LAN switch types decide how a frame is handled when it’s received on a switch port. Latency– the time it takes for a frame to be sent out an exit port once the switch receives the frame– depends on the chosen switching mode. There are three switching modes: Cut-through (FastForward) When in this mode, the switch only waits for the destination hardware address to be received before it looks up the destination address in the MAC filter table. Cisco sometimes calls this the FastForward method. FragmentFree (modified cut-through) This is the default mode for the Catalyst 1900 switch, and it’s sometimes referred to as modified cut-through. In FragmentFree mode, the switch checks the first 64 bytes of a frame before forwarding it for fragmentation, thus guarding against forwarding runts, which are caused by collisions. Store-and-forward In this mode, the complete data frame is received on the switch’s buffer, a CRC is run, and, if the CRC passes, the switch looks up the destination addres
Cisco Certified Network Associate Exam,640-802 CCNA All Answers ~100/100. Daily update