Podcast
Questions and Answers
What term is used to describe the devices that run network applications at the Internet's edge?
What term is used to describe the devices that run network applications at the Internet's edge?
Which of the following is NOT a type of communication link mentioned in the overview?
Which of the following is NOT a type of communication link mentioned in the overview?
What primary role do packet switches play in the Internet?
What primary role do packet switches play in the Internet?
Which term is most associated with the concept of performance related to data transmission?
Which term is most associated with the concept of performance related to data transmission?
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What do the terms 'packet switching' and 'circuit switching' refer to?
What do the terms 'packet switching' and 'circuit switching' refer to?
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What is the primary function of an Internet service provider (ISP)?
What is the primary function of an Internet service provider (ISP)?
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Which of the following statements about network architecture is accurate?
Which of the following statements about network architecture is accurate?
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Which device is specifically designed to remote control cable TV via the Internet?
Which device is specifically designed to remote control cable TV via the Internet?
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What aspect of the Internet is concerned with security, performance, and protocols?
What aspect of the Internet is concerned with security, performance, and protocols?
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Which of the following devices is an example of a fun Internet-connected device?
Which of the following devices is an example of a fun Internet-connected device?
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What is the primary function of a host in a data transmission network?
What is the primary function of a host in a data transmission network?
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Which type of wired connection can achieve speeds of 10 Gbps?
Which type of wired connection can achieve speeds of 10 Gbps?
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What describes unguided media?
What describes unguided media?
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What is the maximum channel capacity of terrestrial microwave links?
What is the maximum channel capacity of terrestrial microwave links?
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Which of the following is true about fiber optic cables?
Which of the following is true about fiber optic cables?
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How is data transmitted through Ethernet?
How is data transmitted through Ethernet?
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What is the role of repeaters in fiber optic transmission?
What is the role of repeaters in fiber optic transmission?
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What is the main limitation of wireless radio connections?
What is the main limitation of wireless radio connections?
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What describes the concept of transmission delay?
What describes the concept of transmission delay?
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How long will it take for the first car to arrive at the second toll booth if each toll booth takes one minute to service a car?
How long will it take for the first car to arrive at the second toll booth if each toll booth takes one minute to service a car?
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What happens when the traffic intensity, defined as $La/R$, exceeds 1?
What happens when the traffic intensity, defined as $La/R$, exceeds 1?
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What does the 'traceroute' program measure?
What does the 'traceroute' program measure?
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What is the average queueing delay when the traffic intensity $La/R$ approaches 0?
What is the average queueing delay when the traffic intensity $La/R$ approaches 0?
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At what speed do cars propagate in the analogy given?
At what speed do cars propagate in the analogy given?
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What is a common feature of Internet protocols?
What is a common feature of Internet protocols?
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Which of the following is an example of a service provided by the Internet?
Which of the following is an example of a service provided by the Internet?
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What is the primary purpose of an Internet protocol like HTTP?
What is the primary purpose of an Internet protocol like HTTP?
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Which component is responsible for connecting users to the wider Internet?
Which component is responsible for connecting users to the wider Internet?
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What does RFC stand for in the context of Internet standards?
What does RFC stand for in the context of Internet standards?
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What role does the Internet Engineering Task Force (IETF) play?
What role does the Internet Engineering Task Force (IETF) play?
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Which of the following is NOT typically a characteristic of the Internet as a service?
Which of the following is NOT typically a characteristic of the Internet as a service?
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Which one of the following is a key characteristic of 4G mobile networks?
Which one of the following is a key characteristic of 4G mobile networks?
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What does the term 'hook' refer to in the context of Internet services?
What does the term 'hook' refer to in the context of Internet services?
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What is a major advantage of interconnected ISPs in the Internet infrastructure?
What is a major advantage of interconnected ISPs in the Internet infrastructure?
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What is the primary characteristic of the Internet structure described as a 'network of networks'?
What is the primary characteristic of the Internet structure described as a 'network of networks'?
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What implication does the presence of multiple ISPs have on Internet functionality?
What implication does the presence of multiple ISPs have on Internet functionality?
