In information technology, a network is a series of points or nodes interconnected by communication...
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Transcript of In information technology, a network is a series of points or nodes interconnected by communication...
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What is a Network?
In information technology, a network is a series of points or nodes interconnected by
communication paths.
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In a network, a node is a connection point. In general, a node has programmed or engineered capability to recognize and process or forward transmissions to other nodes.
What is a Node?
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A network is an interconnected system of things or people◦ Religions◦ Business contacts◦ Snail Mail◦ Social Media◦ Broadcasting - NBC, CBS, ABC, PBS◦ Transportation (highways & rail)◦ Cellular phone service◦ …and of course computer based (internet)
Generally speaking . . .
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What is the Internet?
The Internet is a worldwide system of computer networks - a network of networks in which users at any one computer can, if
they have permission, get information from any other computer.
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Intranet◦ An organizations restricted computer network ◦ Private, yet using WWW software
Extranet◦ Part of a organization‘s intranet that is extended
to users outside the organization – usually via WWW.
◦ Customer access Internet
◦ A worldwide computer network using TCP/IP protocol to transmit and exchange data. (TCP/IP is a set of communication protocols used by
networks.)
Types of Computer Networks
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Simultaneous Access◦ Software/Programs◦ Data
Device Sharing◦ Printers◦ NAS – Network Access Storage
Communication◦ Email◦ VOIP – Voice over internet protocol (Skype)
Archiving◦ Backups of multiple clients by a single server
Computer Networks – Benefits
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In communication networks, a topology is a usually schematic description of the arrangement of a network, including its nodes and connecting lines. There are two ways of defining network geometry: the physical topology and the logical (or signal) topology.
What is Topology?
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Topologies◦ Physical connectivity
Nodes and Addressing Geographical Distribution
◦ Where are the nodes? Work Load
◦ Server networks use the nodes to disperse the workload
Computer Networks – Categorized
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Network topology is the physical interconnections of the elements (Links, Nodes, Clients, etc.) of a computer network
Main Types◦ Star◦ Bus◦ Ring◦ Wireless◦ Hybrid
Computer Networks - Topology
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Star Topology
Star topology is the most common topology used in today’s workplace.
North Greenville University in Tigerville uses star topology.
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Bus topology is where in a computer network, a bus is a transmission path on which signals are dropped off or picked up at every device attached to the line. WAP (wireless access points) are not necessary needed.
Bus Topology
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Ring Topology
A ring is a network topology or circuit arrangement in which each device is attached along the same signal path to two other devices, forming a path in the shape of a ring.
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Wireless TopologyA wireless Internet service provider (WISP) is an Internet service provider (ISP) that allows subscribers to connect to a server at designated hot spots (access points) using a wireless connection such as Wi-Fi.
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Standards – IEEE 802.11◦ 802.11a◦ 802.11b◦ 802.11g◦ 802.11n
802.11n has a higher frequency and transmits fastest and the longest range
Wireless - 802.11 is an evolving family of specifications for wireless local area networks (WLANs). There are several specifications in the family and new ones are occasionally added.
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Coax cable is the kind of copper cable used by cable TV companies between the community antenna and user homes and businesses.◦ Benefit is one wire for all
computers
Cabling - Wired
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Cabling - Wired
Ethernet twisted pair cable is faster than Wireless and is very commonly used in businesses
Ethernet is the most widely-installed local area network (LAN) technology.◦ One wire per node/client
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Fiber optic (or "optical fiber") refers to the medium and the technology associated with the transmission of information as light impulses along a glass or plastic wire or fiber.
Cabling - Wired
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Types◦ WIMAX (Worldwide Interoperability for Microwave
Access)◦ Satellite (Dish Network/Direct TV)
High transmission rate (has to be) & latency
Each node needs antenna to connect◦ Low frequency – reliable but slower transmission◦ High frequency – less reliable but higher speed
transmission
Cabling - Wireless
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Fiber is the fastest - pricey
Ethernet twisted pair – cheaper and faster
COAX – still needed
Wireless – price greater than Ethernet twisted pair
Cabling – Which is best
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Node – Client◦ Printers◦ Desktops◦ Laptops◦ Copiers◦ Network storage devices◦ Routers◦ Anything that can connect to a network
Cell phone GPS device IPOD/PSP/XBOX/PS3/Tivo/DVR/Slingbox…
Computer Networks – Nodes
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How does the network identify a node?◦ NIC MAC address – every node’s is unique
Format: 01-23-45-67-89-ab, 01:23:45:67:89:ab Each vendor has a pool of addresses
Linksys D-Link Etc.
