Sun Microsystems 3U manual Figure C-2Message Format, Table C-2Fields in the Mproto mblock

The Q.93B driver is an M-to-N mux STREAMS driver. Multiple application programs can be plumbed above the driver, and multiple physical interfaces can be connected below Q.93B. Applications can access any or all of the physical interfaces, and messages received on the physical interfaces can be directed to any of the applications. To direct messages through the Q.93B driver, messages from applications must include a physical interface name to identify the outgoing interface and an SAP to identify the application to which the message should be directed on the receiving host.

Send messages to Q.93B by applications according to the format illustrated in FIGURE C-1; kernel applications use putnext(9f) to send the mblocks shown, and user applications send two corresponding strbufs using putmsg(2).

M_PROTO

mp

Ifname

Call_ID

Type

Error_Code

Call_Tag

FIGURE C-2Message Format

		M_DATA
Q.2931	Message
				R
				S
	Information			V
	Elements (IEs)
(9)
			(16)

TABLE C-2Fields in the M_PROTO mblock

Message	Explanation
Ifname	Null-terminated string containing the device name
Call_ID	Unique number from Q.93B for each interface.
Type	Same as the Q.2931 message type except there is a local non-Q.2931
	message type SETUP_ACK. The SETUP_ACK message is used to provide
	the Call_ID to the user.
Error_Code	Error returned from Q.93B when an erroneous message is received from
	the user. The same mblock chain is returned to the user with the
	Error_Code field set. The user must always clear this field
Call_Tag	Number assigned by the calling application layer to a SETUP message.
	When a SETUP_ACK is received from Q.93B, the Call_ID has been set;
	use the Call_Tag field to identify the acknowledgment (ack) with the
	original request. From that point on, use the Call_ID value to identify
	the call.

The structure included in the M_PROTO mblock is defined as the qcc_hdr_t structure in the <atm/qcctypes.h> header file. In the second mblock, the Q.2931 header portion (9 bytes) of the Q.2931 message is blank and is later filled in by the

Appendix C Application Programmer’s Interface 91