Planet FSD-803PE [5/24] Chapter 1

Chapter 1

INTRODUCTION

This chapter describes the features of the Switch and some background information about

Fast Ethernet switching technology.

Fast Ethernet Technology

The growing importance of LANs and the increasing complexity of desktop computing

applications are fueling the need for high performance networks.

A number of high-speed LAN technologies have been proposed to provide greater

bandwidth and improve client/server response times. Among them, 100Base-TX (Fast

Ethernet) provides a non-disruptive, smooth evolution from 10Base-T technology. The

non-disruptive and smooth evolution nature, and the dominating potential market base,

virtually guarantee cost effective and high performance Fast Ethernet solutions in the

years to come.

100Mbps Fast Ethernet is a standard specied by the IEEE 802.3 LAN committee. It is

an extension of the 10Mbps Ethernet standard with the ability to transmit and receive

data at 100Mbps, while maintaining the CSMA/CD Ethernet protocol. Since the 100Mbps

Fast Ethernet is compatible with all other 10Mbps Ethernet environments, it provides a

straightforward upgrade and takes advantage of the existing investment in hardware,

software, and personnel training.

Switching Technology

Another approach to pushing beyond the limits of Ethernet technology is the development

of switching technology. A switch bridge Ethernet packets at the MAC address level of

the Ethernet protocol transmitting among connected Ethernet or Fast Ethernet LAN

segments.

Switching is a cost-effective way of increasing the total network capacity available to

users on a local area network. A switch increases capacity and decreases network loading

by dividing a local area network into different segments, which don t compete with each

other for network transmission capacity.

The Switch acts as a high-speed selective bridge between the individual segments. The

Switch, without interfering with any other segments, automatically forwards trafc that

needs to go from one segment to another. By doing this the total network capacity is

multiplied, while still maintaining the same network cabling and adapter cards.

For Fast Ethernet networks, a switch is an effective way of eliminating problems of

chaining hubs beyond the two-repeater limit. A switch can be used to split parts of the

network into different collision domains, making it possible to expand your Fast Ethernet

network beyond the 205-meter network diameter limit for 100Base-TX networks. Switches

supporting both traditional 10Mbps Ethernet and 100Mbps Fast Ethernet are also ideal for

bridging between the existing 10Mbps networks and the new 100Mbps networks.

Switching LAN technology is a marked improvement over the previous generation of

network bridges, which were characterized by higher latencies. Routers have also been

10-000039-000.indd 2004/8/27, �� 05:373