Evaluation of the QoS Offered by PRTP-ECN - A TCP-Compliant Partially Reliable Transport Protocol

Abstract

Abstract. The introduction of multimedia in the Internet imposes newQoS requirements on existing transport protocols. Since neither TCP nor UDP comply with these requirements, a common approach today is to use RTP/UDP and to relegate the QoS responsibility to the application. Even though this approach has many advantages, it also entails leaving the responsibility for congestion control to the application. Considering the importance of efficient and reliable congestion control for maintaining stability in the Internet, this approach may prove dangerous. Improved support at the transport layer is therefore needed. In this paper, a partially reliable transport protocol, PRTP-ECN, is presented. PRTP-ECN is a protocol designed to be both TCP-friendly and to better comply with the QoS requirements of applications with soft real-time constraints. This is achieved by trading reliability for better jitter characteristics and improved throughput. A simulation study of PRTP-ECN has been conducted. The outcome of this evaluation suggests that PRTP-ECN can give applications that tolerate a limited amount of packet loss significant reductions in interarrival jitter and improvements in throughput as compared to TCP. The simulations also verified the TCP-friendly behavior of PRTP-ECN.

TCP goes to hollywood

“…Many other transport protocols have been designed, including SCTP [23] and DCCP [14], that offer novel delivery models, and Partially Error Controlled Connection (PECC) [6] and PRTP-ECN [8], that improve support for multimedia applications in particular.…”

TCP Hollywood: An unordered, time-lined, TCP for networked multimedia applications

“…Transport protocols that rely on application-layer metadata to improve performance include Partially Error Controlled Connection (PECC) [25] and PRTP-ECN [26]. Other protocols such as SCTP [7] and DCCP [8] were engineered to broaden the delivery models offered by the transport-layer.…”

Taxonomy and survey of retransmission-based partially reliable transport protocols

“…As a matter of fact, we know of only two protocols: SRP [27] and PRTP-ECN [17,18]. SRP primarily targets audio applications, and PRTP-ECN has been used to improve the transmission of images on Web pages.…”

“…Table 1 shows how the following protocols are classified: Slack ARQ [13], PECC [11,12], k-XP [3,22], POCv2 [10], AOEC [16], CUDP [32], VDP [8], Jacobs/Eleftheriadis [20], TLTCP [24], SRP [27], Papadopoulos/Parulkar [25], SR-RTP [15], HPF [21], MSP [19], XUDP [4], PR-SCTP [33], and PRTP-ECN [17,18]. A survey of a subset of these protocols is also presented: PECC, POCv2, SRP, HPF, PR-SCTP, and PRTP-ECN.…”

“…PRTP-ECN is an extension to TCP suggested by Grinnemo et al [17,18] that aims to make TCP better suited for applications with soft real-time constraints (e.g., best effort multimedia applications). In particular, PRTP-ECN is an attempt to make this traditionally congestion insensitive class of applications aware of congestion.…”