Green

Receive (Rx) -

7

Brown/White

8

Brown