Sending LAPD messages

The NMS ISDN stack must be in LAPD stack mode to send LAPD messages.

To send a LAPD message, the application builds an ISDN_MESSAGE structure specifying the message primitive and other data, as follows:

ISDN_MESSAGE field

Value

nai

Specifies the network access identifier (NAI) of the destination trunk.

from_ent

ENT_APPLI

Indicates that the message is sent from the application to the stack.

to_ent

ENT_DL_D

Indicates that the message is sent to the data link layer.

to_sapi

DL_SAPI_SIG

conn_id

1

code

Specifies the primitive of the LAPD message (for example DL_EST_RQ).

inf0, inf1, inf2, inf3, inf4

Reserved for internal data relay.

data_size

Specifies the size of the message buffer containing data associated with the message, if any.

nfas_group

Specifies the NFAS group number for this network access identifier (NAI). Used only if duplicate NAI values are defined.

userid

Not used.


If necessary, the application also builds a message buffer containing data to send.