On Jan 2, 2012, at 7:48 PM, daniel migault wrote:

> Hi,
>
> We test SCTP multihoming with FTP. "withsctp tnftpd -4D" starts the server, and "withsctp ftp" starts the client with its two network interfaces. FTP initiates first a SCTP association for the control connection on port 21, followed by a second SCTP association for the data connection on port 20.

It looks like you are using Linux specific stuff in combination with the Linux kernel
implementation. Is that right?

This list supports the sctplib user land SCTP implementation. So you might want to
ask this question on the LKSCTP mailing list.

>
> When establishing its SCTP association for the control connection the INIT has the two IPv4 address parameter payloads.  This not the case for the second SCTP association where the client does not announce any IPv4 address parameter for the data connection.

So I guess that the socket is bound to a specific address. Then you wouldn't see any address in the INIT chunk.
So you might need to change the ftp code...

>
> We would like the second SCTP association to have two IPv4 address parameters so to measure multihoming during the data transfer. We are running "withsctp" on Fedora for the client and Debian for the server.
>
> Has anyone any clue how to force the second SCTP association to have two IPv4 address parameters? Are there any specific values to be set with sysctl?
>
> Regards,
>
> Daniel

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