L2lähetysyksikkö

L2lähetysyksikkö is a Finnish term that translates to "L2 transmission unit" or "L2 sending unit" in English. This term is primarily used in the context of telecommunications and network engineering, specifically within the data link layer (Layer 2) of the OSI model. It refers to a component or functional block responsible for encapsulating and transmitting data frames across a network link.

The core function of an L2lähetysyksikkö is to take data packets from higher network layers, typically the network layer (Layer 3), and prepare them for transmission over a physical medium. This involves adding a Layer 2 header and trailer, which contain control information such as source and destination MAC addresses, error detection codes (like CRC), and frame delimiters. Once encapsulated, the L2lähetysyksikkö then passes the complete data frame to the physical layer for actual transmission.

In different network technologies, the specific implementation and name of the L2lähetysyksikkö may vary. For example, in Ethernet networks, it would be part of the Ethernet interface card or controller. In other protocols like Wi-Fi or PPP, the functionality is integrated into the respective network adapters and drivers. The concept emphasizes the modularity of network protocols, where specific layers handle distinct tasks, and the L2lähetysyksikkö is a crucial part of the Layer 2 data flow. It ensures that data is correctly formatted and sent out onto the network medium according to the rules of the Layer 2 protocol in use.