copyright©2008 n.aljaffan®ksu1 chapter 8 communications and networks

Copyright©2008 N.AlJaffan®KSU 1

Chap

ter 8

Communications and Networks


Chap

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Five general concepts provide the basis for Five general concepts provide the basis for the relationship between the the relationship between the communicating devices:communicating devices:

line configuration.line configuration.

Topology.Topology.

Network ArchitecturesNetwork Architectures

Internetworks.Internetworks.


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Line configurationLine configuration

Its refers to the way two or more communication devices attach to a Its refers to the way two or more communication devices attach to a link.link.

Link Link is the physical communication pathway that transfers data is the physical communication pathway that transfers data from one device to another.from one device to another.

There are two possible line configurationsThere are two possible line configurations

point-to-pointpoint-to-point

multipointmultipoint


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Point-to-PointPoint-to-Point

It is provides a dedicated link between two devices.It is provides a dedicated link between two devices.

The entire capacity of the channel is reserved for The entire capacity of the channel is reserved for transmission between those two devices.transmission between those two devices.


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MultipointMultipoint


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Multipoint Multipoint also called multidropalso called multidrop

It is one in which more than two specific devices It is one in which more than two specific devices share a single link.share a single link.

The capacity of the channel is shared, either The capacity of the channel is shared, either spatially or temporally.spatially or temporally.

If several devices can use the link simultaneously, it If several devices can use the link simultaneously, it is spatially line configuration. is spatially line configuration.

If users must take turns, it is a time-shared line If users must take turns, it is a time-shared line configuration. configuration.


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Topology

The term topology refers to the way a network is laid out.

There are 5 basic topologies possible: Mesh Star Tree Bus Ring


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Mesh Mesh


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Mesh Mesh

Every device has a dedicated point –to-point link to every Every device has a dedicated point –to-point link to every other device.other device.

A fully connected mesh network therefore has A fully connected mesh network therefore has n(n-1)/2n(n-1)/2 physical physical channels channels to link n devices.to link n devices.

Every device on the network must haveEvery device on the network must have n-1 n-1 input/output (I/O) portsinput/output (I/O) ports..


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Mesh Mesh

AdvantagesAdvantages1.1. Eliminating the traffic problems that can occur when links Eliminating the traffic problems that can occur when links

must be shared by multiple devices.must be shared by multiple devices.

2.2. It is robust. it one link becomes unusable, it does not It is robust. it one link becomes unusable, it does not

incapacitate the entire system.incapacitate the entire system.

3.3. It is privacy or security.It is privacy or security.

4.4. Point-to-point links make fault identification and fault Point-to-point links make fault identification and fault

isolation easy.isolation easy.


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Mesh Mesh

disadvantagesdisadvantages1.1. Installation and reconfiguration are difficult.Installation and reconfiguration are difficult.

2.2. The sheer bulk of the wiring can be greater than the The sheer bulk of the wiring can be greater than the available space can accommodate.available space can accommodate.

3.3. The hardware required to connect each link ( I/O The hardware required to connect each link ( I/O ports a cable) can be expensive.ports a cable) can be expensive.


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StarStar


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Star Star Each device (node) has a dedicated point-to-point link only Each device (node) has a dedicated point-to-point link only

to a central controller, usually called Hub.to a central controller, usually called Hub.

AdvantagesAdvantages 1.1. It is less expensive than a mesh topology. It is less expensive than a mesh topology. 2.2. It is easy to install and maintain.It is easy to install and maintain.3.3. It is robustness. If one node fails, only that node is It is robustness. If one node fails, only that node is

affected.affected.4.4. Easy fault identification and fault isolation.Easy fault identification and fault isolation.

It has one It has one disadvantagedisadvantage if the hub fails, the entire if the hub fails, the entire network is inoperable until the hub is repaired.network is inoperable until the hub is repaired.


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Tree Tree


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TreeTree Is a variation of a star.Is a variation of a star.

nodes in a tree are linked to a central hub that nodes in a tree are linked to a central hub that controls the traffic to the network.controls the traffic to the network.

Not every device plugs directly into the central hub.Not every device plugs directly into the central hub.

The majority of devices connect to a secondary hub The majority of devices connect to a secondary hub that in turn is connected to the central hub.that in turn is connected to the central hub.


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TreeTree

The central hub in the tree is an The central hub in the tree is an active hubactive hub, , which contains a repeater.which contains a repeater.

The secondary hubs may be active or passive hubs.The secondary hubs may be active or passive hubs.

A A passive hubpassive hub provides a simple physical provides a simple physical connection between the attached devices.connection between the attached devices.


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TreeTree

It allows more devices to be attached to a It allows more devices to be attached to a single central hub and can increase the single central hub and can increase the distance a signal can travel between devices.distance a signal can travel between devices.

It allow the network to isolate and prioritize It allow the network to isolate and prioritize communications from different computers.communications from different computers.


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Bus Bus


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Bus Bus Consists of a single central cable, to which all Consists of a single central cable, to which all

computers and other devices connect.computers and other devices connect.

The bus in a bus network transmits data, instruction The bus in a bus network transmits data, instruction and information in both directions.and information in both directions.

Bus network are popular on LANs because they are Bus network are popular on LANs because they are inexpensive and easy to install.inexpensive and easy to install.


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BusBus

That failure of one device usually does not affect the That failure of one device usually does not affect the rest of the bus network.rest of the bus network.

Difficult reconfiguration and fault isolation.Difficult reconfiguration and fault isolation.

A fault or break in the bus cable stops all transmission, A fault or break in the bus cable stops all transmission, even between devices on the same side of the even between devices on the same side of the problem.problem.


