Computer Network Technology

English for ICT

Networking what and why?Networking allows two or more computer

systems to exchange information and share resources and peripherals.

Thus, computer network helps deduces cost.

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Network ClassificationNetworks are classified according to:

Geographical area PAN, LAN, MAN, WAN

Architecture Server-based, Peer-to-peer

Topology Star, Bus, Ring

Network protocol TCP/IP, Ethernet, AppleTalk

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Geographical AreaPAN (Personal Area Network)

LAN (Local Area Network)

MAN (Metropolitan Area Network)

WAN (Wide Area Network)

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NetworkPANs include a laptop, a mobile phone, and a

PDA.

LANs are usually placed in the same building or within limited distance with each other.

MANs are networks with a maximum range of about 75 kilometers (45 miles) or so, and with high-speed transmission capabilities.

WANs have no geographical limit and may connect computers or LANs (including MANs) on opposite sides of the world.

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Network ArchitectureIn the administrative relationship between

nodes, networks can be divided into:

Server-based network

Peer-to-peer network

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Server-Based NetworkA server controls access to some resource

(i.e. harddisk, printer, etc.)

Server serves as a host for workstation connected to the server.

A workstation requests services, such as access to files or programs on the hard disk or use of a printer, from a server.

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Peer-To-Peer NetworkComputers in the network may have same

capabilities.

At one point, a given node (node A) may provide services for another node (node B).

At another time, node B may provide similar or different services for node A.

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Network TopologyTopology refers to the sahpe of a networkThere are three basic physical topologies,

including:

Star

Bus

Ring9

Star Network

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BUS

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Ring Network

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Mesh Network

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More on Physical Topologies

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Network ProtocolsProtocols are the languages or set of rules.

Computers use protocols to communicate with each other.

Networks use different protocols such as:TCP/IP, Ethernet, AppleTalk

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LANPCs in a LAN are called nodes.Nodes may be servers or workstations.Nodes are connected to a network by means

of a network interface card (NIC)Also called a network adapter card.

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Network ConnectionsWired Network

Wired Networks are linked by Ethernet cables, phone lines, and high speed fiber optic cables.

Wireless NetworkWireless networks use electromagnatic waves

such as radio waves to transmit data.

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Types of Wireless NetworkSatellites - for long distance (270 msec end-end

delay)

WiMAX - for connecting WiFi hotspots.

WiFi - for medium range distances

Bluetooth - for short distances

GSM - for mobile phones (cell-phones)18

WiMAX (Worldwide Interoperability for Microwave Access) WiMAX is a wireless communications

standard designed to provide 30 to 40 Mbps data rates (up to 1 Gbps)

Providing at-home or portable mobile broadband connectivity across cities or countries.

 Operating at the maximum range of 50 km (31 mi)

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Wireless Network (802.11)

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Cat-5 Socket and Cable

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Fiber Optic Cable

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HubA hub is a component that serves as a

common termination point for multiple nodes and that can relay signals along the appropriate paths.

A hub is a box with a number of connectors to which nodes are attached

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HUB

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HUB

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SwitchPhysically, a switch resembles a hub.

It is used to separate LAN segment.

It has higher data rate (10/100/1000 Mbps)

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Switch

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RouterA router connects two or more different

networks together.

It provides a path from a node on one network to a node on another network.

If a computer in one network would like to connect to another computer on different network, a router provides a path so that these two computers can communicate with each other.

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Router

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Wireless Access Point

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Wireless Access Point (cont)A combination of Access Point, Switch, and

Router

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Wireless Access Point (cont)

Basestation

Mobilehosts

Router

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Network Mediums

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Cat-5 Cable

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Coaxial Cable and T-Connector

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Fiber Optical Cable

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Fiber Optic Connection

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Video Tele-Conferrencing

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