Computer Networkspart II

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Network Types Defined

• Local area networks• Metropolitan area networks• Wide area networks

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Local Area Network (LAN)

• Series of interconnected computers, printing devices, and other computer equipment that share hardware and software resources

• Service area usually limited to a given office area, floor, or building

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Example of a LAN

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Metropolitan Area Network

• Links multiple LANs in a large city or metropolitan region

• Typically uses fiber-optic connections

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Example of a MAN

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Wide Area Network (WAN)

• Far-reaching system of networks that usually extends over 30 miles and often reaches across states and continents

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Types of Networks

InternetA wide area network that spans the planetSo, who owns the Internet?

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Internet Connections

Internet backbone A set of high-speed networks that carry Internet traffic, provided by companies such as AT&T, Verizon, GTE, British Telecom, and IBMInternet service provider (ISP) A company that provides other companies or individuals with access to the Internet

Identifying a Network Type

• Communications medium– Wire cable, fiber-optic cable, radio waves, microwaves

• Protocol– How networked data is formatted into discrete units– How each unit is transmitted and interpreted

• Topology– Physical layout of cable and logical path

• Network type– Private versus public

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Enterprise Network

• Enterprise network– Combination of LANs, MANs, or WANs that

provides users with an array of computer and network resources to complete different tasks

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Enterprise Network

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Enterprise-Wide Topologies

• Enterprise– An entire organization

• Backbone networks– Serial backbone– Distributed backbone– Collapsed backbone– Parallel backbone

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Enterprise-Wide TopologiesSerial backbone

Two or more hubs connected to each other by a single cable

Distributed backboneHubs connected to a series of central hubs or routers in a hierarchy

A simple distributed backbone network14

Enterprise-Wide Topologies

A distributed backbone connecting multiple LANs

VA GA NC

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Enterprise-Wide TopologiesCollapsed backbone

Uses a router or switch as the single central connection point for multiple subnetworks

A collapsed backbone network

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Enterprise-Wide TopologiesParallel Backbone

Collapsed backbone arrangement that consists of more than one connection from central router or switch to each network segment

A parallel backbone network17

Enterprise-Wide TopologiesMesh networks

Routers are interconnected with other routers, with at least two pathways connecting each router

An example of a mesh network18

Wide Area Network (WAN) Topologies

Peer-to-peer topologyWAN with single interconnection points for each locationDedicated circuits

Continuous physical or logical connections between two access points that are leased from a communication provider

A peer-to-peer WAN

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Wide Area Network (WAN) Topologies

Ring WAN topologyEach site is connected to two other sites so that entire WAN forms

a ring pattern

A ring-configured WAN20

Wide Area Network (WAN) Topologies

Star WAN topologySingle site acts as the central connection point for several other

points

A star-configured WAN

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Wide Area Network (WAN) Topologies

Mesh WAN topologyMany directly interconnected locations forming a complex mesh

Full-mesh and partial-mesh WANs 22

Wide Area Network (WAN) Topologies

Tiered WAN topologySites connected in star or ring formations are interconnected at different

levels, with interconnection points organized into layers

A tiered WAN topology23

Logical Topologies

• Refers to the way in which data are transmitted between nodes

• Describes the way:– Data are packaged in frames– Electrical pulses are sent over network’s physical

media

• Logical topology may also be called network transport system

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Network Architecture

• Defines how network functions at a logical level• Two primary types– Client-server– Peer-to-peer (P2P)

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Client-server Network Architecture

• Nodes are either clients or servers• Clients use services• Servers provide services– Access to shared data– E-mail– Printing– FAX

• Client software on client node cooperates with server software on server node– WWW is largest client server application

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Peer-to-Peer Network Architecture

• All nodes on the network are equal.• Any node can be both a client and a server.• Napster was an example of a P2P network used

to share MP3 files.• Windows printer and file sharing use P2P.

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