TDHSS Networkingorg

8/9/2019 TDHSS Networkingorg

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` A network is a collection of computers connected

to each other. The network allows computers to

communicate with each other and share resources

and information. The Advance Research Projects Agency (ARPA) designed "Advanced Research

Projects Agency Network" (ARPANET) for the

United States Department of Defense. It was the

first computer network in the world in late 1960'sand early 1970's.


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` Resource Sharing

` Data Sharing

` Communication

` Security` Expanded Computer Usage


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` Based on their scale, networks can be classified

as Local Area Network (LAN), Wide Area Network

(WAN), Metropolitan Area Network (MAN),

Personal Area Network (PAN),Virtual PrivateNetwork (VPN) etc.


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` Computer networks can also be classified

according to the hardware and software

technology that is used to interconnect the

individual devices in the network, such as Opticalfiber, Ethernet, Wireless LAN


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` Computer networks may be classified according to

the functional relationships which exist among the

elements of the network, e.g., Active Networking,

Client-server and Peer-to-peer (workgroup)architecture.


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` Computer networks may be classified according to

the network topology upon which the network is

based, such as Bus network, Star network, Ring

network, Mesh network, Star-bus network, Tree orHierarchical topology network.


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Personal Area Network (PAN)

Local Area Network (LAN)

Campus Area Network (CAN)

Metropolitan Area Network (MAN)

Wide Area Network (WAN)

Internetwork

Intranet

Extranet

Internet


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` A personal area network (PAN) is a computer

network used for communication among computer

devices close to one person. Some examples of

devices that are used in a PAN are printers, faxmachines, telephones, PDAs and scanners.


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` This is a network covering a small geographic

area, like a home, office, or building. Current LANs

are most likely to be based on Ethernet

technology.

` Wired LAN

` Wireless LAN


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` This is a network that connects two or more LANs

but that is limited to a specific and contiguous

geographical area such as a college campus,

industrial complex, office building, or a militarybase. A CAN may be considered a type of MAN

(metropolitan area network), but is generally

limited to a smaller area than a typical MAN


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` A Metropolitan Area Network is a network that

connects two or more Local Area Networks or

Campus Area Networks together but does not

extend beyond the boundaries of the immediatetown/city. Routers, switches and hubs are

connected to create a Metropolitan Area Network.


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` A WAN is a data communications network that

covers a relatively broad geographic area (i.e. one

city to another and one country to another country)

and that often uses transmission facilities providedby common carriers, such as telephone

companies.


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` Any interconnection among or between public,

private, commercial, industrial, or governmental

networks may also be defined as an internetwork.

` Intranet

` Extranet

` Internet


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` An intranet is a set of networks, using the Internet

Protocol and IP-based tools such as web

browsers and file transfer applications, that is

under the control of a single administrative entity.


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` An extranet is a network or internetwork that is

limited in scope to a single organization or entity

but which also has limited connections to the

networks of one or more other trusted organizationor entities.


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` The Internet is a specific internetwork. It consists

of a worldwide interconnection of governmental,

academic, public, and private networks based

upon the networking technologies of the InternetProtocol Suite. The Internet is also the

communications backbone underlying the World

Wide Web (WWW).


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Point-to-point

Bus

Star

Ring

Mesh

Tree


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` The simplest topology is a permanent link

between two endpoints. Switched point-to-point

topologies are the basic model of conventional

telephony. The value of a permanent point-to-pointnetwork is the value of guaranteed, or nearly so,

communications between the two endpoints


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` Linear bus` The type of network topology in which all of the

nodes of the network are connected to a common

transmission medium

` Distributed bus

` The type of network topology in which all of the

nodes of the network are connected to a common

transmission medium which has more than two

endpoints that are created by adding branches tothe main section of the transmission medium


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` The type of network topology in which each of the

nodes of the network is connected to a central

node with a point-to-point link in a 'hub' and

'spoke' fashion, the central node being the 'hub'and the nodes that are attached to the central

node being the 'spokes'


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` The type of network topology in which each of the

nodes of the network is connected to two other

nodes in the network and with the first and last

nodes being connected to each other, forming aring


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` The value of fully meshed networks is proportional

to the exponent of the number of subscribers,

assuming that communicating groups of any two

endpoints, up to and including all the endpoints, isapproximated by Reed's Law.

