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Data Link Provider Interface (DLPI), Version 2
Copyright © 2000 The Open Group


DL_CONNECT_REQ (dl_connect_req_t) - requests the DLS provider establish a data link connection with a remote DLS user. The request contains the DLSAP address of the remote (called) DLS user and quality of service parameters to be negotiated during connection establishment.


The message consists of one M_PROTO message block containing the structure shown below.

typedef struct {
    t_uscalar_t  dl_primitive;
    t_uscalar_t  dl_dest_addr_length;
    t_uscalar_t  dl_dest_addr_offset;
    t_uscalar_t  dl_qos_length;
    t_uscalar_t  dl_qos_offset;
    t_uscalar_t  dl_growth;
} dl_connect_req_t;


LI dl_primitive


conveys the length of the DLSAP address that identifies the DLS user with whom a connection is to be established. If the called user is implemented using DLPI, this address is the full DLSAP address returned on the DL_BIND_ACK.


conveys the offset from the beginning of the M_PROTO message block where the destination DLSAP address begins.


conveys the length of the quality of service (QOS) parameter values desired by the DLS user initiating a connection. The desired QOS values are conveyed in the appropriate structure defined in QOS Data Structures. A full specification of these QOS parameters and rules for negotiating their values is presented in Quality of Data Link Service.

If the DLS user does not wish to specify a particular QOS value, the value DL_QOS_DONT_CARE may be specified. If the DLS user does not care to specify any QOS parameter values, this field may be set to zero.


conveys the offset from the beginning of the M_PROTO message block where the quality of service parameters begin.


defines a growth field for future enhancements to this primitive. Its value must be set to zero.


The message is valid in state DL_IDLE.


The resulting state is DL_OUTCON_PENDING.


There is no immediate response to the connect request. However, if the connect request is accepted by the called DLS user, DL_CONNECT_CON is sent to the calling DLS user, resulting in state DL_DATAXFER. If the connect request is rejected by the called DLS user, the called DLS user cannot be reached, or the DLS provider and/or called DLS user do not agree on the specified quality of service, a DL_DISCONNECT_IND is sent to the calling DLS user, resulting in state DL_IDLE. If the request is erroneous, message DL_ERROR_ACK is returned and the resulting state is unchanged.



The DLS user did not have proper permission to use the requested DLSAP address.


The destination DLSAP address was in an incorrect format or contained invalid information.


The quality of service parameters contained invalid values.


The quality of service structure type was not supported by the DLS provider.


The primitive was issued from an invalid state.


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

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