TECHNOLOGY GUIDE 4: Basics of Telecommunications and Networks  The Telecommunications System  Network Fundamentals  Communications Protocols 1

A Typical Telecommunications System 2

Transmission Rate and Capacity Data rate over a channel is measured as bps (bits per second), kbps, Mbps, Gbps, etc. Each type of channel has a maximum data transmission capacity, measured by Bandwidth (in kHz, MHz, or GHz). 3

Cable Communications Media Unshielded Twisted Pair (UTP) Two or more pairs of insulated copper wires twisted together to minimize electromagnetic interference (EMI) between adjacent wires Coaxial Contains a solid inner copper conductor surrounded by insulation and outer braided foil shield. It has a higher capacity than UTP Fiber-Optic Made of light-conducting glass or plastic core, surrounded by more glass, called cladding, and a tough outer sheath. It has the highest capacity, is immune to EMI, and is used mostly as backbones 4

Networking Fundamentals Three different roles: Servers Clients Peers 5

Local Area Network (LAN) Covers a small physical area; is wholly owned and maintained by the user organization 6 Switch

A Small Home LAN 7 UTP cable UTP cable

Wide Area Network (WAN) Covers a large area; requires services from a service provider (e.g., phone companies) 8 Headquarter Leased Access Line Wide Area Network Cloud Branch A Leased Access Line Leased Access Line Branch C Branch B

Communications Protocols Rules and procedures that govern computer- to-computer communications e.g., Ethernet Protocol e.g., Transmission Control Protocol/ Internet Protocol (TCP/IP) 9

Ethernet Protocol Listen before transmitting / Listen while transmitting 1. Stations 4 & 6 transmits at the same time. 2. Their signals collide. Both stations stop transmitting. 3. After a random waiting period, Station 6 transmits again. 4. Station 4 transmits after Station 6 is done. Explanation: 10