The Stream Control Transmission Protocol (SCTP) as defined in RFC 4960 is an advanced Transport Layer protocol that provides support for multi-homing. That is, SCTP endpoints may simultaneously use multiple Network Layer addresses, which allows to connect the endpoints to multiple networks for redundancy purposes. However, for the transfer of user data, only one of the possible paths is currently used at a time. All other paths remain as backup and are only used for retransmissions. Clearly, the existence of multiple paths has led to the idea of applying load sharing among the paths. An extension to SCTP -- denoted as Concurrent Multipath Transfer (CMT) -- realises this load sharing functionality. While this approach works well for similar paths, i.e. paths having similar characteristics regarding bandwidths, bit error rates and delays, the use of dissimilar paths does not work that neatly.

The focus of our research on SCTP is the optimisation of Concurrent Multipath Transfer (CMT), which means to simultaneously utilise multiple paths within the network to increase the application data throughput. This particularly also includes topics like congestion control and the fairness of resource sharing.

For further information on SCTP and the details of the project, see Thomas Dreibholz's SCTP Page at http://www.uni-due.de/~be0001/sctp/ .