Performance analysis of The TCP SACK-based loss recovery mechanism (RFC 3517) under correlated losses

ABSTRACT

Most of the TCP/IP applications running over mobile communication systems such as GPRS, UMTS or CDMA1X-EV/DO use TCP as the transport protocol. The end-to-end performance of an application depends significantly on the performance of TCP. In particular, when a mobile device moves between two cells an entire burst of packets might be lost. How well TCP recovers from this type of scenario in which losses are highly correlated will greatly influence the end-to-end performance of the upper layer application. Correlated losses are also introduced by drop-tail buffers, which is the dominant packet drop policy implemented in mobile communication systems. In this paper we develop an analytical model to analyse the performance of the TCP SACK-based loss recovery mechanism defined in RFC 3517 under correlated losses imposed by mobility and/or drop-tail buffers. The results show that the mean TCP SACK throughput is no better than TCP Reno. Our model includes the details of the loss recovery phase, which helps us to show the low probability of having a successful SACK recovery phase and its potentially long recovery times

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INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.2 Network Protocols

General Terms:
Algorithms, Performance

Keywords:
SACK, TCP, performance modelling