isdn_msg_hdr(D4isdn)

isdn_msg_hdr -- ISDN message header

Synopsis

   #include <sys/types.h>
   #include <sys/scoisdn.h>
   
   typedef struct isdn_msg_hdr
   {
       isdnDword_t DL_prim;
       isdnWord_t  Length;
       isdnWord_t  AppID;
       isdnByte_t  Cmd;
       isdnByte_t  SubCmd;
       isdnWord_t  MsgNum;
   } isdn_msg_hdr_t;

Description

The ISDN message header structure isdn_msg_hdr is included the control portion of an ISDN message in Section D7isdn manual pages. Message parameters (as described in Section D4isdn manual pages in Section D4isdn manual pages) are coded in the control portion following the isdn_msg_hdr.

Structure members

DL_prim: The DLPI primitive for ISDN is always set to DL_ISDN_MSG.
Length: total length of the message, including the complete message header but excluding the DLPI primitive.
AppID: application identifier. The ISDN driver assigns an application number to an application through the ISDN_REGISTER ioctl.
Cmd: command, or message type (for example, ALERT, CONNECT, etc.)
SubCmd: subcommand, or message extension (for example, _REQ, _CONF, _IND or _RESP)
MsgNum: message number, included with each message. The ISDN driver will always return the number used in the REQUEST message with the corresponding CONFIRMATION. Applications may choose unique message numbers to identify message correlations before interpreting incoming messages. INDICATIONs from the driver will be numbered so that an application is guaranteed to get different message numbers for every incoming INDICATION.

References

Intro(D4isdn), Intro(D7isdn)

``SCO ISDN adapter drivers'' in Developing MDI network adapter drivers.