Metro Area Networking
Detailing the technological challenges and opportunities in a lucid, humorous prose, this book lays bare the tricks and traps awaiting service providers in the metro area space.
TABLE OF CONTENTS Metro Area Networking
The Arrival of Fast Ethernet (100BaseT)
100BaseT refers to the specifications and media standards for 100 Mbps Ethernet, often called Fast Ethernet. Four standards have been defined: 100BaseTX, 100BaseFX, 100BaseT4, and 100BaseT2. Each will be discussed in this section.
All 100BaseT standards share a common MAC scheme, but each has its own unique physical-layer specification, sometimes referred to as a PHY, which usually defines the characteristics of the transceiver used in the system. The PHY can be integrated directly into a repeater or NIC, or attached externally.
100BaseTX
100BaseTX is a 100 Mbps Ethernet transmission scheme using two pairs of twisted pair, one for transmit, one for receive. A typical 100BaseTX wiring scheme uses a cable that often houses four pairs. However, because of the technology s high sensitivity to crosstalk, it is strongly recommended that the two remaining pairs be left unused. The standard supports 100-meter transmissions over 100-ohm CAT 5 UTP cable. CAT 5 is a higher-quality conductor than the CAT 3 cabling typically used with 10BaseT, and CAT 5 is rated for frequencies up to 100 MHz, while CAT 3 supports transmission up to 16 MHz.
All 100BaseTX segments are point-to-point with a single transceiver at each end of the cable. Most connections are designed to connect a computer to a hub; these hubs typically have an integrated transceiver in 100BaseTX installations.
100BaseFX
100BaseFX is a two-fiber architecture that also operates at 100 Mbps. The segment maximum length is 412 meters for half-duplex links and 2,000 meters...
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