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24 MultiVOIP Gatekeeper User Guide

Introduction

This chapter documents the features and specifications for the Multi-Tech EN10100PCI (NIC board), a

10/100Mb Ethernet PCI bus NIC with Auto-negotiation (Figure 4-1).

Figure 4-1. NIC Board

About Fast Ethernet

Fast Ethernet is a network technology specified by IEEE Standard 802.3u. It extends the traditional

10Mbps Ethernet technology to achieve 100Mbps transmission and reception, while retaining the same

CSMA/CA Ethernet protocol. Thus while Fast Ethernet provides a tenfold increase in network capacity,

it is wholly compatible with traditional 10Mbps Ethernet network facilities. This compatibility is the key

to easy and efficient upgrades to 100Mbps in your network areas needing greater bandwidth.

Upgrading selected areas to Fast Ethernet does not require hardware or software changes in network

areas where traditional 10Mbps Ethernet is providing good service. For upgrading existing Ethernet

installations to 100Mbps, and especially for selectively upgrading areas needing upgrade, Fast Ethernet

is the clear choice in terms of cost-effectiveness, as well as convenience and smoothness in transition.

Fast Ethernet comprises two subtypes: 100Base-T4 and 100Base-TX. 100Base-T4 Fast Ethernet can

use existing Category 3 or Category 4 UTP network cabling, but does not provide full duplex operation.

100Base-TX requires Category 5 cabling, but does provide full duplex operation. Full duplex 100Base-

TX operation enables simultaneous transmission and reception, both at 100Mbps, thus providing

service potentially equivalent to 200Mbps half-duplex service. The EN10100PCI Adapter does not

support the 100Base-T4 subtype. To provide compatibility in traditional 10Mbps Ethernet environments

(where, for example, EN10100PCI adapters are installed anticipating upgrade of supporting hub

equipment to Fast Ethernet), the EN10100PCI also supports traditional 10 Mbps Ethernet operation, in

full-duplex as well as half-duplex modes. Selection of the best operation mode in any given installation

is automatically governed by auto-negotiation.

About Auto-negotiation

You have probably had the experience of making a dialup connection through a modem, and have

heard the gravelly-sounding exchanges between your modem and the modem at the other end of the

telephone line (these exchanges are ordinarily played out through a speaker in your local modem). As

irritating as those few seconds of noise may be, they do let you know that your modem and the remote

modem are on the job, preparing for your intended communication with the remote computer. The

preparatory work of the two modems during those few seconds before you see the Connect message

is to negotiate the best data communication scheme which is supported by both modems, and which is

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Multitech MVPGK1 Guide de l'utilisateur Page 24