A layer two network is one that has a single administration Router and then the entire rest of the structure is made up of equipment such as a switch, CPE in a bridge and thus reaches the end client. With this structure you generate a very low level of security and the broadcast traffic that would be generated.

Saying that a network is at “layer 2” means that it operates at the data link layer of the OSI (Open Systems Interconnection) model. This model is a conceptual reference that divides the functions of a telecommunications network into seven abstract layers to assist in the design and implementation of interconnected communication systems.

The data link layer is the second layer of this model.

Main Functions of Layer 2:

• Framing: The data link layer is responsible for converting the raw bit stream from the physical layer (layer 1) into data units called frames. These frames contain hardware addresses (such as MAC addresses on Ethernet networks), which allow data to be directed to the correct device within a local network.
• Media Access Control (MAC): This layer defines how devices on the same physical network access the transmission media and communicate with each other. This includes protocols that avoid collisions and manage access to the shared medium, such as CSMA/CD on Ethernet or CSMA/CA on Wi-Fi.
• Detection and, optionally, correction of errors: The data link layer can detect errors in received data by using redundancy checks, such as CRC (Cyclic Redundancy Check). Some Layer 2 protocols can also correct these errors without the need for retransmission.
• Flow control: Prevents the sender from overloading the receiver with too much data at once.

Examples of Layer 2 Technologies:

• Ethernet: It is the most commonly used Layer 2 technology in local area networks (LAN).
• PPP (Point-to-Point Protocol): Used on direct connections between two nodes.
• Frame Relay and ATM (Asynchronous Transfer Mode): Previously popular Layer 2 technologies for wide area networks (WAN).

Importance of Layer 2:

The data link layer is crucial for establishing and maintaining reliable communication over a physical network. Operating at Layer 2, networks can employ switches and bridges to segment traffic, improve performance by isolating collision domains, and increase security by implementing VLANs (Virtual LANs) and access control protocols. network.

In summary, when a network is said to be at “layer 2,” it means that it uses protocols and technologies that operate at the data link layer of the OSI model, which is essential for the effective delivery of data in a network. local network.