Lancom Systems 1711, 821, 1621 manual Conventional network infrastructure

LANCOM 821 ADSL/ISDN – LANCOM 1621 ADSL/ISDN – LANCOM 1711 VPN

Chapter 1: Introduction

Conventional network infrastructure

First, let's have a look at a typical network structure that can be found in this form or similar forms in many companies:

LAN	EN
Head Office
LAN
Workstation in remote
access, e.g. homework
Internet
Subsidiary

The corporate network is based on the internal network (LAN) in the head- quarters. This LAN is connected to the outside world in three ways:

A subsidiary is connected to the LAN, typically using a leased line.

PCs dial into the central network via modem or ISDN connections (Remote Access Service – RAS).

The central LAN has a connection to the Internet so that its users can access the Web, and send and receive e-mail.

All connections to the outside world are based on dedicated lines, i.e. switched or leased lines. Dedicated lines are very reliable and secure. On the other hand, they involve high costs. In general, the costs for dedicated lines are dependent on the distance. Especially in the case of long-distance con- nections, keeping an eye out of cost-effective alternatives can be worthwhile.

The appropriate hardware must be available in the headquarters for every type of required connection (analog dial-up, ISDN, leased lines). In addition

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