History and Communication of the Internet

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Questions and Answers

What networking strategy did the original telephone network use?

Ring topology

Message switching

Circuit switching (correct)

Packet switching

Which of the following events marked a significant increase in the number of connected computers on the Internet?

The dismantling of the NSF backbone in 1994 (correct)

The split of ARPANET and MILNET in 1983

The creation of NSFNET as a backbone in 1985

NSFNET's move to 1.5 Mbps in 1986

What is the primary function of peering points in networking?

To transmit circuit-switched data

To connect different networks directly (correct)

To store and forward messages

To monitor network traffic

What was the maximum speed of NSFNET during its peak performance in the timeline provided?

45 Mbps Signup and view all the answers

Which technology allows for the storage and forwarding of messages in modern networking?

Packet switching Signup and view all the answers

Which type of address is designed to communicate with all nodes on a network?

Broadcast Signup and view all the answers

What process is responsible for deciding the best path a packet will take to reach its destination?

Routing Signup and view all the answers

In which multiplexing technique are packets from different sources interleaved on the link and scheduled per packet?

Statistical Multiplexing Signup and view all the answers

What is the term for the overflow that occurs when a buffer cannot accommodate incoming packets?

Congestion Signup and view all the answers

What does Inter-Process Communication help facilitate between applications?

Process-to-process communication Signup and view all the answers

Which abstraction is likely used in applications like video conferencing that handle sequences of data?

Stream-Based Signup and view all the answers

What is a key attribute of Frequency-Division Multiplexing (FDM)?

Sharing of bandwidth across channels Signup and view all the answers

What is the maximum data rate of a video stream with a resolution of 352 x 240 pixels at 24 bits per pixel, if it runs at 30 frames per second?

60Mbps Signup and view all the answers

What type of network error is caused by electrical interference?

Bit-level errors Signup and view all the answers

What are the building blocks of a network architecture that define message formats?

Protocols Signup and view all the answers

In which layer of the TCP/IP protocol suite does FTP operate?

Layer 5 Signup and view all the answers

Which interface facilitates communication with the peer in a protocol?

Peer-to-peer interface Signup and view all the answers

Which layer in the OSI model is responsible for data transfer between neighboring network elements?

Data link layer Signup and view all the answers

What type of packet error occurs when packets are delivered in a different order than they were sent?

Out-of-order packets Signup and view all the answers

Which of the following best describes the abstraction used in a layering architecture?

Simplifying the network process through encapsulation Signup and view all the answers

What is the main purpose of defining a service interface in a protocol?

To detail operations on the protocol Signup and view all the answers

What is the main implication of the hourglass design in Internet architecture?

It allows interoperability among different network technologies that support IP. Signup and view all the answers

Which of the following accurately defines latency in a network?

The total time taken from sending the first data bit to receiving the last data bit. Signup and view all the answers

How is transmit time calculated in a network?

Data Size / Bandwidth Signup and view all the answers

What does RTT stand for in networking contexts?

Round Trip Time Signup and view all the answers

What is the formula for calculating propagation delay?

Distance / Transmission Speed Signup and view all the answers

What is bandwidth generally defined as in networking?

The amount of data transmitted per time unit. Signup and view all the answers

Which of the following statements regarding packet-switched networks is true?

They require data to be divided into fixed-sized packets. Signup and view all the answers

Which metric combines the size of the data block with latency to evaluate network performance?

Throughput Signup and view all the answers

When sending multiple packets in a network, what happens during Round Trip Time (RTT)?

The sender must wait for a response after sending each packet. Signup and view all the answers

Which unit correctly describes 1 Mbps in decimal?

1,000,000 bits per second Signup and view all the answers

What is the correct formula for calculating latency?

Latency = Setup Time + Propagation + Transmit + Switch Processing Time Signup and view all the answers

How is throughput defined in the context of network performance?

Throughput = TransferSize / TransferTime Signup and view all the answers

What does the Delay x Bandwidth product represent?

The amount of data that can be sent before receiving an acknowledgment Signup and view all the answers

In which scenario does bandwidth dominate latency?

When transferring a 25MB message Signup and view all the answers

Which function is used to create a socket in the Socket API?

int socket(int domain, int type, int protocol) Signup and view all the answers

What action does the 'connect' function perform on the client side of a socket program?

It initiates a connection to the server Signup and view all the answers

What does 'accept' do in the context of socket programming on the server side?

It initiates a new socket connection for the client Signup and view all the answers

What is the main difference between Variable Bit Rate (VBR) and Constant Bit Rate (CBR)?

VBR adjusts based on network conditions while CBR is stable Signup and view all the answers

Which of the following is not a performance metric for networks?

Software complexity Signup and view all the answers

Study Notes

Brief History of the Internet

The Internet began as a research project in the 1970s.
Early networks were small with limited bandwidth and computing power.
By the 1980s, the internet grew with the development of ARPANET and MILNET.
The National Science Foundation (NSF) created NSFNET as a backbone for the Internet, linking supercomputer centers across the country.
The Internet expanded further in the 1990s, connecting regional networks and exceeding 100,000 computers.
The NSF backbone was dismantled in 1994 and replaced by multiple private backbones.
Today, the Internet connects over 600 million computers in over 190 countries with high-speed backbones.

