BasicComputerNetwork-UniversityofCalifornia,Riverside.ppt

Basic Computer Network WeeSan Lee weesan@ Bandwidth Data rate measured in bits (not bytes) per seconds Kbps (Kilobits per seconds) 125 chars/sec Mbps (Megabits per seconds) 1,250 chars/sec Gbps (Gigabits per seconds) 12,500 chars/sec Connecting to the Internet Requirement A computer or PDA or cell phone An account with an ISP (Internet Service Provider) A modem (modulator/demodulator) for dial-up services or a NIC (Network Interface Card) for DSL/Cable services Home Network (single machine) Home Network (multiple machines) Home Network (multiple machines) Home Wireless Network Connection Types LAN WLAN Dial-up Services Broadband Services WAN LAN (Local Area Network) A network of computers that are in the same physical location, such as home or building Usually connected using Ethernet A standard on how computers communicate over a shared media (cable) LAN (Local Area Network) Ethernet Standard 10BaseT 10Mbps (Mega bits per second) 100BaseT 100Mbps 1000BaseT 1000Mbps or 1Gbps Correction from the book (pg. 10) Why do we get faster connection at work or on campus than at home? LAN (Local Area Network) Question: Can 2 computers communicate by connecting each other using an Ethernet cable back-to-back? WLAN (Wireless LAN) Wi-Fi (Wireless Fidelity) A wireless technology that connects computers without cables Access Point (AP) A device (base station) that connects wireless devices together Usually connected to a wired-network ESSID (Extended Service Set ID) A “name” for the AP, eg. mobilenet Hotspot The area covered by wireless access points WLAN (Wireless LAN) Standard 802.11b - 11Mbps 802.11g - 54Mbps 802.11a - 54Mbps Security WEP (Wired Equivalen Privacy) WPA (Wi-Fi Protected Access) To prevent wardriving Dial-up Services Modem Modulator/demodulator A device that converts analog signal to digital (modulation) and vice versa (demodulation) Speed 1200/2400/9600 bps 14.4/28.8/33.6 Kbps 56 Kbps Dial-up Services ISDN Integrated Services Digital Network 2 data channel (56K