AMF-UE-NGAP-ID mismatch on NAS Authentication request and response

[Shashank6669]

Hello everyone,

An issue previously discovered in the srsRAN 4G 21.10 (previous discussion here) has been encountered again. The srsGNB appears to be truncating the AMF-UE-NGAP ID in the Authentication Response. This results in the AMF responding with an ErrorIndication message containing the error: radioNetwork: unknown-local-UE-NGAP-ID.

Here are some partial logs for this issue:

Authentication Request

NG Application Protocol (DownlinkNASTransport)
	NGAP-PDU: initiatingMessage (0)
		initiatingMessage
			procedureCode: id-DownlinkNASTransport (4)
			criticality: ignore (1)
			value
				DownlinkNASTransport
					protocolIEs: 3 items
						Item 0: id-AMF-UE-NGAP-ID
							ProtocolIE-Field
								id: id-AMF-UE-NGAP-ID (10)
								criticality: reject (0)
								value
									AMF-UE-NGAP-ID: 4294969659

Authentication Response

NG Application Protocol (UplinkNASTransport)
	NGAP-PDU: initiatingMessage (0)
		initiatingMessage
			procedureCode: id-UplinkNASTransport (46)
			criticality: ignore (1)
				value
					UplinkNASTransport
						protocolIEs: 4 items
							Item 0: id-AMF-UE-NGAP-ID
								ProtocolIE-Field
									id: id-AMF-UE-NGAP-ID (10)
									criticality: reject (0)
									value
AMF-UE-NGAP-ID: 2364

Error Indication

NG Application Protocol (ErrorIndication)
	NGAP-PDU: initiatingMessage (0)
		initiatingMessage
			procedureCode: id-ErrorIndication (9)
			criticality: ignore (1)
			value
				ErrorIndication
					protocolIEs: 3 items
						Item 0: id-AMF-UE-NGAP-ID
							ProtocolIE-Field
								id: id-AMF-UE-NGAP-ID (10)
								criticality: ignore (1)
								value
									AMF-UE-NGAP-ID: 2364
						Item 1: id-RAN-UE-NGAP-ID
							ProtocolIE-Field
								id: id-RAN-UE-NGAP-ID (85)
								criticality: ignore (1)
								value
									RAN-UE-NGAP-ID: 0
						Item 2: id-Cause
							ProtocolIE-Field
								id: id-Cause (15)
								criticality: ignore (1)
								value
								        Cause: radioNetwork (0)
                                                                                radioNetwork: unknown-local-UE-NGAP-ID (14)

srsRAN gNB changes the AMF-UE-NGAP-ID from 4294969659 in the authentication request to 2364 in the authentication response.

Is this a known issue in the current srsRAN gNB release?

[andrepuschmann]

Hey, the above mentioned issue should be fixed in main. Please retry and let us know. I am closing the ticket.