This section discusses the distance limitations of the different types of cabling as well as the guidelines for using Ethernet and Fast Ethernet.
Critical Information

Half-duplex Ethernet has been around a long time. Ethernet came out in 1984 and is still the most popular of all LAN topologies. When a station is sending to another station, the transmitting circuitry is active at the transmitting station and receiving station is also active. This circuitry uses a single cable similar to a narrow, one-way bridge.

Full-duplex Ethernet switch technology, which we have discussed throughout this chapter, provides a point-to-point connection between the transmitter of the transmitting station and the receiver of the receiving station. With half-duplex circuitry, standard Ethernets can usually provide only 50 to 60 percent of the bandwidth available. In contrast, full-duplex Ethernets can provide a full 100 percent, because they can transmit and receive simultaneously, and because collisions don’t occur.

In order to run a full-duplex Ethernet, you must have the following:
Two 10Mbps or 100Mbps paths
Full-duplex NICs
Loopback and collision detection disabled
Software drivers supporting two simultaneous data paths
Adherence to Ethernet distance standards
Understanding the difference between the different media access speeds that Ethernet provides is important. The EIA/TIA specifies that Ethernet use a registered jack connector with a 45 wiring sequence (RJ-45) on unshielded twisted-pair (UTP) cabling. The following points outline the different Ethernet media requirements for Gigabit Ethernet:

• 1000BaseCX: Copper shielded twisted-pair that can run only up to 25 meters before losing signal strength
• 1000BaseT: Category 5 or 6 cable, using four-pair UTP wiring, up to 100 meters
• 1000BaseSX: Multimode fiber using 62.5- and 50-micron core, uses a 780-nanometer laser, up to 260 meters
• 1000BaseLX: Single-mode fiber that uses a nine-micron core, 1300-nanometer laser, up to 10 kilometers

Related posts:

1. Fast Ethernet Distance Limitations
2. Full and Half-Duplex Ethernet Operation
3. Features and Benefits of Fast Ethernet
4. Full and Half-Duplex Ethernet
5. Network Congestion Problem in Ethernet Networks
6. key Frame Relay Terms and Features
7. TCP-IP Network-layer protocol
8. key Frame Relay Terms and Features Exam Points
9. Virtual LANs
10. Configure IP addresses Exams Points