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RingRing


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RingRingA cable forms a closed loop (ring) with all computers and A cable forms a closed loop (ring) with all computers and

devices arranged along the ring.devices arranged along the ring.

Data transmitted on a ring network travels from Data transmitted on a ring network travels from device to device around the entire ring, in one device to device around the entire ring, in one direction.direction.

If a computer or device on a ring network fails, all If a computer or device on a ring network fails, all devices before the failed device are unaffected, but devices before the failed device are unaffected, but those after the failed device cannot function.those after the failed device cannot function.

It can span a larger distance than a bus network, It can span a larger distance than a bus network, but it is more difficult to install.but it is more difficult to install.


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Hybrid topologies Hybrid topologies

It is a network combines several It is a network combines several

topologies as subnetworks linked topologies as subnetworks linked

together in a larger topology.together in a larger topology.


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CLINET/SERVERCLINET/SERVER

PEER TO PEERPEER TO PEER

INTERNET PEER TO PEER INTERNET PEER TO PEER (P2P)(P2P)


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CLINET/SERVERCLINET/SERVER

one or more computer as a server; the other computers on the one or more computer as a server; the other computers on the

network request services from the server.network request services from the server.

Its provides an efficient means to connect 10 or more computers.Its provides an efficient means to connect 10 or more computers.

Most client/server networks require a person to serve as a network Most client/server networks require a person to serve as a network administrator because of the large size of the networkadministrator because of the large size of the network


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Network ArchitecturesNetwork Architectures PEER-TO-PEER

One type of peer-to-peer network is a simple, inexpensive network One type of peer-to-peer network is a simple, inexpensive network that typically connects fewer than10 computer.that typically connects fewer than10 computer.

1.1. Each computer, called a peer, has equal responsibilities and Each computer, called a peer, has equal responsibilities and

capabilities.capabilities.

2.2. Sharing hardware as a printer, data, or information with other Sharing hardware as a printer, data, or information with other

computers on the peer-to-peer network.computers on the peer-to-peer network.

3.3. Each computer on the network contains both the network Each computer on the network contains both the network

operating system and application software.operating system and application software.

4.4. Each computer stores files on its own storage devices.Each computer stores files on its own storage devices.


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Internet PEER-TO-PEERInternet PEER-TO-PEER ( P2P ) ( P2P )

Another type of peer-to-peer. Describe an Internet network.Another type of peer-to-peer. Describe an Internet network.

sometimes is called a sometimes is called a file sharing networkfile sharing network because users with compatible SW and an internet connection because users with compatible SW and an internet connection copy files from someone else’s HD to their HD.copy files from someone else’s HD to their HD.

exampleexample of networking SW that support P2P are BitTorrent, of networking SW that support P2P are BitTorrent, Grokster, Gunutella and Kazaa, which allow users to swap MP3 Grokster, Gunutella and Kazaa, which allow users to swap MP3 music and other files via the webmusic and other files via the web


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Categories of networks Categories of networks

Into which category a network falls is Into which category a network falls is determined its size, ownership, the distance determined its size, ownership, the distance it covers and its physical architecture.it covers and its physical architecture.

LANLAN a Local area network a Local area network

MANMAN

WANWAN


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LANLAN a Local area network a Local area network Is a network that connects computers and devices in a limited Is a network that connects computers and devices in a limited

geographical area such as a home, school computer laboratory, geographical area such as a home, school computer laboratory, office building, or closely positioned group of buildings.office building, or closely positioned group of buildings.

Is usually privately owned.Is usually privately owned.

It use only one type of transmission media (often are connected via It use only one type of transmission media (often are connected via cable ) and topology. cable ) and topology.

Wireless LANWireless LAN ( WLAN ) is a LAN that uses no physical wires. ( WLAN ) is a LAN that uses no physical wires.


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MANMAN a metropolitan area network a metropolitan area network

Is a high-speed network that connects local area network in a Is a high-speed network that connects local area network in a metropolitan area such as a city or town and handles the bulk of metropolitan area such as a city or town and handles the bulk of communications activity across that region.communications activity across that region.

MAN typically includes one or more LANs, but covers a smaller MAN typically includes one or more LANs, but covers a smaller geographic area than a WAN.geographic area than a WAN.

Its usually is managed by consortium of users or by single network Its usually is managed by consortium of users or by single network provider that sell the service to the users.provider that sell the service to the users.


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WANWAN a wide area network a wide area network

Is a network that covers a large geographic area such as country, or Is a network that covers a large geographic area such as country, or the world.the world.

Using a communications channel that combines many types of Using a communications channel that combines many types of media such as telephone lines, cables, and radio waves.media such as telephone lines, cables, and radio waves.

A WAN can be one large network or can consist of two or more A WAN can be one large network or can consist of two or more LANs connected together.LANs connected together.

The Internet is the world's largest WANThe Internet is the world's largest WAN


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InternetworksInternetworksIf 2 or more networks are connected, they become an If 2 or more networks are connected, they become an

internetwork, or internet.internetwork, or internet.

Individual networks are joined into internetworks by the use of Individual networks are joined into internetworks by the use of interworking devices.interworking devices.

These devices, which include routers and gateways.These devices, which include routers and gateways.

The termThe term internet internet should not be confused with should not be confused with InternetInternet..

internet used to mean an interconnection of networks.internet used to mean an interconnection of networks.

Internet is the name of specific worldwide network.Internet is the name of specific worldwide network.


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LANLAN

LANLAN

LANLAN

LANLAN

WAWANN

RR

RR

RR

RR

RR

RR

RR

RR

copyright©2008 n.aljaffan®ksu1 chapter 8 communications and networks

Documents

copyright2008 n

networks mesh slide

networks multipoint

networks star slide

networks pointtopoint

networks topology

networks line configuration

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