MTP: A Streaming-Friendly Transport Protocol

Today’s streaming applications typically use TCP or UDP to transmit media over the Internet. However, streaming over UDP is problematic due to firewalls that restrict UDP penetration and because of the potential for excessive congestion induced by unresponsive UDP flows. Streaming over TCP is also troublesome because media scaling is difficult given current TCP’s application programming interface (API) and because the TCP reliable in-order delivery requirement yields damaging media frame reception jitter. Recently proposed TCP-Friendly protocols have faced deployment resistance due to the firewall situation and the inability to demonstrate stability equivalent to that of TCP. To enhance TCP support for delay-sensitive streaming media, this paper proposes the Multimedia Transport Protocol (MTP), a unreliable data transport mode for TCP. MTP gracefully disables TCP retransmissions, uses delay-aware sender buffer queue management, and provides a transparent API that enables streaming media applications to make informed media scaling decisions. MTP is simple to implement, has the proven stability of TCP, and inherits the full benefit of network support for TCP. Through a simulation study that includes implementation and validation of a streaming media client and server, this paper shows that MTP offers streaming performance comparable to that provided by UDP, while doing so under a TCP-Friendly rate.