` Full Fully connected


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` The type of network topology in which a central'root' node (the top level of the hierarchy) is

connected to one or more other nodes that are

one level lower in the hierarchy (i.e., the second

level) with a point-to-point link between each ofthe second level nodes and the top level central

'root' node, while each of the second level nodes

that are connected to the top level central 'root'

node will also have one or more other nodes thatare one level lower in the hierarchy (i.e., the third

level) connected to it


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Network Interface Cards

Repeaters

Hubs

BridgesSwitches

Routers


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` A network card, network adapter or NIC

(network interface card) is a piece of computer

hardware designed to allow computers to

communicate over a computer network. Itprovides physical access to a networking medium

and often provides a low-level addressing system

through the use of MAC addresses. It allows users

to connect to each other either by using cables or

wirelessly. The NIC provides the transfer of data in

megabytes.


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` A repeater is an electronic device that receives a

signal and retransmits it at a higher power level, or

to the other side of an obstruction, so that the

signal can cover longer distances withoutdegradation. In most twisted pair ethernet

configurations, repeaters are required for cable

runs longer than 100 meters away from the

computer.


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` A hub contains multiple ports. When a packet

arrives at one port, it is copied to all the ports of

the hub for transmission. When the packets are

copied, the destination address in the frame doesnot change to a broadcast address.


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` A network bridge connects multiple network

segments at the data link layer (layer 2) of the OSI

model. Bridges do not promiscuously copy traffic

to all ports, as hubs do, but learn which MACaddresses are reachable through specific ports.

Once the bridge associates a port and an address,

it will send traffic for that address only to that port.

Bridges do send broadcasts to all ports except the

one on which the broadcast was received.


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` A switch is a device that performs switching.

Specifically, it forwards and filters OSI layer 2

datagrams (chunk of data communication)

between ports (connected cables) based on theMAC addresses in the packets. This is distinct

from a hub in that it only forwards the datagrams

to the ports involved in the communications rather

than all ports connected.


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` Routers are networking devices that forward data

packets between networks using headers and

forwarding tables to determine the best path to

forward the packets.


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` Twisted pair cables were first used in telephone

systems by Alexander Graham Bell in 1881.


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` Coaxial cable is a cable consisting of an inner

conductor, surrounded by a tubular insulating layer

typically made from a flexible material with a high

dielectric constant, all of which is then surrounded

by another conductive layer (typically of fine

woven wire for flexibility, or of a thin metallic foil),

and then finally covered again with a thin

insulating layer on the outside.


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` An optical fiber(orfibre) is a glass or plastic fiber

that carries light along its length. Fiber optics is

the overlap of applied science and engineering

concerned with the design and application of

optical fibers. Optical fibers are widely used in

fiber-optic communications, which permits

transmission over longer distances and at higher

data rates than other forms of communications


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The Domain Name System (DNS) is a

hierarchical naming system for computers,

services, or any resource participating in

the Internet. It associates variousinformation with domain names assigned

to such participants

Domain Name System


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` Dynamic Host Configuration Protocol (DHCP)

is a protocol used by networked devices (clients)

to obtain the parameters necessary for operation

in an Internet Protocol network.


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` An Internet Protocol (IP) address is a numerical

identification (logical address) that is assigned to

devices participating in a computer network

utilizing the Internet Protocol for communication

between its nodes. Although IP addresses are

stored as binary numbers, they are usually

displayed in human-readable notations, such as

192.168.100.1 (for IPv4), and

2001:db8:0:1234:0:567:1:1 (for IPv6).


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` Domain , a common network name under which a

collection of network devices that are organized.

