Inside Twisted Pair Cables - NETGEAR ProSafe FVS114 Reference Manual

Inside Twisted Pair Cables

For two devices to communicate, the transmitter of each device must be connected to the receiver
of the other device. The crossover function is usually implemented internally as part of the
circuitry in the device. Computers and workstation adapter cards are usually media-dependent
interface ports, called MDI or uplink ports. Most repeaters and switch ports are configured as
media-dependent interfaces with built-in crossover ports, called MDI-X or normal ports. Auto
Uplink technology automatically senses which connection, MDI or MDI-X, is needed and makes
the right connection.
Figure B-4 illustrates straight-through twisted pair cable.
Figure B-4: Straight-through twisted-pair cable
Figure B-5 illustrates crossover twisted pair cable.
Figure B-5: Crossover twisted-pair cable
Network, Routing, and Firewall Basics
Reference Manual for the ProSafe VPN Firewall FVS114
202-10098-01, April 2005
B-13