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LAPD Example Call Flows

TEI Denied Procedure

The procedure below shows an ID Request from the user side, requesting TEI 11. Management checks the Configuration database but cannot find TEI 11 listed, so it issues an ID Denied. Management sends a PPL Event Indication message to the local host to indicate that this TEI failed assignment procedures.

TEI Already Assigned Procedure

The procedure below shows a check procedure being initiated when a TEI is already assigned. The ID Check Response message returns the same TEI, and the TEI failure is propagated to the host.

Host State Query

The figure below illustrates a query for the state of a specific TEI/SAPI combination on a D channel. The PPL Event Request message contains the following:

• LAPD Status ICB

• addresses a slot

• D channel number

• SAPI

• TEI

The result appears in a PPL Event Indication message containing an LAPD Status ICB.

See Programmable Protocol Language.
A computer, attached to the Excel platform through an RS-232 or Ethernet link, from which you run the telecommunications application that controls the Excel platform.
The condition of a component at a given instant. The current "context" of a PPL object, such as Idle, Seizing, Answered. In PPL files, a State is represented by a circle.
A condition that, when met, drives a state machine from one state to another. A condition that drives a Component out of its current state by invoking an associated primitive.
Link Access Protocol (Procedure) – D channel (ISDN)
See Information Control Block.