Strategies for Network Communication

Circuit Switching: A dedicated path is established between two communication points, carrying bit streams.
Packet Switching: Data is broken down into packets, stored, and forwarded along various paths in the network.

Addressing, Routing, and Forwarding

Address: A byte string uniquely identifies a node in the network.
Unicast: Sends information to a specific node.
Broadcast: Sends information to all nodes in the network.
Multicast: Sends information to a subset of nodes in the network.
Routing: Determines the path each packet travels to reach its destination.
Forwarding: Transmits incoming packets to the correct output of a switch or router.

Multiplexing Techniques

Synchronous Time-Division Multiplexing (STDM): Time is divided into slots dedicated to transmitting data from different sources.
Frequency-Division Multiplexing (FDM): The frequency spectrum is divided into channels for different users, like TV channels.
Statistical Multiplexing: Packets from different sources are interleaved dynamically on the link based on demand.

Inter-Process Communication (IPC)

IPC enables host-to-host connectivity to become process-to-process communication, enabling common services.
IPC bridges the gap between what application programs expect and what the underlying network technology provides.

IPC Abstractions

Request/Reply: Used for distributed file systems, digital libraries (web), etc.
Stream-Based: Used for video applications like on-demand videos and video conferencing.

Network Errors

Bit-level errors: Caused by electrical interference.
Packet-level errors: Caused by network congestion.
Link and node failures: Can lead to packet delays, out-of-order packet delivery, or packet duplication.

Layering Architecture

Abstracts complex network functions.
Provides a structured hierarchy of layers.
Each layer can use different abstractions and protocols to communicate with other layers.

Protocols

Define the format, order, and actions of messages between network entities during transmission and receipt.
Protocol objects have a service interface for operations within the protocol and a peer-to-peer interface for communication with other protocols.

TCP/IP Protocol Suite

Application Layer: Provides functionalities for supporting network applications (like FTP, SMTP, HTTP).
Transport Layer: Manages process-to-process data transfer (like TCP and UDP).
Internet Layer: Enables host-to-host data transfer (like IP and Routing protocols).
Data Link Layer: Facilitates data transfer between neighboring network elements (like PPP and Ethernet).
Physical Layer: Transmits raw bits on the physical media.

ISO/OSI Model vs. TCP/IP Model:

Both models are layered architectures for network communication with different approaches.
The ISO/OSI model is more comprehensive, while the TCP/IP model is widely adopted in practice.

Internet Architecture

Defined by the Internet Engineering Task Force (IETF).
Follows the Hourglass Design: A common Internet Layer (IP) connects a wide range of applications and network technologies.
Applications like FTP, HTTP, NV, and TFTP utilize the Transport layer (TCP/UDP) built on top of the Internet Layer (IP).

Implications of Hourglass Model

IP enables interoperability between diverse networks.
Applications can run seamlessly on various network technologies.
Development efforts can proceed independently for applications and network technologies.

Network Performance

Latency: The time it takes for a data block transmission.
Throughput: The amount of data transferred per unit of time.
Effective Bandwidth: The actual data rate achieved, considering factors like packet size and latency.
Latency depends on:
- Setup time
- Transmit time
- Propagation delay
- Queuing delay

Performance Metrics

Transmit time: The time taken to send a data block over a link.
Propagation delay: The time for a signal to travel across a link.

Packet-Switched Networks

Data is broken down into packets and sent individually over the network.
Latency includes the time for all packets to be transmitted and received.
Round-Trip Time (RTT) is the time it takes for a packet to be sent and an acknowledgement to be received.

Delay x Bandwidth Product:

Represents the amount of data "in flight" within the network.
Usually measured relative to RTT.

Bandwidth vs. Latency

Latency dominates for small data packets (e.g., 1 byte message).
Bandwidth dominates throughput for large data packets (e.g., 25 MB message).

Other Network Performance Metrics

Application’s Bandwidth Need: VBR (variable bit rate) vs. CBR (constant bit rate).
Delay Jitter: Variation in packet arrival times.
Reliability: Packet loss rate.
Efficiency: Overhead of implementation.

Implementing Network Software (Socket API)

socket(): Creates a socket object for communication.
connect(): Establishes a connection to a remote host.
bind(): Assigns an address to a socket.
listen(): Starts listening for incoming connections.
accept(): Accepts an incoming connection.
send(): Sends data over the socket.
recv(): Receives data over the socket.

Example Socket Programs

Client-side Program: Creates a socket, connects to the server, sends data, and closes the connection.
Server-side Program: Creates a socket, binds to an address, listens for connections, accepts connections, receives data, and closes the connection.

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Description

Explore the evolution of the Internet from its inception in the 1970s to its vast global presence today. This quiz covers the fundamental strategies for network communication, including circuit and packet switching, as well as addressing and routing principles. Test your knowledge on how these components shape modern connectivity.