ccna 200 301 syllabus definition wikipedia francais

ccna 200 301 syllabus definition wikipedia francais.(1) Store-and-forwardIn store-and-forward switching, when the switch receives data, the switch stores the data in a buffer until the complete frame has been received. In the storeforwarding process, the switch performs CRC (CyclicRedundancyCheck) in addition to analyzing the destination address of the data frame Frames that fail the CRC check are discarded by the switch.(2) Cut-throughIn Cut-through switching, the switch starts processing the data as soon as it receives it, and does not need to wait until the entire data frame is received. The switch caches the destination MAC address of the data frame so that it can determine from which port or ports to forward the data. Chapter 3 describes the Ethernet frame format, and you know that the leading bits of a data frame have 8 bytes, followed closely by the 6-byte destination MAC address of the data frame. When the switch receives the destination MAC address of a data frame, it looks up the destination MAC address and the corresponding port in the MAC address table, and then forwards the data frame out the corresponding port. In Cut-through switching, the switch does not perform any error checking. Because the switch does not have to wait for the entire frame to be fully cached before it starts forwarding, Cut-through switching is faster than store-and-forward. However, because the switch does not perform any error checking, some erroneous data frames are transmitted across the network and are not discarded until they reach the final device. Cut-through switching transmits some data frames with errors and wastes the bandwidth of the network.279 AThere are two types of Cut-through switching.. Fast-forward: Fast-forwarding is the forwarding of 14 bytes of a data frame as soon as it is received. Fast-forward is the typical Cut.through switching method.. Fragment^free: In fragment-free forwarding, the switch receives 64 bytes of a data frame and starts forwarding the frame. Fragment-free forwarding can be seen as a compromise between store-and-forward and cut.through. As to why 64 bytes was chosen, it is because most network errors and collision processes occur in the first 64 bytes, i.e., most erroneous data frames are less than 64 bytes.El Note: Because Fast. forward is typically Cut-through, many documents divide the switch forwarding method as: Store-and-ForwardCut-through^ Fragment-freeo