How Layer 2 works and what it adds to the criteria

Layer 2 refers to the second layer of the OSI model, which is the Data Link Layer. It is responsible for transferring data between adjacent network nodes and ensuring reliable communication over a physical link.

In terms of how it works, layer 2 uses MAC (Media Access Control) addresses to identify devices on a local network. When a device wants to send data to another device on the same network, it encapsulates the data into frames and includes the MAC address of the destination device. The frame is then transmitted over the physical link.

Layer 2 also adds several important features to network communication. One of these features is error detection and correction. Layer 2 protocols, such as Ethernet, use techniques like CRC (Cyclic Redundancy Check) to detect errors in transmitted data and retransmit any corrupted frames.

Another important feature of layer 2 is flow control. This ensures that data is transmitted at an appropriate rate so that receiving devices can process it without being overwhelmed. Flow control mechanisms include techniques like buffering and sliding window protocols.
Layer 2 also provides addressing capabilities through MAC addresses. These addresses are unique identifiers assigned to each network interface card (NIC) and are used to deliver data directly to specific devices on a local network.

Additionally, layer 2 supports different types of topologies, such as bus, ring, and star configurations. Each topology has its own advantages and disadvantages in terms of scalability, fault tolerance, and performance.

In summary, layer 2 plays a crucial role in local network communication by providing error detection and correction, flow control, addressing capabilities through MAC addresses, and supporting various network topologies.