Data Link Layer: Protocols, Error Control, and Flow Control
Data Link Layer
Liaison Service Layers
Ensures the integrity of packets received from the physical layer, controlling errors, and managing flow control.
Background
Divides the sequence of bits into transmission frames. A computing algorithm checks these frames to avoid bandwidth waste and facilitate error checking, allowing for less competition in the physical environment.
Framing Methods
- Character Count: An additional character indicates the number of characters in the frame.
- Character Stuffing: Flags
Understanding HTTP: A Comprehensive Guide
What is HTTP?
HTTP, or Hypertext Transfer Protocol, is the foundation of data exchange on the World Wide Web (WWW). It’s the most common method for exchanging information online, as described in RFC 1945. The secure version, HTTPS, utilizes various encryption methods.
A Brief History of HTTP and the WWW
In 1990, the World Wide Web (WWW), or simply the Web, was developed. This system, based on hypertext, revolutionized information sharing. Initially a simple multimedia navigation system, the Web
Read MoreSystem Design: Logical and Physical Design in Software Development
System Design: Logical and Physical
Physical Design
Physical design is the implementation of the system’s tasks, combining components and functions.
Key Features:
- Hardware Design: Specifying all computer equipment, including input, processing, and output devices, along with their performance characteristics.
- Software Design: Specifying all software features. For example, if the logical design requires users to update the database, the physical design specifies the system that enables this.
- Database Design:
Understanding PCI Bus Architecture and Peripheral Devices
PCI BUS
1 Structure
The PCI bus supports a variety of configurations with one or more processors and 49 mandatory signal lines (# indicates active low signal):
- System: Reset clock (CLK and RST#)
- Addresses and data: 32 lines for multiplexed address and data (little endian) -> AD[31:0], plus 4 multiplexed control lines -> C/BE#[3:0] (Command/Byte Enable), and a parity control line (PAR)
- Control Interface: Timing and coordination of transfers (6 lines): indication and duration of the beginning of
Data Link Layer: Packets, Access Methods, and Topologies
Data Link Layer: A Comprehensive Overview
Preparing Data Link Layer Packets
Packets are prepared for transmission by encapsulating them with a header and a trailer, creating a frame for transport across the local media.
Methods of Access to the Data Link Layer
Four general methods provide access to the data link layer:
Shared Media Access Control
- Controlled Access: Each node has its own time to use the medium (e.g., ring topology).
- Contention-Based Access: All nodes compete for medium usage (e.g., bus
Operating System Structures, Services, and Processes
OS Structures
Monolithic
The first OS structure, built as a single program with subroutines linked together, allowing each routine to call any other.
Features:
- Construction based on separately compiled modules joined by a linker.
- No protections or privileges.
- Fast and efficient execution and management.
Hierarchical
Divides the OS into autonomous parts with well-defined interfaces.
Features:
- Processor planning.
- Memory management (monolithic, caching, etc.).
- Console/operator control.
- Input/output management.
- File/