hi srini
Throughput is a data communications term referring to the actual level of traffic put through the network across a path between a transmitting device and one or more receiving devices, from end to end. (In other words, throughput is a measurement of what real data went in one end and came out the other.)
The network path may involve multiple links and channels and multiple intermediate devices, such as switches and routers. Throughput can never be greater than bandwidth, and generally is quite a bit less for a number of reasons, which I'll list in no particular order.
First, packets errored in transmission may require retransmissions, assuming that the error control mechanism employed is that of recognition and retransmission. Retransmissions eat up some bandwidth.
Second, packet data protocols all involve some level of overhead in the form of various packet headers and trailers, which are signaling and controlling data rather than user payload.
Third, various data communications protocols involve some level of additional overhead for things like call setup, acknowledgments of packet receipt, negative acknowledgements errored packets received, call teardown, and various other control messages.
Fourth, congestion in packet networks may cause packets to be discarded when the buffers in devices (e.g., switches and routers) overflow. Commonly, those packets require retransmissions, which are requested when the receiving device realizes that the packets went missing.
All of these occurrences -- and more -- reduce throughput.
regds
prem
