Send Deregistration Notify before UDM modifies the UE context #25

YouShengLiu · 2023-08-17T10:18:54Z

If sending Deregistration Notify after UDM modifies the UE context, old AMF can't deregister for the UE.

* If sending Deregistration Notify after UDM modifies the UE context, old AMF can't deregister for the UE.

internal/sbi/producer/ue_context_management.go

ianchen0119 · 2023-09-12T04:15:50Z

internal/sbi/producer/ue_context_management.go

-
-		return nil, nil, nil
-	} else {
+	if oldAmf3GppAccessRegContext == nil {


I think this condition is unnecessary because the UDM sent the dereg notification to the old AMF.

When the UE is initially registered with the UDM through the AMF, it triggers the execution of this function block.

if old context was existed, it should reply StatusOK with new request in body

see #25 (comment)

tim-ywliu · 2023-09-12T06:39:04Z

internal/sbi/producer/ue_context_management.go

@@ -217,6 +217,22 @@ func RegistrationAmf3gppAccessProcedure(registerRequest models.Amf3GppAccessRegi
 		ue, _ := udm_context.Getself().UdmUeFindBySupi(ueID)
 		oldAmf3GppAccessRegContext = ue.Amf3GppAccessRegistration
 	}
+	// TS 23.502 4.2.2.2.2 14d: UDM initiate a Nudm_UECM_DeregistrationNotification to the old AMF
+	// corresponding to the same (e.g. 3GPP) access, if one exists
+	if oldAmf3GppAccessRegContext != nil {


why move dereg procedure here? oldAmf3GppAccessRegContext was already retrieved and will not be overwritten by new context.

@tim-ywliu @YouShengLiu

I think we can create the goroutine for sending deregistration notifications.

Yes, see #25 (comment)

tim-ywliu · 2023-09-12T07:10:24Z

internal/sbi/producer/ue_context_management.go

In HandleRegistrationAmf3gppAccessRequest():

// step 3: handle the message header, response, problemDetails := RegistrationAmf3gppAccessProcedure(registerRequest, ueID) // step 4: process the return value from step 3 if response != nil { if header != nil { // status code is based on SPEC, and option headers return httpwrapper.NewResponse(http.StatusCreated, header, response) } return httpwrapper.NewResponse(http.StatusOK, nil, response) } else if problemDetails != nil { ...

@YouShengLiu you missed this patch.

Ok, I will supplement it.

ianchen0119 · 2023-09-12T11:06:01Z

internal/sbi/producer/ue_context_management.go

+	// TS 23.502 4.2.2.2.2 14d: UDM initiate a Nudm_UECM_DeregistrationNotification to the old AMF
+	// corresponding to the same (e.g. 3GPP) access, if one exists
+	if oldAmf3GppAccessRegContext != nil {
+		deregistData := models.DeregistrationData{
+			DeregReason: models.DeregistrationReason_SUBSCRIPTION_WITHDRAWN,
+			AccessType:  models.AccessType__3_GPP_ACCESS,
+		}
+		// Deregistration Notify Triggered
+		pd := callback.SendOnDeregistrationNotification(ueID,
+			oldAmf3GppAccessRegContext.DeregCallbackUri,
+			deregistData,
+		)
+		if pd != nil {
+			return nil, nil, pd
+		}
+	}


// TS 23.502 4.2.2.2.2 14d: UDM initiate a Nudm_UECM_DeregistrationNotification to the old AMF // corresponding to the same (e.g. 3GPP) access, if one exists if oldAmf3GppAccessRegContext != nil { if !ue.SameAsStoredGUAMINon3gpp(*oldAmfNon3GppRegCtx.Guami) { deregistData := models.DeregistrationData{ DeregReason: models.DeregistrationReason_SUBSCRIPTION_WITHDRAWN, AccessType: models.AccessType__3_GPP_ACCESS, } // Deregistration Notify Triggered pd := callback.SendOnDeregistrationNotification(ueID, oldAmf3GppAccessRegContext.DeregCallbackUri, deregistData, ) if pd != nil { return nil, nil, pd } } }

Rewrite like this:

// TS 23.502 4.2.2.2.2 14d: UDM initiate a Nudm_UECM_DeregistrationNotification to the old AMF // corresponding to the same (e.g. 3GPP) access, if one exists if oldAmf3GppAccessRegContext != nil { if !ue.SameAsStoredGUAMI3gpp(*oldAmfNon3GppRegCtx.Guami) { deregistData := models.DeregistrationData{ DeregReason: models.DeregistrationReason_SUBSCRIPTION_WITHDRAWN, AccessType: models.AccessType__3_GPP_ACCESS, } logger.UecmLog.Infof("Send DeregNotif to old AMF GUAMI=%v", oldAmf3GppAccessRegContext.Guami) go func() { pd := callback.SendOnDeregistrationNotification(ueID, oldAmf3GppAccessRegContext.DeregCallbackUri, deregistData) // Deregistration Notify Triggered if pd != nil { logger.UecmLog.Errorf("RegistrationAmf3gppAccess: send DeregNotif fail %v", pd) } }() } return nil, &registerRequest, nil } else { header = make(http.Header) udmUe, _ := udm_context.Getself().UdmUeFindBySupi(ueID) header.Set("Location", udmUe.GetLocationURI(udm_context.LocationUriAmf3GppAccessRegistration)) return header, &registerRequest, nil }

This handler deals with the 3GPP access case. Why do we need to check the non-3GPP access context?