Eg: Computers, hub, Switches, routers


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` Active Directory is a directory service used to

store information about the network resources

across a domain and also centralize the network.


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` Protocols are a set of rules and conventions

followed by systems that communicate over a

network.

` FTP

` HTTP

` TCP/IP

` TELNET` UDP


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` File Transfer Protocol (FTP) is a network

protocol used to transfer data from one computer

to another through a network


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` Hypertext Transfer Protocol (HTTP) is a

communications protocol. Its use for retrieving

inter-linked text documents (hypertext) led to the

establishment of the World Wide Web.


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` The Internet Protocol Suite (commonly TCP/IP)

is the set of communications protocols used for

the Internet and other similar networks. It is

named from two of the most important protocols in

it: the Transmission Control Protocol (TCP) and

the Internet Protocol (IP), which were the first two

networking protocols defined in this standard.


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` Telnet (Telecommunication network) is a network

protocol used on the Internet or local area network

(LAN) connections.

` Telnet provides access to a command-line

interface on a remote machine.


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` User Datagram Protocol (UDP) is one of the

core protocols of the Internet Protocol Suite. Using

UDP, programs on networked computers can send

short messages sometimes known as datagrams

(using Datagram Sockets) to one another. UDP is

sometimes called the Universal Datagram

Protocol.


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Application server

Database server

File Server

Print server

Proxy server


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` An application server, in an n-tier architecture, is

a server that hosts an API to expose business

logic and business processes for use by third-

party applications.


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` A database server is a computer program that

provides database services to other computer

programs or computers, as defined by the client-

server model.


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` A file server is a computer attached to a network

that has the primary purpose of providing a

location for the shared storage of computer files

(such as documents, sound files, photographs,

movies, images, databases, et cetera) that can be

accessed by the workstations that are attached to

the computer network.


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` A print server, orprinter server, is a computer or

device that is connected to one or more printers

and to client computers over a network, and can

accept print jobs from the computers and send the

jobs to the appropriate printers.


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` A proxy serveris a server (a computer system or

an application program) that services the requests

of its clients by forwarding requests to other

servers.


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` Internet Connection Sharing (ICS) is the name

given by Microsoft to a feature of its Windows

operating system (as of Windows 98 Second

Edition and later) for sharing a single Internet

connection on one computer between other

computers on the same local area network. It

makes use of DHCP and Network address

translation (NAT).


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` The Open Systems Interconnection Basic

Reference Model (OSI Reference Model orOSI

Model) is an abstract description for layered

communications and computer network protocol

design. It was developed as part of the Open

Systems Interconnection (OSI) initiative.


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` The Physical Layeris the first level in the seven-

layer OSI model of computer networking. It

translates communications requests from the Data

Link Layer into hardware-specific operations to

effect transmission or reception of electronic

signals.


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` The Data Link Layer provides the functional and

procedural means to transfer data between

network entities and to detect and possibly correct

errors that may occur in the Physical Layer.


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` The Network Layer provides the functional and

procedural means of transferring variable length

data sequences from a source to a destination via

one or more networks, while maintaining the

quality of service requested by the Transport

Layer. The Network Layer performs network

routing functions, and might also perform

fragmentation and reassembly, and report delivery

errors.


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` The Transport Layer provides transparent transfer

of data between end users, providing reliable data

transfer services to the upper layers. The

Transport Layer controls the reliability of a given

link through flow control, segmentation/

desegmentation, and error control.


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` The Session Layer controls the

dialogues/connections (sessions) between

computers. It establishes, manages and

terminates the connections between the local and

remote application.


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` The Presentation Layer establishes a context

between Application Layer entities, in which the

higher-layer entities can use different syntax and

semantics, as long as the Presentation Service

understands both and the mapping between them.

The presentation service data units are then

encapsulated into Session Protocol Data Units,

and moved down the stack.


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` The application layer is the OSI layer closest to

the end user, which means that both the OSI

application layer and the user interact directly with

the software application. This layer interacts with

software applications that implement a

communicating component.


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