SCTP_UNORDERED = 1, /* Send/receive message unordered. */
SCTP_ADDR_OVER = 2, /* Override the primary destination. */
SCTP_ABORT=4, /* Send an ABORT message to the peer. */
+ SCTP_SACK_IMMEDIATELY = 8, /* SACK should be sent without delay */
SCTP_EOF=MSG_FIN, /* Initiate graceful shutdown process. */
};