Hello all,

I am trying to make a TCP to SCTP protocol translator with SCTP acting as the transport protocol over a high latency link. This will be implemented in an ip gateway PC which also does IP header compression before transmitting it over the high latency link.

For testing, I made a SCTP client to send 100 packets of 1000byte data to SCTP server listening on the other side of the high latency link. Now the issue I am facing is that I can send around 12 to 14 packets of 1000 bytes properly. After that the "Connection reset by peer" happens and because of that I am not able to send any more packets. Wireshark showed me that the otherside is sending an SCTP ABORT packet and thats why this issue is happening. But this issue is not seen if i try to send the packets from any PC connected to the gateway. Here everything goes fine.

In the gateway I have a tun tap device as the default gateway so all the packets are received by it and then IP compression is done and send off as UDP packets to the other gateway over the link. I have also configured SCTP heartbeat, rto max, min etc to suit the channel delay. For channel delay I use tc and netem available under linux. The delay is configured for about 500msec.

I am not sure if the lack of MAC address in the tun tap device is causing this issue ie the issue having to do with Linux security than with the SCTP library. I have attached the wireshark dump(of other gateway) for the working and failed conditions. Please let me know where I am going wrong. Also please let me know if anything is not clear in the issue or if you need more information.

Thanks for your help!

Regards,
Subin Martin