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How does competition among ISPs affect consumer choice?
How does competition among ISPs affect consumer choice?
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Which statement best describes the interaction among ISPs in the context of performance?
Which statement best describes the interaction among ISPs in the context of performance?
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What potential challenge arises from having multiple ISPs in the network structure of the Internet?
What potential challenge arises from having multiple ISPs in the network structure of the Internet?
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What is the primary technology used in hybrid fiber coax (HFC) networks?
What is the primary technology used in hybrid fiber coax (HFC) networks?
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What typical transmission rate range can be expected for DSL access networks?
What typical transmission rate range can be expected for DSL access networks?
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What characteristic defines shared wireless access networks?
What characteristic defines shared wireless access networks?
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Which of the following is the maximum transmission rate for WiFi under the 802.11n standard?
Which of the following is the maximum transmission rate for WiFi under the 802.11n standard?
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What is frequency division multiplexing (FDM) used for in cable-based access networks?
What is frequency division multiplexing (FDM) used for in cable-based access networks?
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What type of access network typically utilizes microwave transmission technologies?
What type of access network typically utilizes microwave transmission technologies?
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What device separates voice and data signals in a DSL access network?
What device separates voice and data signals in a DSL access network?
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What is a significant feature of enterprise networks compared to residential networks?
What is a significant feature of enterprise networks compared to residential networks?
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Which is a common characteristic of mobile access networks?
Which is a common characteristic of mobile access networks?
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What is the main function of a cable modem in a cable-based access network?
What is the main function of a cable modem in a cable-based access network?
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What type of device is typically used to manage traffic in enterprise networks?
What type of device is typically used to manage traffic in enterprise networks?
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What type of access network is most commonly found in schools and companies?
What type of access network is most commonly found in schools and companies?
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In which type of wireless access network is the range typically limited to a short distance, such as within a building?
In which type of wireless access network is the range typically limited to a short distance, such as within a building?
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What is the role of a cable headend in a cable-based access network?
What is the role of a cable headend in a cable-based access network?
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Study Notes
Computer Networks and Network Programming in Java
- Lectures by Dr. inż. Kazimierz Zieliński
- Email: [email protected]
Chapter 1: Introduction
- Goal: Get a feel for the "big picture" of computer networking, introducing terminology, with more depth explored later.
- Approach: Use the Internet as an example.
-
Roadmap:
- What is the Internet?
- What is a protocol?
- Network edge: hosts, access networks, physical media
- Network core: packet/circuit switching, Internet structure
- Performance: loss, delay, throughput
- Security
- Protocol layers, service models
- History
The Internet: "Nuts and Bolts" View
- Billions of connected computing devices (hosts) running network applications at the Internet's edge.
- Packet switches (routers, switches) forward packets (chunks of data).
- Communication links (fiber, copper, radio, satellite) with transmission rate (bandwidth).
- Collection of devices, routers, and links managed by an organization.
"Fun" Internet-Connected Devices
- Examples: Amazon Echo, Internet refrigerator, security camera, Internet phones, IP picture frame, Slingbox (remote cable TV control), Pacemaker & Monitor, Tweet-a-watt (energy monitor), Web-enabled toaster, AR devices, Fitbit, and others.
The Internet: "Network of Networks"
- Interconnected Internet Service Providers (ISPs).
- Protocols are everywhere, controlling sending/receiving of messages. Examples include HTTP (Web), streaming video, Skype, TCP/IP, WiFi, 4G, and Ethernet.
- Internet standards: RFCs (Request for Comments) and IETF (Internet Engineering Task Force).
The Internet: "Service" View
- Infrastructure that provides services to applications (web, streaming video, teleconferencing, email, games, e-commerce, social media, and interconnected appliances).
- Provides a programming interface to distributed applications with "hooks" allowing sending/receiving of applications to connect to and use Internet transport services.
- Similar in function to postal service, providing service to applications.
What's a Protocol?
- Human protocols (e.g., "what's the time?", "I have a question").
- Network protocols govern communication activity in the Internet.
- Protocols define the format, order of messages, and actions taken during message transmission and receipt.
Chapter 1: Roadmap
- What is the Internet?
