SCTP Initiation Structure (SCTP_INIT)

When an application calls sendmsg()() using a one-to-many style socket API, it uses an SCTP initiation structure to set the protocol parameters for a new association. The SCTP initiation structure is represented by the sctp_initmsg ancillary data structure. The name of the ancillary data type is SCTP_INIT, and the data type is defined at the IPPROTO_SCTP level.

Following is the data structure for the sctp_initmsg structure:

struct sctp_initmsg {
 uint16_t sinit_num_ostreams;
 uint16_t sinit_max_instreams;
 uint16_t sinit_max_attempts;
 uint16_t sinit_max_init_timeo;
};

where:

sinit_num_ostreams

    Represents the number of outbound streams.
sinit_num_ostreams

    Represents the number of inbound streams to be supported.
sinit_max_instreams

    Represents the maximum number of times INIT must be transmitted before giving up an association setup.
sinit_max_init_timeo

    Represents the largest time out value to use in attempting a INIT.

The values provided by an application are for a association and overrides the default values.

參考資料：
SCTP Ancillary Data Structures