L1. Why do we need protocol layering? Flashcards
What is protocol layering?
The organization of network communication protocols into a hierarchical structure
What does a layer do?
Each layer is responsible for specific tasks related to data transmission
How do different layers interact?
Adjacent layers interact with eachother through standardized interfaces
What are the benefits of protocol layering?
Protocol layering allows for abstraction, modularization, and easier maintenance of networking systems
What does abstraction mean?
Abstraction involves hiding complex implementation details behind simpler interfaces
What does abstraction mean in the context of protocol layering?
Each layer in the protocol stack performs specific tasks without requiring any information about the implementation of protocols at other layers
What are the benefits of abstraction in the context of protocol layering?
Abstraction facilitates design, implementation, and troubleshooting of network protocols by allowing developers to focus on one layer at a time
Do changes to one network layer affect other layers?
Since each layer operates independently, changes or updates to one layer does not affect other layers so long as the interfaces between layers remain consistent
What model of the network stack have we looked at in this course?
The five-layer TCP/IP model
Name the layers of the protocol stack
Application Layer, Transport Layer, Network Layer, Link Layer, Physical Layer
What does the application layer do?
The application layer defines protocols and standards for application-level services
What are some application-level services?
Web browsing, email, file transfer, remote access
Name some application layer protocols and what they are used for
HTTP for web browsing, SMTP, IMAP, and POP3 for email, FTP for file transfer, DNS for resolving domain names to IP addresses
How do the application layer and transport layer communicate?
The application layer provides data to the transport layer, along with information on how the data should be transmitted, such as specifications for which transport protocol to be used. The transport layer takes outgoing data provided by the application layer and segments it, and makes sure incoming data is delivered to the correct process on the host
What does the transport layer do?
The transport layer is responsible for creating end-to-end connections between hosts
Name some transport layer protocols
The two main transport layer protocols are TCP and UDP. TCP is a connection-oriented protocol that ensures reliable, ordered delivery of data packets with mechanisms for error detection , retransmission, and flow control. UDP is connectionless and does not provide any of the reliability of TCP, but has lower latency. There is also the QUIC protocol which is based on UDP and offers similar low latency but has added features for reliability and security
What does the network layer do?
The network layer is responsible for addressing, routing, and forwarding data between networks. It determines the best path for data transmission accross interconnected networks.
Name some network layer protocols
The primary protocol used in the network layer is the Internet Protocol (IP), which includes version IPv4 and IPv6
What does the link layer do?
The link layer is responsible for the transmission of data between adjacent nodes in a network. It divides data into frames, adding headers and trailers for error detection and correction. It provides MAC addresses to network interfaces. It performs access control to avoid collisions in shared media networks. It detects and corrects errors that occur during transmission using techniques like CRC
Name some link layer protocols
Link layer protocols include Ethernet, for local area networks, and Wi-Fi for wireless local area networks
What does the physical layer do?
The physical layer is responsible for transmitting raw data bits over physical media, such as copper wire, fibre optics, or wireless transmission. It defines the electrical, optical, or radiosignalling characteristics used for the physical transmission of data
Name some physical layer protocols
The physical layer doesn’t have protocols as such, but it has standards and specifications. Link layer protocols Ethernet and Wi-Fi also encompass specifications used at the physical layer
