To pass the CCNA exam and earn this important certification, youve got to know switching inside and out. While youre learning all the basic switching theory, make sure to spend some time with the one of three switching modes Cisco routers can use.
Store-and-Forward is exactly what it sounds like. The entire frame will be stored before it is forwarded. This mode allows for the greatest amount of error checking, since a CRC (Cyclical Redundancy Check) is run against the frame before it is forwarded. If the frame contains an error, it is discarded. If theres no problem with the frame, the frame is then forwarded to its proper destination.
While store-and-forward does perform error checking, the delay in processing the frame while this error check is run results in higher latency than the other modes youre about to read about. The latency time can also vary, since not all frames are the same size.
Cut-through switching copies only the destination MAC address into its memory before beginning to forward the frame. Since the frame is being forwarded as soon as the destination MAC is read, there is less latency than store-and-forward. The drawback is that...