Flow Control

  The main task of flow control is to protect the receiver from an unmanageable flood of packets and from consequent data loss due to reception buffer overflow. For that purpose, senders and receivers can reach traffic agreements that are independent from the underlying communication system.

There are two main approaches to flow control:

Window-Based Flow Control.

  Window-based systems work with respect to the maximum amount of data that the sender is allowed to sent without having received an acknowledgement for data already transmitted. The sizes of both sending and reception windows must be adapted to the participants' capacities and to the characteristics of a particular network.

Rate-Based Flow Control.

  In a rate-based system, a sender forwards data at a reasonable rate that is chosen in order to allow network and receivers to cope with the transmitted volume. Rate-controlled systems do not necessarily enforce an acknowledgement of the received data. However, some feedback about the current transmission quality is useful for adaptive systems that allow media scaling.