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Questions and Answers
What type of ISP provides internet services to a specific geographical area?
Which type of ISP provides internet services to a large geographical area, often spanning multiple cities or states?
What type of ISP provides internet services to a country or large region?
Which type of ISP provides internet services globally?
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What is the primary function of an ISP?
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What is an example of a type of network that an ISP might provide access to?
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What is the Internet often viewed as?
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What type of network is often used to provide internet access to a specific geographical area?
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What is the primary function of a national ISP?
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What type of ISP is often used to provide internet access to a large geographical area?
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Study Notes
Physical Layer Technologies
- Fiber optic cable has the highest transmission rate and lowest bit error rate in practice.
Jargon and Abbreviations
- Nuts and bolts: the basic practical details.
- HTTP: HyperText Transfer Protocol.
- Wi-Fi: actually IEEE 802.11, but a marketing firm suggested the name Wi-Fi which resembles Hi-Fi.
- There are many types of Wi-Fi: b, a, g, n, ac (wave 1,2), ax.
- TCP: Transmission Control Protocol.
- IP: Internet Protocol.
- ISP: Internet Service Provider.
- IETF: Internet Engineering Task Force.
- RFC: Request for Comments.
- IEEE: Institute of Electrical and Electronics Engineers.
- IoT: Internet of Things.
- DSL: Digital Subscriber Line.
- ADSL: Asymmetric DSL.
Access Networks
- Residential access networks.
- Institutional access networks (school, company).
- Mobile access networks (Wi-Fi, 4G/5G).
Digital Subscriber Line (DSL)
- Uses existing telephone line to central office DSLAM.
- Data over DSL phone line goes to the Internet.
- Voice over DSL phone line goes to the telephone network.
- 24-52 Mbps dedicated downstream transmission rate.
- 3.5-16 Mbps dedicated upstream transmission rate.
Home Networks
- Wireless and wired devices.
- Often combined in a single box.
- Cable or DSL modem.
- WiFi wireless access point (54, 450 Mbps).
- Wired Ethernet (1 Gbps).
- Router, firewall, NAT.
Wireless Access Networks
- Shared wireless access network connects end system to router.
- Via base station aka “access point”.
- Wireless local area networks (WLANs) typically within or around a building (~30 m).
- 802.11b/g/n (WiFi): 11, 54, 450 Mbps transmission rate.
- Wide-area cellular access networks provided by mobile, cellular network operator (10’s km).
- 10’s Mbps transmission rate.
Enterprise Networks
- Companies, universities, etc.
- Enterprise link to ISP (Internet).
- Institutional router.
- Ethernet switch.
- Institutional mail, web servers.
- IEEE: Institute of Electrical and Electronics Engineers.
- WiFi.
The Internet: A “Services” View
- Infrastructure that provides services to applications.
- Provides programming interface to distributed applications.
- “Hooks” allowing sending/receiving apps to “connect” to, use Internet transport service.
- Provides service options, analogous to the postal service.
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Description
A quiz on physical layer technologies in computer networks, comparing transmission rates and bit error rates of different technologies.
