This chapter presents various congestion control schemes for transport protocols together with a number of metrics for the evaluation of these protocols with special emphasis on fairness-related measures. The paper analyzes some properties of the TFRC algorithm, which provides applications with congestion control mechanisms that can be applied for streaming media. Streaming media is a delivery method of media content, which is simultaneously received by, and displayed to, the end-user while it is being delivered by the provider.
Key Terms in this Chapter
TCP (Transmission Control Protocol): Widely used for bulk data transmission. It is suitable for file transfer, but not for streaming media transmission.
Transport Layer: This is an abstraction; the protocol belonging to the transport layer is responsible for the port handling and sometimes the improved reliability of the transmission.
Data Stream Applications: The class of large receiver set, low bandwidth real-time data applications.
Reliability: The improved quality of data transmission. Different types of reliability exist, including data accuracy, or real-time delivery.
Congestion Control: A mechanism that can be built into a protocol. Its main goal is to help the data transmission avoid the buffer overflow in the network routers.
Max-Min Fairness: The principle of max-min fairness allocates network resources in such a way that the bit rate of a flow cannot be increased without decreasing the bit rate of a flow having a smaller bit rate.
Pareto Efficiency: A resource allocation is said to be Pareto efficient if all resources are consumed in the sense that the bit rate allocated to one flow cannot be increased without decreasing the bit rate allocated to another flow.
Port Handling: From the network, the processes running in a computer that can be addressed with an integer number between 0...65535 is called a port. Some port numbers are mapped steadily to important applications. They are called well-known port numbers. E.g., the Web server typically uses the port number 80.
Goodput: The bandwidth of the useful packets at the receiver side, which is also called the effective receiving rate.
Round Trip Time (RTT): The time period that is necessary for sending a packet from the sender to the receiver and for sending it from the receiver back to the sender.