Reference Manual for the Model DG814 DSL Modem Internet Gateway
B-12 Networks and Routing Basics
• Crossover cable
A crossover cable 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.
• Auto MDI/MDI-X switching
Some Ethernet switch products, such as the Model DG814 gateway, are able to sense the
polarity of a connection and automatically adapt to the proper mating polarity.
Cable Quality
A twisted pair Ethernet network operating at 10 Mbits/second (10BASE-T) will often tolerate low
quality cables, but at 100 Mbits/second (10BASE-Tx) the cable must be rated as Category 5, or
"Cat 5", by the Electronic Industry Association (EIA). This rating will be printed on the cable
jacket. A Category 5 cable will meet specified requirements regarding loss and crosstalk. In
addition, there are restrictions on maximum cable length for both 10 and 100 Mbits/second
networks.