Communication Modes, Data Circuits, OSI Stack, and Network Types

Communication Modes

Operability:

• Simplex Communication: Clearly defined transmitter and receiver functions. Transmission occurs in one direction only. Example: a TV broadcast using a single physical channel and a single unidirectional logical channel.
• Half-Duplex Communication: Two-way communication where sender and receiver roles are interchangeable, but transmission is not simultaneous. When one device sends, the other must receive. It uses one physical channel and a bidirectional logical channel.
• Full-Duplex Communication: Bidirectional and simultaneous communication. Sender and receiver roles are not strictly defined.

Data Circuit Components

Circuit Data:

• Data Terminal Equipment (DTE): The source or destination of information.
• Data Circuit-Terminating Equipment (DCE): Adapts signals for the communications channel, converting them to a format suitable for the DTE.
• Data Line: Connects two DCEs.
• Data Link: The combination of DCEs and data lines.
• Data Circuit: The complete set of DCEs and transmission lines responsible for communication between the transmitting and receiving DTEs, ensuring information is delivered reliably.

The OSI Stack

The OSI Model Layers:

1. Physical Layer
2. Data Link Layer (Physical Address or MAC)
3. Network Layer (Logical Address, e.g., IP)
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer

Network Types: LAN, MAN, WAN

• Local Area Network (LAN): A network limited to a relatively small area, such as a room, building, ship, or airplane. Sometimes called a single-location network. Large LANs are often divided into smaller logical segments called Workgroups, which share common resources within the LAN.
• Metropolitan Area Network (MAN): A network connecting two or more LANs within a city or metropolitan area. Multiple routers, switches, and hubs are interconnected to create a MAN.
• Wide Area Network (WAN): A data communications network covering a broad geographic area, often using transmission facilities provided by common carriers (e.g., telephone companies). WAN technologies generally operate at the lower three layers of the OSI model: the Physical Layer, the Data Link Layer, and the Network Layer.