Hi

We have been testing different primitive handover scenarios using SCTP by using the SetRemotePath implementation in sctplib 1.1.6, and have come up with an unexpected result. The setup is as follows: A server running a modified version of the daytime servers, which repeatedly sends out SCTP packets with predefined inter packet time, when an association is created and until the association is shutdown. The server only got one NIC. A node which is running a slightly modified version of the terminal, and which haves two NIC located in two different subnets, is creating an association with the server, where both IP addresses of the NICs are added. During the association the node sends a SetRemotePrimary (SETPRIM through the terminal) so the connection is handed over to the other interface. The problem is that when changing from NIC1 to NIC2 the handover time is approximately 0.1s with a low variance, but when changing from NIC2 to NIC1 the handover time is 3s with a low variance. The problem is to explain why it takes exactly 3s before the handover is carried out? Is it some timer in sctplib that causes this? It should be said that there are differences in the handling of NIC1 and NIC2 since one is Bluetooth and the other is WLAN, and this will probably explain why the 3s gap only occurs in one direction, but what I causing the 3s?

Another (shorter) question: Is there a plan for when ADD_IP and DELETE_IP to/from an association will be implemented into sctplib?

Regards

Thorbjørn Jørgensen

Group 681 Aalborg University