Black Box compares today's popular high-speed networking options.
Switched Ethernet relies on centralised multiport switches to provide a physical link between multiple LAN segments. Inside each switch, high-speed circuitry supports wire-speed virtual connections between all the segments for maximum bandwidth allocation on demand. Adding new segments to a switch increases the aggregate network speed as it reduces overall congestion, so Switched Ethernet provides superior configuration flexibility.
Benefits of Switched Ethernet - It's a cost-effective technique for increasing the overall network throughput and reducing congestion on a 10-Mbps network. Other than the addition of the switching hub, the Ethernet network remains the same-the same network interface cards, the same client software, the same LAN cabling.
100BASE-T (IEEE 802.3u)
100BASE-T retains the familiar CSMA/CD, media-access technique used in 10-Mbps Ethernet networks and supports a range of cabling options: two standards for twisted pair, one for fibre. 100BASE-TX supports 2-pair Category 5 UTP or Type 1 STP cable. 100BASE-T4 uses 4-pair Category 3 or 4 cable. And 100BASE-FX specifies fibre optic links via duplex multimode fibre cable.
Benefits of 100BASE-T - It retains CSMA/CD so existing network management systems don't need to be rewritten. It's easy to integrate into existing 10-Mbps Ethernet LANs, so your previous investment is saved (see Figure below). It's also backed by hundreds of manufacturers in the high-speed networking industry, including Black Box!
100VG (IEEE 802.12)
100VG uses an encoding scheme called Quartet Signalling to transmit data simultaneously over all four pairs in the network cable, so it achieves a full tenfold increase in transmission speeds over 10BASE-T. It also replaces the CSMA/CD media-access control protocol with Demand Priority to optimise network operation and eliminate the overhead of packet collisions and recovery.
Benefits of 100VG - It uses a transmission frequency very similar to traditional Ethernet and works on any conventional cabling system (Category 3, 4, or 5 UTP, Type 1 STP, and fibre optics) and uses the same connectors.
Asynchronous Transfer Mode (ATM) is a cell-based fast-packet communication technique that supports data-transfer rates ranging from sub-E1 speeds (less than 2.048 Mbps) up to 10 Gbps. Like other packet-switching services (Frame Relay, SMDS), ATM achieves its high speeds in part by transmitting data in fixed-size cells and dispensing with error-correction protocols. It relies on the inherent integrity of digital lines to ensure data integrity.
Benefits of ATM - Networks are extremely versatile. An ATM network can be treated as a single network, whether it connects points in a building or across the country. Its fixed-length cell-relay operation offers more predictable performance than variable-length frames.
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