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Transport Provider Interface (TPI), Version 2 Draft 2
Copyright © 1999 The Open Group


T_DISCON_REQ - Disconnect Request


This message consists of one M_PROTO message block followed by one or more M_DATA message blocks if there is any user data specified by the transport user. The format of the M_PROTO message block is as follows:

struct T_discon_req {
    t_scalar_t   PRIM_type;      /* Always T_DISCON_REQ */
    t_scalar_t   SEQ_number;


This primitive requests that the transport provider deny a request for connection, or disconnect an existing connection.



identifies the primitive type.


identifies the outstanding connect indication that is to be denied. If the disconnect request is disconnecting an already existing connection, then the value of SEQ_number will be ignored.


This primitive requires the transport provider to generate the following acknowledgment on receipt of the primitive, and the transport user must wait for the acknowledgment before issuing any other primitives:


Correct acknowledgment of the primitive is indicated via the T_OK_ACK primitive described in reference TPI-SMD.

Non-fatal errors

These errors will be indicated via the
T_ERROR_ACK primitive described in reference TPI-SMD.


The allowable errors are as follows:


The amount of user data specified was invalid.


The sequence number specified in the primitive was incorrect or invalid.


This primitive is not supported by the transport provider.


The primitive would place the transport interface out of state.


A system error has occurred and the UNIX system error is indicated in the primitive.


Only connection-mode.


Transport user.

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