An Analysis of Alterations to the SCTP RTO Calculation Mechanism for WLAN Environments

As a connection oriented transport layer protocol the Stream Control Transmission Protocol (SCTP) inherits many of the features of the Transmission Control Protocol (TCP) including the mechanism by which Retransmission Timeout (RTO) is calculated. Previous investigations have established that the mechanism through which SCTP calculates RTO is inappropriate in Wireless LAN (WLAN) environments. This paper investigates the performance implications of changes to the SCTP RTO calculation mechanism. In particular alterations to the parameters α, the smoothing factor, and β, the delay variance factor are investigated. Results indicate that performance improvements are achievable through careful selection of α and β values. Throughput improvements of 63% over the default mechanism defined in RFC 4960 are described. These performance improvements however, while significant, still can not address the switchover delays which result from the distortions caused by continuously increasing RTT values in WLAN environments.

[1]  Yishay Mansour,et al.  Optimizing TCP Retransmission Timeout , 2005, ICN.

[2]  Lixia Zhang,et al.  Stream Control Transmission Protocol , 2000, RFC.

[3]  Jianfei Cai,et al.  Improving TCP performance during soft vertical handoff , 2005, 19th International Conference on Advanced Information Networking and Applications (AINA'05) Volume 1 (AINA papers).

[4]  Craig Partridge,et al.  Improving round-trip time estimates in reliable transport protocols , 1991, TOCS.

[5]  Seok Joo Koh,et al.  A scheme of primary path switching for mobile terminals using SCTP handover , 2007 .

[6]  Van Jacobson,et al.  Congestion avoidance and control , 1988, SIGCOMM '88.

[7]  Robert T. Braden,et al.  Requirements for Internet Hosts - Communication Layers , 1989, RFC.

[8]  Marc Necker,et al.  The Sensitivity of TCP to Sudden Delay Variations in Mobile Networks , 2004, NETWORKING.

[9]  Liam Murphy,et al.  SCTP Performance Issue on Path Delay Differential , 2007, WWIC.

[10]  Mohammed Atiquzzaman,et al.  Effect of delay spike on SCTP, TCP Reno, and Eifel in a wireless mobile environment , 2002, Proceedings. Eleventh International Conference on Computer Communications and Networks.

[11]  Vern Paxson,et al.  TCP Congestion Control , 1999, RFC.

[12]  Ramon Ferrús,et al.  An Analytical Estimation of the Failover Time in SCTP Multihoming Scenarios , 2007, 2007 IEEE Wireless Communications and Networking Conference.

[13]  Vern Paxson,et al.  Computing TCP's Retransmission Timer , 2000, RFC.

[14]  Andrei V. Gurtov.  Effect of Delays on TCP Performance , 2001, PWC.

[15]  Yuansong Qiao,et al.  SCTP Switchover Performance Issues in WLAN Environments , 2008, 2008 5th IEEE Consumer Communications and Networking Conference.

[16]  Van Jacobson,et al.  TCP Extensions for High Performance , 1992, RFC.

[17]  Jen Yi Pan,et al.  A Smart Path Failure Detection Method for SCTP in Wireless Network , 2007, 2007 International Conference on Wireless Communications, Networking and Mobile Computing.

[18]  Gabriel-Miro Muntean,et al.  Delay-Centric Handover in SCTP over WLAN , 2004 .