- What is a protocol?
- Network edge: hosts, access network, physical media
- Network core: packet/circuit switching, Internet structure
- Performance: loss, delay, throughput
- Security
- Protocol layers, service models
- History
A Closer Look at Internet Structure
- Network edge: Hosts (clients and servers), servers often in data centers.
- Access networks, physical media: Wired and wireless communication links.
- Network core: Interconnected routers, network of networks.
Internet Topology Map
- Source is the Center for Applied Internet Data Analysis (CAIDA).
Access Networks and Physical Media
- How to connect end systems to edge routers: - residential, institutional, mobile networks (WiFi, 4G/5G).
- Specific properties to look for: transmission rate (bits per second), shared or dedicated access among users.
- Examples:
- Cable-based access (frequency division multiplexing (FDM))
- Digital Subscriber Line (DSL)
- Home networks (WiFi, wired Ethernet)
- Wireless access networks (WLANs, cellular networks)
- Enterprise networks (Ethernet, WiFi)
Links: Physical Media
- Bit: Propagates between transmitter/receiver pairs.
- Physical link: Connects transmitter and receiver.
- Guided media: Signals propagate in solid media (copper, fiber, coax).
- Unguided media: Signals propagate freely (radio). Specific example types include twisted pair (TP), coaxial cable, fiber optic cable, wireless radio.
Packet Switching: Store-and-Forward
- Hosts break application messages into packets.
- Packets are forwarded from one router to the next across links.
- Each packet is transmitted at full link capacity.
Packet Switching: Queueing Delay, Loss
- Packets queue in router buffers.
- If arrival rate exceeds link transmission rate, packets queue and can be dropped if memory fills up.
Two Key Network-Core Functions
- Forwarding: Local action; move arriving packets from router input links to appropriate output links.
- Routing: Global action; determine source-destination paths.
Alternative to Packet Switching: Circuit Switching
- End-end resources are allocated and reserved for a call between source and destination, similar to dedicated circuits.
Circuit Switching: FDM and TDM
- FDM (Frequency Division Multiplexing): Calls allocated their own frequency band.
- TDM (Time Division Multiplexing): Calls allocated time slots to transmit.
Packet Switching Versus Circuit Switching
- Packet switching allows more users to share a network.
- Circuit switching dedicates resources to single calls.
Internet Structure: A "Network of Networks"
- Hosts connect to the Internet via access ISPs.
- Access ISPs are interconnected.
- ISPs have economic agreements.
Chapter 1: Roadmap
- What is the Internet?
- What is a protocol?
- Network edge: hosts, access network, physical media
- Network core: packet/circuit switching, Internet structure
- Performance: loss, delay, throughput
- Security
- Protocol layers, service models
- History
Performance: Loss, Delay, Throughput
- Loss: Packets can be dropped due to buffer overflow.
- Delay: Transmission, propagation, queuing delays.
- Throughput: Rate at which bits can be sent from sender to receiver.
Security
- Field of network security includes understanding how bad guys can attack networks, how to defend against attacks, and how to build secure network architecture.
Protocol Layers, Service Models
- Networking is a complex system requiring an organizational model for discussion.
- Layered reference models define services via layer-to-layer interactions.
Internet Protocol Stack
- application: Supporting network applications (IMAP, SMTP, HTTP)
- transport: Process-process data transfer (TCP, UDP)
- network: Routing datagrams (IP)
- link: Data transfer between neighboring network elements (Ethernet, 802.11, PPP)
- physical: Bits/on the wire
Additional Chapter 1 Slides
- ISO/OSI reference model; comparison with Internet protocol stack's application, transport, network, link, and physical layers.
- Wireshark (packet analyzer).
Internet History
- Timeline of early packet-switching principles (1961-1972)
- Timeline of internetworking, new and proprietary network development (1972-1980)
- Timeline of new protocols, and proliferation of networks, (1980-1990)
- Timeline of commercialization, the Web, new applications (1990-2000s)
- Timeline showing further development and expanding use of the Internet (2005-present)
Chapter 1 Summary
- Broad overview of internet history and key aspects.
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