A computer network is a set of computers sharing resources located on or provided by network nodes. -Wikipedia
To put it simply, computer networking is the transporting and exchanging data between nodes (devices or computers). Nodes transmit data across a network via LANS (Local Area Networks) or WANS (Wide Area Networks) through various mediums. With regards to the Internet, nodes transmit data using an IP (Internet Protocol) address. Don't worry too much about the jargon for now, I'll explain them in their respective sections.
Types of Network
6 Types of Networks Used Today
1. Personal Area Network (PAN)
A PAN connects a user's device to other electronic device within a specified range. The most common example of a PAN is a Bluetooth connection.
2. Local Area Network (LAN)
A LAN is one of the most common and simplest types of networks. It's purpose is to connect devices within a building or a few buildings to share information. This can either be done through physical connections. The usage of routers or modems can connect a LAN to the internet.
3. Wireless Local Area Network (WLAN)
WLAN is similar to LAN, however, the difference is that as the name implies uses wireless technologies such as Wi-Fi.
4. Metropolitan Area Network (MAN)
MANs are typically larger than LANs but smaller than WANs. Its primary purpose is to connect devices that span an entire geographic region such as a town or city.
5. Wide Area Network (WAN)
A WAN connects devices across longer physical distances. The most common example of WAN is the internet.
6. Virtual Private Network (VPN)
A VPN extends a private network across the internet to send or recieve data securely by creating an encrypted tunnel.
Overview of the TCP/IP Network
The TCP/IP network model was created to reduce complexity and to standardize a foundation for companies to build their networks upon. It was in the 1970s that the OSI and TCP/IP model were developed, which led to vendor neutrality. Around the 1990s, the TCP/IP model became the primary choice due to its simplicity.
The TCP/IP model consists of 5 layers (categories): application layer, transport layer, network layer, data-link layer, and the physical layer. Each layer consisted of it's own set of rules (protocols) that define how said layer functions.
Application Layer The application layer focuses on specific services it needs to operate, basically it provides a way for users to interact with the network. For example, HTTP is one of the most common application layer protocol. It defines how web browsers can retrieve data from a server.
Transport Layer The transport layer basically provide services to the application layer in order to guarantee the deliver of data across a network. Since the main purpose of the transport layer is to communicate with the layers above or below itself; it is important to understand the following terms: "same-layer interaction" and "adjacent-layer interaction."
Same-layer interaction is when a layer from one device with the same layer on another device. For example, layer 4 on device A interacting with layer 4 on device B. Adjacent-layer interaction simply means that a layer in a single device is communication with the layers above or below itself.
Network Layer The network layer enables devices and networks to be interconnected. It does this by "routing" data across the network.
Data-Link and Physical Layers The data-link and physical layers work so closely together that some standards define them together. The main function of the data-link layer is to focus on the service it provides to the layers above it and the physical layer focuses mainly on the cabling and electrical signals.
How do these layers communicate?
The way each layer sends data to each other is by "encapsulating" data in headers and trailers.
Step One: Application Layer Encapsulates the data in the application layer in a header.
Step Two: Transport Layer Encapsulates data received from the application layer in another header.
Step Three: Network Layer Encapsulates data received from the transport layer in another header.
Step Four: Data-Link Layer Encapsulate data received from the network layer in a header and a trailer. Note: The data-link layer is the only layer that encapsulates the data inside a trailer.
Step Five: Physical Layer Sends the data.
Each time the data is encapsulated the given data is provided a name.
