Cut through
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In computer networking, cut through is a type of network switch (or router) architecture for packet switching systems. Wherein the switch starts forwarding that frame (or packet) before the whole frame has been received, normally as soon as the destination address is processed. This technique reduces latency through the switch.
In packet switched networks such as Ethernet, cut-through switching can only be used where the outgoing interface is equal in speed to, or slower than the incoming interface.
Cut through routing in IP networks presents some problems since the IP checksum in the packet is supposed to be checked by every router in the path. Since the checksum of a packet cannot be checked until the entire packet has been received, the cut-through router is at risk of forwarding a packet with an incorrect checksum. Provided that there are other routers in the path which are not doing cut-through routing, or that the end system is correctly verifying checksums, this should only result in the occasional loss of a small amount of traffic capacity.
Cut through routing was one of the important features of ATM networks since the edge routers of the ATM network were able to use cell switching through the core of the network with low latency at all points. With higher speed links, this has become less of a problem since packet latency has become much smaller.