Hardware address Translated into a software address (IP address)
Two standards for Internet Protocol (IP) IP V4 IP V6
Computer Networks – Addressing
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IP Addresses◦ IP addresses are four octets of the form and range
(0-255).(0-255).(0-255).(0-255)◦ Data is routed between nodes based on IP addresses◦ Each domain name translates to a unique IP address
www.google.com translates to 208.67.217.231 i.e. try Ping www.google.com from DOS prompt
ICANN.org is in charge of DNS Maintains Internic.org to provide info about domain names
◦ A profound shortage of addresses with IP V4 4.3 billion addresses with some reserved Usefulness of static addresses How many nodes in the world?
Computer Networks – Addressing IP V4
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IP Addresses◦ Addresses structure:(8 groups of 4 base16 digits)
2001:0db8:85a3:0000:0000:8a2e:0370:7334 ◦ Version 6 provides enough addresses for every
atom in the universe - provided they buy a computer
◦ Supports 2128 (about 3.4×1038) addresses.◦ Currently used at main WWW routing points◦ Advantages of having your own address?
Your are known wherever your node physically resides
Computer Networks – Addressing IP V6
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LAN – Local Area Network◦ Ex. – NGU
VLAN – Virtual LAN (act as a LAN due to common set of needs - collaboration)
MAN – Metropolitan Area Network◦ Ex. - City of Greenville
WAN – Wide Area Network◦ Ex. – Internet
Computer Networks – Geography
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Server Based◦ Thin client - relies heavily on server processing◦ Ex. – NGU email server
Client Server Based◦ Fat client – shares in the work load with less
expensive server◦ Ex. – NGU CAMS (clients process the reports)
Peer to Peer Based◦ Each computer can act as client or server◦ Ex. - Home network
Computer Networks – Workload
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All networks◦ Authentication
User name and password◦ Encryption
https – encrypts credit card account #s, email◦ Firewall Software
What can network users get to on your machine◦ Anti-virus Software
Protect against malware Vendors – McAfee, Symantec, AVG, etc…
◦ Finger Print Scanner◦ Contingency planning – what if the unexpected
happens Backups, backups, backups
Computer Network Security
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Wireless◦ WEP – Wired Equivalency Protocol
NOT secure (Google “breaking wep encryption”)◦ WPA – Wireless Protected Access
WPA & WPA2 – secure provided you use good pass phrases
Computer Network Security
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What do we transmit/exchange?◦ Text
Emails Print jobs Chat
◦ Graphics Pictures
◦ Video Movies Live Streaming
◦ Audio Songs Voice
Computer Network Data Transmission
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How is it transmitted?◦ Broken into packets
Header – Packet 1 Trailer – Last Packet Those in between
◦ Not all packets take the same route◦ Reassembled on receipt to match that sent
Who owns the internet?◦ Many companies – Sprint, Verizon, Time-Warner,
etc. We’re just renting space
Computer Networks – Data Transmission
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◦ Transmission is not perfect Must have schemes for re-sending dropped packets
What about audio & video – is there any reason to re-send?
What about your debit card atm transmission Easier to resend the whole thing or just what’s missing?
Computer Networks – Data Transmission
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TCP/IP – Transmission Control Protocol/Internet Protocol◦ Standard network data exchange
protocol(standard)◦ TCP applications
FTP – File transfer protocol (transfer files) Telnet – Terminal connections SMTP – email transmission POP3 – email transmission
◦ IP applications HTTP – Hypertext transfer protocolVOIP – Voice over IP
Network protocols
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ISP – Internet service provider◦ Types of connection for the home
Cable Modem DSL Modem ISDN Modem 56K Dial-up Modem Home satellite
◦ Types of connection for business Cable Modem – higher capacity than home DSL Modem – “ “ “ DS1/T1 High speed line (DS3 /T3 even better) Satellite
◦ Businesses concerned with throughput◦ Become a node on ISP’s network
Internet - Connections
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Domains◦ Common
.com, .net, .org, .edu, .gov◦ Not so common
.uk, .us, .tv, .biz, info (checkout godaddy.com) Sub Domains
◦ Part of the larger domain◦ Ex. www.ngu.blackboard.com
Domain is www.blackboard.com Sub domain is ngu
Accessed via ngu.blackboard.com
Internet - Domains
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Websites are designed using html (hypertext markup language)◦ Easy enough for anyone to create
Write html Use applications like Dreamweaver or Microsoft Expression Can save MS Office 2007 files as web pages
◦ Store cookies Ease of use User names Passwords (not so good if not secure – https)
◦ Store temporary files Faster browsing Fills up hard drive
Fragmentation
◦ Your browser will let you purge cookies and files.
Computer Networks - Websites
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Data specific Websites are encoded using XML (Extensible Markup Language)
Example – see notes Standard for data exchange
◦ MS Access can import XML Microsoft Office 2007 file naming
◦ Word “Document.docx”◦ Excel “Spreadsheet.xlsx”◦ PowerPoint “Presentation.pptx”◦ Access – “Database.accdb” ?????
Computer Networks – Data specific Websites
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http://wordnetweb.princeton.edu http://compnetworking.about.com http://en.wikipedia.org/ http://www.emailclients.net/
References