länkskiktet

länkskiktet, eller länkriktet, is the Swedish term for the link layer, the second layer in the OSI reference model. It is responsible for node-to-node data transfer and the reliable delivery of frames across the physical medium. The key functions of länkskiktet include framing, addressing with MAC addresses, error detection, and flow control. In Ethernet, the frame format contains a preamble, destination and source MAC addresses and a payload. Wi‑Fi also operates at this layer, adding encapsulation for radio transmission and control of access via CSMA/CA. Point‑to‑point protocols such as PPP or DLCI defined in Frame Relay are other examples of link‑layer techniques.

länkskiktet provides an abstraction between the physical layer, which actually transmits bits, and the network layer above, which routes packets. The link layer can implement synchronization, burst‑mode data handling, and compare sent and received checksums to ensure data integrity. When multiple devices share a media, switching or bridging mechanisms operate at this layer, dynamically mapping MAC addresses to ports. In many modern networks, virtual LANs (VLANs) and jumbo frames are configured at länkskiktet to optimize traffic segregation and performance. The layer’s functions are defined in standards such as IEEE 802.3 for Ethernet and IEEE 802.11 for Wi‑Fi, and are implemented in hardware switches, routers, and network interface cards.