ISYS104 Lecture Notes - Lecture 6: Ip Address, Data Element, Symmetric Digital Subscriber Line
31 May 2018
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Chapter 6- Data Communications
Q1: What is a Computer Network?
▪ Network
- Collection of computers
- Communicate with one another over transmission line
▪ Three basic types of networks
- Local area network (LAN)
- Wide area network (WAN)
- Internet
LAN (Local Area Network)
- Connected computers that reside in a single geographic location
- Single organisation location
- Within a small distance of each other (approx. 0.75 km)
- Connects between two and several hundred computers
- Organisation controls the installation of the communications media
WAN (Wide Area Network)
- Connects computers at different geographic locations
- Across metropolitan, state, regional, national areas
- Uses communication networks from vendors that are licensed by government
An Internet
- Any network of networks
- Connects LANs, WANs and other internets
- Protocol is a set of rules that two devices must follow to communicate
Q2: What are the Components of a LAN?
▪ Switch/router
- Special purpose computer that receives and transmits messages
▪ LAN device
- A switch, wireless communication device, and devices for connecting to a WAN and
via the WAN to the internet
▪ Network interface card (NIC)
- Hardare that onnets eah deie’s iruitry to the ale
▪ UTP (unshielded twisted pair) cable
- Most common connection media
- Four pairs of twisted wires to reduce interference
▪ Optical fibre cables
- Use light rays to transmit data
find more resources at oneclass.com
find more resources at oneclass.com
Wireless Connections
- Wireless network interface card (WNIC)
- Replaces an NIC to enable wireless connection
- Standard in most laptops
LAN Protocols
- World’s most popular protocol for LANs
- Ethernet or IEEE 802.3 protocol
- Supports 10/100/1000 Mbps Ethernet
- Protocol specifies:
- Hardware characteristics
- How messages are packaged and processed for transmission
Wireless LAN Protocols
- Wireless connections are becoming popular
- IEEE 802.11 protocol used in the home and within small offices to connect to LANs
- Bluetooth used over very short distances to replace wires, e.g. connecting a keyboard
- Connect to an access point (modem/router)
- Processes messages and communicates with the LAN switch
Q3: What Are the Alternatives for a WAN?
▪ WANs connect computers at separate sites
- Use routers and public communications links between sites
- Cable connections made through licensed public telecommunications companies
▪ Internet service provider (ISP)
- A company that provides customers with access to the internet
- Provides legitimate internet address
- Serves as a gateway to the internet
- Collects money from customers to pay for internet access
Connecting the Personal Computer to an ISP: Modems
- Computers are commonly connected to an ISP in one of three ways:
- DSL line (telephone line)
- Cable TV line
- Wireless
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Q1: what is a computer network: network. Communicate with one another over transmission line: three basic types of networks. Connected computers that reside in a single geographic location. Within a small distance of each other (approx. Connects between two and several hundred computers. Organisation controls the installation of the communications media. Uses communication networks from vendors that are licensed by government. Protocol is a set of rules that two devices must follow to communicate. Q2: what are the components of a lan: switch/router. Special purpose computer that receives and transmits messages: lan device. A switch, wireless communication device, and devices for connecting to a wan and via the wan to the internet: network interface card (nic) Hard(cid:449)are that (cid:272)onne(cid:272)ts ea(cid:272)h de(cid:448)i(cid:272)e"s (cid:272)ir(cid:272)uitry to the (cid:272)a(cid:271)le: utp (unshielded twisted pair) cable. Four pairs of twisted wires to reduce interference: optical fibre cables. Replaces an nic to enable wireless connection. How messages are packaged and processed for transmission.
