DL_UNITDATA_IND Primitive

Communications Technical Reference, Volume 1

DL_UNITDATA_IND Primitive

Purpose

Conveys one data link service data unit (DLSDU) from the data link service (DLS) provider to the DLS user.

Structure

The message consists of one M_PROTO message block, which contains the following structure, followed by one or more M_DATA blocks containing at least one byte of data:

typedef struct 
{
   ulong dl_primitive;
   ulong dl_dest_addr_length;
   ulong dl_dest_addr_offset;
   ulong dl_src_addr_length;
   ulong dl_src_addr_offset;
   ulong dl_group_address;
} dl_unitdata_ind_t;

This structure is defined in /usr/include/sys/dlpi.h.

Description

The DL_UNITDATA_IND primitive conveys one DLSDU from the DLS provider to the DLS user.

Note: The amount of user data that may be transferred in a single DLSDU is limited. This limit is conveyed by the dl_max_sdu parameter of the DL_INFO_ACK primitive.

Parameters

dl_primitive	Specifies the DL_UNITDATA_IND primitive.
dl_dest_addr_length	Specifies the length of the data link service access point (DLSAP) address of the destination DLS user. If the destination user is implemented using the Data Link Provider Interface (DLPI), the full DLSAP address is returned on the DL_BIND_ACK primitive.
dl_dest_addr_offset	Indicates where the destination DLSAP address begins. The value of this parameter is the offset from the beginning of the M_PROTO message block.
dl_src_addr_length	Specifies the length of the DLSAP address of the source DLS user.
dl_src_addr_offset	Indicates where the source DLSAP address begins. The value of this parameter is the offset from the beginning of the M_PROTO message block.
dl_group_address	Indicates the address set by the DLS provider upon receiving and passing upstream a data message when the destination address of the data message is a multicast or broadcast address.

States

Valid	The primitive is valid in the DL_IDLE state.
New	The resulting state is unchanged.

Implementation Specifics

This primitive is part of Base Operating System (BOS) Runtime.

Related Information

The DL_INFO_ACK primitive, DL_BIND_ACK primitive, DL_UDERROR_IND primitive.