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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