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Send Deregistration Notify before UDM modifies the UE context #25

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merged 6 commits into from
Oct 12, 2023
Merged

Send Deregistration Notify before UDM modifies the UE context #25

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a45917d
Send Deregistration Notify before UDM modifies the UE context
YouShengLiu Aug 14, 2023
ed1d765
Fix lint error
YouShengLiu Sep 8, 2023
1e3da75
Modify RegistrationAmf3gppAccessProcedure
YouShengLiu Sep 15, 2023
83c271b
Modify HandleRegistrationAmf3gppAccessRequest and SendOnDeregistratio…
YouShengLiu Sep 18, 2023
f46e0a6
Modify RegistrationAmf3gppAccessProcedure
YouShengLiu Oct 8, 2023
dfcd551
deregReason should be DeregistrationReason_UE_INITIAL_REGISTRATION if…
tim-ywliu Oct 12, 2023
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30 changes: 18 additions & 12 deletions internal/sbi/producer/ue_context_management.go
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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 {
	...

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@YouShengLiu you missed this patch.

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Ok, I will supplement it.

Original file line number Diff line number Diff line change
Expand Up @@ -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 {
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why move dereg procedure here? oldAmf3GppAccessRegContext was already retrieved and will not be overwritten by new context.

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@tim-ywliu @YouShengLiu

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

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@tim-ywliu tim-ywliu Sep 13, 2023 •
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Yes, see #25 (comment)

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
}
}
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@ianchen0119 ianchen0119 Sep 12, 2023 •
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	// 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
            }
        }
	}

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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
	}

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

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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.

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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.


udm_context.Getself().CreateAmf3gppRegContext(ueID, registerRequest)

Expand Down Expand Up @@ -245,23 +261,13 @@ func RegistrationAmf3gppAccessProcedure(registerRequest models.Amf3GppAccessRegi
}
}()

// 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,
}
callback.SendOnDeregistrationNotification(ueID, oldAmf3GppAccessRegContext.DeregCallbackUri,
deregistData) // Deregistration Notify Triggered

return nil, nil, nil
} else {
if oldAmf3GppAccessRegContext == nil {
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I think this condition is unnecessary because the UDM sent the dereg notification to the old AMF.

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

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@tim-ywliu tim-ywliu Sep 12, 2023 •
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if old context was existed, it should reply StatusOK with new request in body

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see #25 (comment)

header = make(http.Header)
udmUe, _ := udm_context.Getself().UdmUeFindBySupi(ueID)
header.Set("Location", udmUe.GetLocationURI(udm_context.LocationUriAmf3GppAccessRegistration))
return header, &registerRequest, nil
}
return nil, nil, nil
}

// TS 29.503 5.3.2.2.3
Expand Down