PABX system

This document covers the basics of how networking works, and how to use different devices to build networks. Computer networking has existed for many years, and as time has passed the technologies have become faster and less expensive. Networks are made up of various devices—computers, switches, routers—connected together by cables or wireless signals. Understanding the basics of how networks are put together is an important step in building a wireless network in a community or neighborhood.
This module covers the concepts of:

• Clients and servers—how services such as e-mail and web pages connect using networks.
• IP addresses—how devices on a network can be found.
• Network hubs, switches and cables—the hardware building blocks of any network
• Routers and firewalls—how to organize and control the flow of traffic on a network