Computer Networks Flashcards
What is the significance of linking computers through communication?
Linking computers through communication has impacted the organization of modern computer systems;with operating systems and software now typically designed for exchanging data over a network.
What types of communication media can be used in computer networks?
Communication media can include copper lines;fiber optic cables;or radio links.
How has the use of isolated computer systems changed over the years?
Isolated computer systems have become rare;as most computers are now part of interconnected networks.
Why are today’s operating systems and software dependent on network communication?
They are designed to exchange data over a network;which is essential for their functionality.
What is discussed in the first part of the unit?
The first part focuses on the use of communication media and the basics of coding for data transmission.
What does the second part of the unit cover?
It discusses network topologies and how larger networks can be formed from individual communication networks.
What must be agreed upon before data transmission and communication can occur?
A comprehensive set of rules and conventions;known as protocols;must be established.
What is a protocol stack?
A protocol stack is a structured set of networking rules or protocols that governs communication.
Why are protocols important for computer communication?
Protocols ensure that communication proceeds in an organized and efficient manner.
How did people communicate before the digital age?
People communicated using direct speech;sounds;facial expressions;gestures;and long-distance methods like smoke signals;flags;mail correspondence;telegraphy;and analog telephones.
How do computers communicate today?
Computers communicate digitally…similar to how humans now communicate over long distances using digital technology.
Despite the trend toward digital communication;what is the nature of actual signal transmission?
Signal transmission is always analog;where digital values are mapped onto physical quantities such as current/voltage;light pulses;or electromagnetic waves.
What are common transmission media used for signal transmission?
Common transmission media include copper cables;fiber optic cables;and space for radio transmission.
What is required for transmitting a digital value like “0” or “1” over a medium?
The digital value must be mapped to a physical value of the transmission medium
Why is signal coding important in data transmission?
Signal coding ensures that valid mapping intervals are maintained despite signal distortion caused by attenuation or interference;and helps detect transmission errors.
What is line code in the context of data transmission?
Line code is the pattern used to map digital values to physical quantities for transmission and vice versa for reconstruction on the receiver side.
What is channel encoding and why is it used?
Channel encoding adds redundancy to detect and correct errors in transmission;tailoring the coding to the transmission channel’s characteristics.
When is source encoding used;and what is its effect on data transmission?
Source encoding is used to compress data before transmission;especially for data streams over low-capacity channels;like digital voice or multimedia streams. It reduces the data burden but may result in “lossy” content
What is modulation in the context of line encoding?
Modulation refers to the process of mapping digital symbols to physical quantities;such as using voltage levels for representing “0” and “1” in amplitude modulation.
What is the difference between baseband and passband transmission?
Baseband transmission uses frequencies from zero up to the signaling rate;while passband transmission shifts signals to a higher frequency range for transmission.
What is Manchester code and how does it work?
Manchester code uses phase modulation
How does a parity check help detect transmission errors?
A parity bit is appended to each block of data
How can parity blocks help correct transmission errors?
Parity blocks for columns of data allow the receiver to detect and locate specific bit errors;enabling correction by flipping the incorrect bit.
What are the three modes of communication in computer networks?
The three modes are simplex (one-way communication);half-duplex (alternating between sending and receiving);and full-duplex (simultaneous sending and receiving).
What is multiplexing and how does it work?
Multiplexing allows multiple data streams to share a communication channel by dividing it into time slices (time multiplexing) or using parallel channels;frequencies;or wavelengths.
How does frequency multiplexing differ from time multiplexing?
Frequency multiplexing uses different carrier frequencies for parallel transmission;while time multiplexing divides a single channel into time slots for multiple data streams.
Can multiplexing be combined with different operating modes like duplex or simplex?
Yes, multiplexing can be combined with simplex, half-duplex, or full-duplex modes for flexible handling of digital data streams.
Does the von Neumann architecture explicitly include communication with other computers?No;the von Neumann architecture does not explicitly include communication with other computers; however;communication can occur through the input/output component.
How is internal communication between the CPU and memory handled in a von Neumann computer?
Internal communication is handled using buses;specifically the address bus and the data bus;for communication between the CPU and main memory.
What is a bus topology in computer networks?A bus topology is a simple network design where multiple communication partners share a single medium;with only one partner sending data at a time while others receive it.
What are the challenges of using a bus topology for communication?
The main challenges are managing access to the shared medium and preventing collisions when multiple participants try to communicate simultaneously.
Why is the bus topology rarely used in modern networks?
It is less efficient than switched networks;which support duplex communication and multiplexing;allowing multiple pairs to communicate simultaneously.