Impact of out-of-sequence processing on the performance of data transmission

Application Level Framing (ALF) was proposed by Clark and Tennenhouse as an important design principle for developing high performance applications. A LF relies in part on the ability of applications and protocols to process p ackets independently one from the other. Thus, performance gains one might expect from the use of ALF are clearly related to performance gains one mig ht expect from applications that can handle and process packets received ou t-of-sequence, as compared to application that require in-sequence delivery (FTP, TELNET, etc.). In this paper, we examine how the ability to process out-of-sequence packets impacts the efficiency of data transmission. We con sider both the impact of application parameters such as the time to process a packet by the application, as well as network parameters such as network transmission delay, network loss rate and flow and congestion control char acteristics. The performance measure of interest are total latency, buffer requirements, and jitter. We show, using experimental and simulation result s, that out-of-sequence processing is beneficial only for very Limited rang es of transmission delays and application processing time. We discuss the i mpact of this on the architecture of communication systems dedicated to dis tributed multimedia applications. (C) 1999 Elsevier Science B.V. All rights reserved.