Title: ADS - Erroneous exception handling for D-START confirmation

PDR Reference:                              	98050007
Originator Reference:                          	ATNSI_ADS04 
SARPs Document Reference:                  	ADS SARPs, Section 2.2.1.5.4.3.2
Status:                                        	REJECTED 
PDR Revision Date:                             	11/06/98 (SUBMITTED -> REJECTED)
PDR Submission Date:                           	12/05/98 
Submitting State/Organization:                 	AIRSYS ATM (ACI/ATNSI)
Submitting Author Name:                        	Ilkiewicz, M /  Stokes, S.
Submitting Author E-mail Address:           					michel.ilkiewicz@cdv.vly.sextant.thomson.fr 
					Shawn.Stokes@ATNSI.COM 
Submitting Author Supplemental 
Contact Information:                       
SARPs Date:                                   	IV1.1 
SARPs Language:                            	English

Summary of Defect:

The LI module does not request the AB module to abort with reason invalid-PDU on receipt of a D-START confirmation containing an ADS-positive-acknowledgement PDU with a request type equal to cancel-event-contract, cancel-periodic-contract or modify-emergency contract.

The LI module does not request the AB module to abort with reason invalid-PDU on receipt of a D-START confirmation containing an ADS-negative-acknowledgement PDU with a request type equal to cancel-event-contract, cancel-periodic-contract or modify-emergency contract.

This is erroneous, since a SARPs conformant air ASE does not send these PDUs in a D-START response.

Assigned SME:                              		Sub-Volume II SME

Proposed SARPs amendment: 

The list of valid APDUs in D-START confirmations which do not lead the LI module to request the AB module to abort with reason invalid-PDU should be reduced by excluding ADS-positive-acknowledgement PDUs with a request type equal to cancel-event-contract, cancel-periodic-contract or modify-emergency contract and by excluding ADS-negative-acknowledgement PDUs with a request type equal to cancel-event-contract, cancel-periodic-contract or modify-emergency contract.

SME Recommendation to CCB: 

In Section 2.2.1.5.4.3.2, the ground LI module is filtering the PDUs which are not allowed to be present in the User Data parameter of the D-START confirmation parameter. The ADS-positive-acknowledgement PDU and the ADS-negative-acknowledgement PDU are allowed. Therefore they can not be rejected with reason "invalid-PDU".

Actually, the validity of the values in the PDU fields is then checked by the ground EC, PC and EM modules. If  
the PDU on receipt of a D-START confirmation contains an ADS-positive-acknowledgement PDU or an ADS-negative-acknowledgement PDU with a request type equal to cancel-event-contract, cancel-periodic-contract or modify-emergency contract is passed to these modules, these modules will detect an out of sequence situation (i.e. invalid state). Section 2.2.1.5.4.4.1 applies (abort with reason "sequence-error").

With the current specifications, the error situation described in this PDR is detected by the ADS protocol machine and the dialogue is aborted with the correct abort reason. There is no reason to modify the SARPs.

CCB Decision:              			atnp_ccb_chair: SUBMITTED (12/05/98)
					atnp_ccb_chair: REJECTED (11/06/98)