Data-Link Layer The data-link layer, Layer 2, defines standards that assign meaning to the bits carried by the physical layer. It establishes a reliable protocol through the physical layer so the network layer (Layer 3) can transmit its data. The data-link layer typically includes error detection and correction to ensure a reliable data stream. The data elements carried by the data-link layer are called frames. Examples of frame types include X.25 and 802.x (802.x includes both Ethernet and Token Ring networks). The data-link layer is usually subdivided into two sublayers, called the logical link control (LLC) and media access control (MAC) sublayers. If used, the LLC sublayer performs tasks such as call setup and termination (the OSI model can be applied to telecommunications networks as well as LANs) and data transfer. The MAC sublayer handles frame assembly and disassembly, error detection and correction, and addressing. The two most common MAC protocols are 802.3 Ethernet and 802.5 Token Ring. Other MAC protocols include 802.12 100Base-VBG, 802.11 Wireless, and 802.7 Broadband.
Posted on: Sun, 21 Sep 2014 04:23:30 +0000
Trending Topics
Recently Viewed Topics
© 2015