Reliable Data Transfer: Sliding Window

Pipelining

Applications may generate data at a rate much higher than the network can transport it. Processor speed is generally much higher than the speed of writing out and reading data to/from the network (I/O).

Furthermore, reliable message communication is a multi-step process:

1. The processor emits the message to be sent, the network carries the message to the destination.
2. The receiver processor receives and emits an acknowledgment message.
3. The network carries the acknowledgment to the sender. So, instead of waiting for an acknowledgment of every packet before transmitting the next one, it’s more efficient to pipeline the multi-step process. In other words, instead of waiting for the acknowledgment of a message before transmitting the next one, the sender keeps transmitting messages without waiting for an acknowledgment. This makes more efficient use of the processor’s time.

While pipelining allows the sender to transmit segments at a higher rate, it may cause the receiver to become overloaded because the receiver may be running on a slower machine than the sender, or the receiving machine may be busy executing other processes.

Note: “stop and wait” is the term used in literature for ...