According to R15 TS 29.503 - 5.3.2.2.2 AMF registration for 3GPP access,

2a. On success, and if another AMF is registered for 3GPP access, the UDM updates the Amf3GppAccessRegistration resource by replacing it with the received resource information, and responds with "204 No Content".
UDM shall invoke the Deregistration Notification service operation towards the old AMF using the callback URI provided by the old AMF.

If the old Amf3GppAccessRegistration context exists, it should return "204 No Content" with an empty response body.

Hi @YouShengLiu

Please see TS 23.502 4.2.2.2.1 Step 14d:

When the UDM stores the associated Access Type (e.g. 3GPP) together with the serving AMF as indicated in
step 14a, it will cause the UDM to initiate a Nudm_UECM_DeregistrationNotification (see clause 5.2.3.2.2) to the old AMF corresponding to the same (e.g. 3GPP) access

So, we need to check whether the access type is 3GPP or not if there is the UECM context for the same UE.
If and only if yes, UDM sends the Nudm_UECM_DeregistrationNotification to the old AMF.

* Compare the old UECM context with the new one to determine whether to send a deregistration notification. * Use goroutine to send a deregistration notification to old AMF.

tim-ywliu · 2023-09-15T13:14:55Z

internal/sbi/producer/ue_context_management.go

+					logger.UecmLog.Errorf("RegistrationAmf3gppAccess: send DeregNotify fail %v", pd)
+				}
+			}()
+		}
 		return nil, nil, nil


should be

return nil, &registerRequest, nil

Ok, I will modify it.

…nNotification * Supplement the missed patch. * Add query parameters to differentiate whether the type is implicit or explicit.

tim-ywliu · 2023-10-01T09:00:59Z

@YouShengLiu
No need use queryParam, amf can determine to do implicit dereg by deregReason in DeregistrationDate.

- Remove the query parameter - Replace the DeregReason with UE_INITIAL_REGISTRATION, since it's triggered during the registration procedure

tim-ywliu · 2023-10-11T14:50:40Z

internal/sbi/producer/ue_context_management.go

-		callback.SendOnDeregistrationNotification(ueID, oldAmf3GppAccessRegContext.DeregCallbackUri,
-			deregistData) // Deregistration Notify Triggered
+		if !ue.SameAsStoredGUAMI3gpp(*oldAmf3GppAccessRegContext.Guami) {
+			deregistData := models.DeregistrationData{


modify as below:

// Based on TS 23.502 4.2.2.2.2, If the serving NF removal reason indicated by the UDM is Initial Registration, // the old AMF invokes the Nsmf_PDUSession_ReleaseSMContext (SM Context ID). Thus we give different // dereg cause based on registration parameter from serving AMF deregReason := models.DeregistrationReason_UE_REGISTRATION_AREA_CHANGE if request.InitialRegistrationInd { deregReason = models.DeregistrationReason_UE_INITIAL_REGISTRATION } deregistData := models.DeregistrationData{ DeregReason: deregReason, AccessType: models.AccessType__3_GPP_ACCESS, }

tim-ywliu · 2023-10-11T14:53:04Z

internal/sbi/producer/ue_context_management.go


-		return nil, nil, nil
+			logger.UecmLog.Infof("Send DeregNotify to old AMF GUAMI=%v", oldAmf3GppAccessRegContext.Guami)


move this logger into go routine.

… InitialRegistrationInd is true

Send Deregistration Notify before UDM modifies the UE context

a45917d

* If sending Deregistration Notify after UDM modifies the UE context, old AMF can't deregister for the UE.

tim-ywliu reviewed Sep 8, 2023

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internal/sbi/producer/ue_context_management.go Outdated Show resolved Hide resolved

Fix lint error

ed1d765

ianchen0119 reviewed Sep 12, 2023

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tim-ywliu reviewed Sep 12, 2023

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ianchen0119 reviewed Sep 12, 2023

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Modify RegistrationAmf3gppAccessProcedure

1e3da75

* Compare the old UECM context with the new one to determine whether to send a deregistration notification. * Use goroutine to send a deregistration notification to old AMF.

YouShengLiu requested a review from ianchen0119 September 15, 2023 05:30

ianchen0119 approved these changes Sep 15, 2023

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tim-ywliu reviewed Sep 15, 2023

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YouShengLiu mentioned this pull request Sep 18, 2023

Modify DeregistrationNotify free5gc/openapi#15

Closed

Modify HandleRegistrationAmf3gppAccessRequest and SendOnDeregistratio…

83c271b

…nNotification * Supplement the missed patch. * Add query parameters to differentiate whether the type is implicit or explicit.

Modify RegistrationAmf3gppAccessProcedure

f46e0a6

- Remove the query parameter - Replace the DeregReason with UE_INITIAL_REGISTRATION, since it's triggered during the registration procedure

tim-ywliu reviewed Oct 11, 2023

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deregReason should be DeregistrationReason_UE_INITIAL_REGISTRATION if…

dfcd551

… InitialRegistrationInd is true

tim-ywliu approved these changes Oct 12, 2023

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tim-ywliu merged commit 0f91e05 into free5gc:main Oct 12, 2023
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Send Deregistration Notify before UDM modifies the UE context #25

Send Deregistration Notify before UDM modifies the UE context #25

YouShengLiu commented Aug 17, 2023 •

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		return nil, nil, nil
		logger.UecmLog.Infof("Send DeregNotify to old AMF GUAMI=%v", oldAmf3GppAccessRegContext.Guami)

Send Deregistration Notify before UDM modifies the UE context #25

Send Deregistration Notify before UDM modifies the UE context #25

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