Lecture 1 Flashcards
Covers lecture one
What is a communication network?
A set of equipment (hardware & software) and facilities that provide basic communication service
Enables the exchange of information between users at different locations.
What are the main types of communication networks?
- Telegraph Networks
- Telephone Networks
- Internet
- Next-Generation Internet
Each type uses different technologies for data transmission.
What is Circuit Switching?
A method that establishes a dedicated communication path between two stations
It consists of three phases: Establish, Transfer, Disconnect.
What defines Packet Switching?
Data is transmitted in packets, and different paths can be used to get packets to their destination
Packets are received, stored, and forwarded.
What is the difference between Circuit Switching and Packet Switching?
- Circuit Switching: Inefficient, used for entire call duration, easy routing
- Packet Switching: Efficient, used on demand, difficult routing
Circuit Switching is suited for voice traffic, while Packet Switching is suited for data traffic.
What is a protocol?
A set of rules that governs how communicating entities in a layer interact
It includes messages sent and actions taken during certain events.
What are the layers in a layered architecture?
- Application Layer
- Transport Layer
- Network Layer
Each layer provides services to the layer above.
What is the purpose of layering in network architecture?
To simplify design, implementation, and testing by partitioning the overall communications process
It allows for separate protocol design and flexibility in modifying protocols.
What is HTTP?
An application layer protocol that retrieves documents on behalf of a browser application
It specifies fields in request and response messages.
What does TCP stand for and what is its function?
Transmission Control Protocol; provides reliable byte stream service between processes
TCP is connection-oriented.
What is the DNS protocol?
An application layer protocol that allows queries of different types, such as name-to-address
It uses short messages and typically relies on UDP.
What is UDP?
User Datagram Protocol; provides best-effort datagram service between processes
UDP is connectionless and quick but not reliable.
What is the OSI Reference Model?
A seven-layer abstract reference model for network architecture
It provides a framework for the development of protocols and a unified view of layers.
What does the Physical Layer do?
Transfers bits across a link and defines the physical aspects of a communication link
Includes mechanical, electrical/optical, and functional specifications.
What is the function of the Data Link Layer?
Transfers frames across direct connections and detects bit errors
It also manages medium access control and flow control.
What is the role of the Network Layer?
Transfers packets across multiple links and networks, involving routing and addressing
It includes congestion control and connection management.
What services do the Application Layer provide?
- DNS
- Web access
- File transfer
It offers services frequently required by applications.
What is encapsulation in networking?
The process of wrapping data with protocol information at each layer
Each protocol uses headers that contain addresses and control information.
What are Protocol Data Units (PDUs)?
Units of data exchanged between peer processes in the OSI model
They are used for communication between layers.
What is the difference between connection-oriented and connectionless services?
- Connection-Oriented: Requires connection setup, e.g., TCP
- Connectionless: No connection setup, e.g., UDP
Connection-oriented services are more reliable but slower.
