Enabling PVM to exploit the SCTP protocol

Recently, a new general purpose transport protocol, called SCTP, has been standardized by the IETF to be used in IP based applications. The features of SCTP, compared with TCP, better support the communication requirements of parallel applications and have motivated the development of SCTP-PVM, a PVM extension, that uses SCTP for direct communications among tasks. Using the LK-SCTP open source kernel module implementation of SCTP, we have compared the performances of SCTP-PVM with the standard version of PVM that, through the PvmRouteDirect directive, uses TCP. Due to the vast difference in the maturity level of both protocols where TCP, unlike SCTP, is able to offload checksum calculations and transport segmentations in hardware, in the tests performed, we have disabled the TCP hardware transport segmentations and we have analyzed the behaviour of SCTP-PVM both with the checksum enabled and disabled. SCTP-PVM, with the checksum disabled, resulted better as the messages exchanged among tasks increase. In addition, thanks to the SCTP multi-streaming feature, SCTP-PVM achieved higher throughput in error prone networks. On the other hand, due to the high-protocol processing cost of the checksum enabled, SCTP-PVM resulted slower. Finally, the SCTP-PVM extension has been designed to easily enable existing PVM applications to use the SCTP protocol features.