Communication s and Networks 1
Communications What are computer communications?
Process in which two or more computers or devices transfer data, instructions, and information notebook computer s
smart phones
servers
Web-enabled PDAs
GPS receivers desktop computers
mainframe computers set-top boxes Tablet PCs
Communications What is needed for successful communications?
Sending device — initiates instruction to transmit data, instructions, or information
Communications device — connects the sending device to the communications channel
Communications device — connects the communications channel to the receiving device
Communications channel — media on which data, instructions, or information travel
Receiving device — accepts transmission of data, instructions, or information
Uses of Computer Communications What are some uses of communications technology?
Web
Internet Instant Messaging Web Folders
Chat Rooms
E-Mail Newsgroups
Video Conferencing
FTP
Fax Machine or Computer Fax/Modem
Uses of Computer Communications What are Internet telephony and Internet printing? Internet telephony enables you to talk to other people over the Internet Sometimes called Voice over IP
Internet printing allows you to print to network printer from anywhere in the world
Uses of Computer Communications What are Web services?
Software that enables programmers to create applications that communicate with other remote computers
Uses of Computer Communications What are collaboration and groupware?
Collaboration is working with other users connected to a server
Microsoft’s NetMeeting allows collaboration
Groupware is software that allows people to share information
Uses of Computer Communications What are public Internet access points and cybercafés?
Public Internet access point allows wireless connection to Internet in public location Cybercafé is coffee house that provides computers with Internet access
Networks What is a network?
Collection of computers and devices connected via communications devices and transmission media
Networks What is a local area network (LAN)?
Network in limited geographical area such as home or office building
Metropolitan area network (MAN) connects LANs in city or town
Networks What is a wide area network (WAN)?
Network that covers large geographic area using many types of media Internet is world’s largest WAN
Networks What is a client/server network?
One or more computers act as server and other computers, or clients, access server
Networks What is a peer-to-peer network?
Simple network that connects fewer than 10 computers Each computer, or peer, has equal capabilities
Networks What is Internet peer-to-peer (P2P)? Enables users to connect to each other’s hard disks and exchange files directly
Networks What is a bus network?
All computers and devices connect to central cable, or bus Example of network topology (layout of devices in network)
Popular topologies are bus, ring, and star
Networks What is a ring network?
Cable forms closed ring, or loop, with all computers and devices arranged along ring Data travels from device to device around entire ring, in one direction
Networks What is a star network?
All devices connect to a central device, called hub All data transferred from one computer to another passes through hub
Networks What are Ethernet and token ring? Ethernet technology allows computers to contend for access to network If two computers send data at same time, a collision occurs and computers must send again
Token ring technology controls access to network by requiring devices to pass a special signal, called token
Networks What are TCP/IP and 802.11?
TCP/IP (Transmission Control Protocol/Internet Protocol) technology transmits data by breaking it up into small pieces, or packets
Commonly used for Internet transmissions
802.11 is family of standards for wireless LANs
Networks What is Bluetooth?
Short-range radio waves transmit data between Bluetooth devices
Networks What are IrDA, RFID, and Wireless Applications Protocol (WAP)? Radio RadioFrequency Frequency Identification Identification(RFID) (RFID) IrDA IrDA
specification specificationallows allows data datatotobe betransferred transferred wirelessly wirelesslyvia viainfrared infrared light lightwaves waves
uses usesradio radiosignals signalstotocommunicate communicate with withaatag tagplaced placedininan anobject object
Wireless WirelessApplications Applications Protocol Protocol(WAP) (WAP)
allow allowwireless wirelessmobile mobiledevices devices totoaccess accessInternet Internet
Networks What is an intranet?
Internal network that uses Internet technologies Makes information accessible to employees Typically includes connection to Internet Extranet allows customers or suppliers to access part of company’s intranet