Time-lined TCP for the TCP-friendly delivery of streaming media

Abstract

This paper introduces Time-lined TCP (TLTCP). TLTCP is a protocol designed to provide TCP-friendly delivery of time-sensitive data to applications that are loss-tolerant, such as streaming media players. Previous work on unicast delivev of streaming media over the Internet proposes using UDP and performs congestion control at the user level by regulating the application's sending rate (attempting to mimic the behavior of TCP in order to be TCP-friendly). TLTCP, on the other hand, is intended to be implemented at the transport level, and is based on TCP with modifications to support time-lines. Instead of treating all data as a byte stream TLTCP allows the application to associate data with deadlines. TLTCP sends data in a similar fashion to TCP until the deadline for a section of data has elapsed; at which point the now obsolete data is discarded in favor of new data. As a result, TLTCP supports TCP-friendly delivery of streaming media by retaining much of TCP 's congestion control functionality. We describe an API f o r TLTCP that involves augmenting the recvmsg and sendmsg socket calls. We also describe how streaming media applications that use various encoding schemes like MPEG-1 can associate data with deadlines and use TLTCP's API. We use simulations to examine the behavior of TLTCP under a wide range of networks and workloads. We find that it indeed performs time-lined data delivery and under most circunzstunces bandwidth is shared equally among conipeting TLTCP and TCP Jlows. Moreover, those scenarios under which TLTCP appears to be unfriendly are those under which TCPJEows competing only with other TCPJlows do not share bandwidth equitably,

Receiver-driven bandwidth sharing for TCP

“…Traditionally most streaming applications have been implemented using UDP coupled with a rate control protocol which ensures fairness with TCP traffic [17]. However, there have been several recent proposals, [14], [18], and [19], which challenge the conventional wisdom that TCP is unsuitable for multimedia streaming. Our proposed system shares this goal of providing effective video streaming over TCP.…”

TCP goes to hollywood

“…Middleboxes in the network perform functions that make assumptions about the behaviour of TCP hosts, and reset connections when unexpected behaviour is observed. As an example, TLTCP [17] creates holes in the TCP sequence space. When a middlebox observes an incomplete sequence space, it assumes that the sender is misbehaving, and closes the connection.…”

“…Time-Lined TCP (TLTCP) [17], for example, allows applications to express timelines for messages, with data only transmitted during its timeline. In Minion [18], applications can replace unsent messages in the sending buffer.…”

Implementing Real-Time Transport Services over an Ossified Network

“…Time-Lined TCP (TLTCP) [17] similarly provides a message-oriented service, but allows applications to attach a time-line to messages. Messages are (re-)transmitted as under standard TCP within their time-line, after which they are discarded.…”