Error Control In Data Link Layer Wiki
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citations to reliable sources. Unsourced material may be challenged and removed. (August 2008) (Learn how and when to remove flow and error control in data link layer this template message) In information theory and coding theory with
Error Control In Data Link Layer Ppt
applications in computer science and telecommunication, error detection and correction or error control are techniques that
Difference Between Error Control And Flow Control In Data Link Layer
enable reliable delivery of digital data over unreliable communication channels. Many communication channels are subject to channel noise, and thus errors may be introduced during
Data Link Layer Wikipedia
transmission from the source to a receiver. Error detection techniques allow detecting such errors, while error correction enables reconstruction of the original data in many cases. Contents 1 Definitions 2 History 3 Introduction 4 Implementation 5 Error detection schemes 5.1 Repetition codes 5.2 Parity bits 5.3 Checksums 5.4 Cyclic redundancy checks (CRCs) network layer wiki 5.5 Cryptographic hash functions 5.6 Error-correcting codes 6 Error correction 6.1 Automatic repeat request (ARQ) 6.2 Error-correcting code 6.3 Hybrid schemes 7 Applications 7.1 Internet 7.2 Deep-space telecommunications 7.3 Satellite broadcasting (DVB) 7.4 Data storage 7.5 Error-correcting memory 8 See also 9 References 10 Further reading 11 External links Definitions[edit] The general definitions of the terms are as follows: Error detection is the detection of errors caused by noise or other impairments during transmission from the transmitter to the receiver. Error correction is the detection of errors and reconstruction of the original, error-free data. History[edit] The modern development of error-correcting codes in 1947 is due to Richard W. Hamming.[1] A description of Hamming's code appeared in Claude Shannon's A Mathematical Theory of Communication[2] and was quickly generalized by Marcel J. E. Golay.[3] Introduction[edit] The general idea for achieving error detection and correction is to add some redundancy (i.e., some extra data) to a me
be challenged and removed. (January 2008) (Learn how and when to remove this template message) Structure of an Ethernet packet, including the FCS that terminates the physical layer wiki Ethernet frame.[1]:section 3.1.1 A frame check sequence (FCS) refers to the extra transport layer wiki error-detecting code added to a frame in a communications protocol. Frames are used to send upper-layer data data link layer functions and ultimately the application data from a source to a destination. The detection does not imply error recovery; for example, Ethernet specifies that a damaged frame should be discarded, https://en.wikipedia.org/wiki/Error_detection_and_correction but at the same time does not specify any action to cause the frame to be retransmitted. Other protocols, notably the Transmission Control Protocol (TCP), can notice the data loss and initiate error recovery.[2] Overview[edit] All frames and the bits, bytes, and fields contained within them, are susceptible to errors from a variety of sources. The FCS field https://en.wikipedia.org/wiki/Frame_check_sequence contains a number that is calculated by the source node based on the data in the frame. This number is added to the end of a frame that is sent. When the destination node receives the frame the FCS number is recalculated and compared with the FCS number included in the frame. If the two numbers are different, an error is assumed and the frame is discarded. The sending host computes a cyclic redundancy check on the entire frame and appends this as a trailer to the data. The receiving host recomputes the cyclic redundancy check on the frame using the same algorithm, and compares it to the received FCS. This way it can detect whether any data was lost or altered in transit. It may then discard the data, and request retransmission of the faulty frame. The FCS is often transmitted in such a way that the receiver can compute a running sum over the entire frame, together with the trailing FCS, expecting to see a fixed result (such as zero) whe
— Network Layer — Addressing — Routing Protocols — Data Link Layer — Switching — Physical Layer — Router Operation — Advanced Addressing Topics — Advanced Routing Topics — Advanced Switching Topics — Security — WAN — Configuration — Conclusion — References https://en.wikibooks.org/wiki/CCNA_Certification/Data_Link_Layer — About the Exam — Cisco Router Commands — Quick Reference Sheet Contents 1 Data Link Layer 1.1 Logical Link Control Sublayer 1.2 Media Access Control Sublayer 1.3 Examples 1.4 Interfaces 1.5 MAC 1.6 LLC 1.7 References 1.8 External links Data Link Layer[edit] The data link layer is layer two of the seven-layer OSI model as well as of the five-layer TCP/IP reference model. It responds to service requests from the network layer and data link issues service requests to the physical layer. This is the layer which transfers data between adjacent network nodes in a wide area network or between nodes on the same local area network segment. The data link layer provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the Physical layer. Examples of data link protocols are Ethernet for data link layer local area networks and PPP, HDLC and ADCCP for point-to-point connections. The data link is all about getting information from one place to a selection of other places. At this layer one does not need to be able to go everywhere, just able to go somewhere else. It is analogous to social interaction in that one needs to be able to talk to Bob to get a message to Fred or James. The data link provides data transfer across the physical link. That transfer might or might not be reliable; many data link protocols do not have acknowledgements of successful frame reception and acceptance, and some data link protocols might not even have any form of checksum to check for transmission errors. In those cases, higher-level protocols must provide flow control, error checking, and acknowledgements and retransmission. In some networks, such as IEEE 802 local area networks, the data link layer is split into MAC and LLC sublayers; this means that the IEEE 802.2 LLC protocol can be used with all of the IEEE 802 MAC layers, such as Ethernet, token ring, IEEE 802.11, etc., as well as with some non-802 MAC layers such as FDDI. Other data link layer protocols, such as HDLC, are specified to include both sublayers, although some other protocols, such as Cisco HDLC, use HDLC's low-level fr