Title: FIS - Actions upon LI-1 Timer Expiration

PDR Reference:                   		98120011
Originator Reference:                  	acifis06 
SARPs Document Reference:              	FIS SARPs, Section 2.4.5.3.12.17.1 and 
							Table 2.4.5-10/a
Status:                                  	RESOLVED
Impact:						C (Clarification)          
PDR Revision Date:                    	21/01/99 (PROPOSED -> RESOLVED)
							19/01/99 (ACCEPTED -> PROPOSED)
							14/12/98 (SUBMITTED -> ACCEPTED)       
PDR Submission Date:                 	03/12/98
Submitting State/Organization:         	AIRSYS ATM (ACI) 
Submitting Author Name:                	Ilkiewicz, M / Stokes, S 
Submitting Author E-mail Address:      	michel.ilkiewicz@cdv.vly.sextant. 
							thomson-csf.com,Shawn.Stokes@ATNSI.COM
Submitting Author Supplemental 
Contact Information:                       
SARPs Date:                           	IV2.2, IV2.3 (Doc 9705 Ed1)
SARPs Language:                        	English

Summary of Defect:

Upon expiration of the LI-1 timer, the FIS LI should ask the AB process to Abort with reason "timerExpiration" and then remain in the same state. Section 2.4.5.3.12.17.1 and table 2.4.5-10/a should be updated to reflect this action upon LI-1 timer expiry rather than the action that is currently stated.

Section 2.4.5.3.12.17.1 indicates that the FIS LI module should invoke a D-ABORT request primitive with "user" for the Originator when the LI-1 timer has expired.  This is incorrect, because the Abort is not originated by the FIS ASE user, but rather by the FIS ASE (so it really is a "provider" abort rather than a "user" abort).  In addition, this is inconsistent with all other cases where the LI determines that it should Abort (e.g., see section 2.4.5.3.12.13.1).  In all other cases, LI asks the AB process to Abort with the appropriate Abort Reason (which results in a "provider" originated D-ABORT request).

In addition, if the originator of the D-ABORT request is "user" in this scenario, then the remote peer receiving the corresponding D-ABORT indication is incorrectly informed that the Abort was due to its peer "user" and not due to timer expiry within its peer "ASE".  Consequently, any network management attributes or statistics being kept related to this information would be incorrect.

Assigned SME:                              Sub-Volume II SME

Proposed SARPs amendment: 

1/  Section 2.4.5.3.12.17.1 should be changed from:
If in LI-END-I state, the LI module shall:
a) invoke the D-ABORT request primitive with the abstract value "user" as the <Originator> parameter, and 
b) enter the LI-IDLE state.

to:
If in LI-END-I state, the LI module shall:
a) request the AB module to abort with the reason "timer expiration", and 
b) remain in the LI-END-I state.


2/  Table 2.4.5-10/a, replace cell (t-LI-1, LI-END-I), with:   
AB-abort ("timer expiration")
-> LI-END-I

SME Recommendation to CCB: 			-

In theory, the analysis above is correct. However, the D-END exchanged is performed by the FIS-air-ASE and the FIS-ground-ASE with NO involvement of the FIS-users. There is NO active FIS-user any more, therefore there is no need to indicate to the local or the peer FIS-user that the local ASE has aborted on t-LI-1 timeout. The abort is only performed to release on both sides the resources and there is no reason to send an Abort PDU on the line. This is why a simple abort (with meaningless parameters and without an Abort APDU) is invoked by the FIS-air-ASE.

If the new requirement that this abort reason could be used and logged for Systems Management purpose is confirmed, it is necessary to adopt the resolution presented in this PDR. 

CCB Decision:                         	atnp_ccb_chair (SUBMITTED): 03/12/98
							atnp_ccb_chair (ACCEPTED): 14/12/98
							CCB-8a (Honolulu): RESOLVED (21/01/99)