Using DCCP: Issues and improvements

The Datagram Congestion Control Protocol (DCCP) is no longer too young to be usable: the first RFCs were published in 2006, and a stable and quite complete Linux implementation exists. DCCP over UDP has also recently been specified to address network traversal problems. But how good is the service provided to applications by this protocol? This paper identifies some deficiencies of the current implementation - the lack of transparency in the API with regard to packet loss, the coarse granularity of the lookup table used to calculate the TFRC equation, and the lack of history discounting in CCID-3 - and demonstrates that they can significantly impair the performance of typical DCCP use cases such as live video streaming. Solutions are proposed to tackle all these problems, and it is shown that they considerably improve the performance and the flexibility of applications.