What are my choices for high-speed networking?

Switched Ethernet | 100BASE-T | ATM | Gibabit Ethernet

Switched Ethernet relies on centralized multiport switches to provide a physical link between multiple LAN segments. Inside each intelligent 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 while reducing overall congestion, so Switched Ethernet provides superior configuration flexibility. It also gives you an excellent migration path from 10- to 100-Mbps Ethernet, since both segments can often operate via the same switch.

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 retains the familiar CSMA/CD media access technique used in 10-Mbps Ethernet networks. It also supports a broad range of cabling options: two standards for twisted pair and one for fiber. 100BASE-TX supports 2-pair Category 5 UTP or Type 1 STP cable. 100BASE-FX enables fiber optic links via duplex multimode fiber cable.

Benefits of 100BASE-T—It retains CSMA/CD, so existing network management systems don’t need to be rewritten. It can easily be integrated into existing 10-Mbps Ethernet LANs, so your previous investment is saved (see Figures 1 and 2). It’s also backed by hundreds of manufacturers in the high-speed networking industry, including Black Box!

100-Mbps Ethernet Standards
		100BASE-T (IEEE 802.3u)
Variations of this Standard		100BASE-TX 100BASE-FX
Supported Cable Type		100BASE-TX		Category 5 (2-Pair)
		100BASE-FX		Duplex Multimode or Single-Mode Fiber
Maximum Cable Segments (Hub-to-Node)		100BASE-TX		Category 5—100 m
		100BASE-FX		Multimode Fiber—2 km Single-Mode—10 km
Best Applications		Backbone using Ethernet switches to provide increased throughput. Small to medium workgroups using applications (i.e. CAD, CAM) that output huge data files.

Asynchronous Transfer Mode (ATM) is a cell-based fast-packet communication technique that supports data-transfer rates ranging from sub-T1 speeds (less than 1.544 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. Instead, 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, the signaling technology of the future, offers more predictable performance than variable-length frames. And it can be integrated into an existing network as needed without having to upgrade the entire LAN.

Like Ethernet and Fast Ethernet before it, Gigabit Ethernet works with earlier versions of the IEEE 802.3 standard—both 10 and 100 Mbps— although some equipment will need to be upgraded. The Gigabit Ethernet standard (IEEE 802.3z) was approved in June 1998, and its speed of 1 Gbps is a tenfold increase over Fast Ethernet.

There are two basic types of Gigabit Ethernet: shared and switched. Shared Gigabit Ethernet is a higher-speed version of 10/100BASE-T using CSMA/CD Medium Access Control. Switched Gigabit Ethernet uses Logical Link Control (LLC). Gigabit Ethernet increases frame sizes from 64 bytes to 512 bytes minimum, and from 1514 bytes to 9000 bytes maximum.

Benefits of Gigabit Ethernet—It solves bandwidth problems. Its primary use is for backbones. The medium is fiber or Category 5e 100-ohm cable.