Uplink RAN Configuration Transfer

Message Fact Sheet

What is Uplink RAN Configuration Transfer in simple terms?

Uplink RAN Configuration Transfer is the NGAP message sent by the NG-RAN node to the AMF to transfer RAN configuration information toward another RAN node through the core network.

Transfers RAN configuration information from NG-RAN to AMF, supports indirect RAN-to-RAN configuration exchange, helps coordinate RAN nodes through the core network, carries source and target identity plus transfer container information, and separates RAN configuration transfer from normal NGAP configuration update messages.

Why this message matters

Uplink RAN Configuration Transfer is the NG-RAN sending a RAN-to-RAN configuration transfer container up to the AMF so the core network can relay it toward the destination RAN side.

Where this message appears in the call flow

RAN Configuration Transfer

Call flow position: NG-RAN sends this non-UE-associated initiatingMessage when RAN configuration transfer content must be relayed toward another RAN node through the AMF.

Typical state: AMF receives the SON Configuration Transfer container and can forward it using Downlink RAN Configuration Transfer where applicable.

Preconditions:

• The NG-RAN has RAN configuration information to transfer.
• The destination RAN node or RAN-side entity can be identified.
• The transfer is intended to use the core-network path rather than a direct inter-RAN interface.

Next likely message: Downlink RAN Configuration Transfer

Indirect RAN-to-RAN coordination

Call flow position: The message provides an AMF-relayed path for coordination content between RAN nodes.

Typical state: The AMF acts as the control-plane relay for the transfer container without treating it as a local RAN Configuration Update.

Preconditions:

• Source and target RAN context is available.
• The transfer content is valid for the receiving RAN side.

Next likely message: Receiving RAN node processes the transparent container

Transfer versus update distinction

Call flow position: Use this transport-style procedure when configuration content is meant for another RAN-side entity, not when the reporting NG-RAN updates AMF-side knowledge of itself.

Typical state: Trace analysis separates RAN Configuration Transfer from RAN Configuration Update.

Preconditions:

• The payload belongs to a RAN-to-RAN transfer context.
• The message is non-UE-associated and carries SON Configuration Transfer.

Next likely message: Correct RAN configuration transfer interpretation

Call flow position

Previous message(s): NG-RAN has a configuration transfer container ready, Destination RAN-side entity needs the container, Direct inter-RAN transfer is unavailable or not used

Next message(s): AMF receives SON Configuration Transfer, Downlink RAN Configuration Transfer

Message direction and transport

Security context: Uplink RAN Configuration Transfer is non-UE-associated and carries RAN-side configuration transfer content. Validate source, target, and transparent container handling before treating the transfer as successfully relayed.

Message Structure Overview

• Uplink RAN Configuration Transfer is an NG-RAN-to-AMF non-UE-associated initiatingMessage.
• SON Configuration Transfer is the key mandatory container.
• The container can carry source RAN node identity, target RAN node identity, and transparent RAN configuration information.
• The AMF provides the core-network relay path and does not need to interpret every RAN-specific detail in the transparent content.
• The paired downlink path is Downlink RAN Configuration Transfer.

ASN.1 for Uplink RAN Configuration Transfer

UplinkRANConfigurationTransfer ::= SEQUENCE {
  protocolIEs ProtocolIE-Container { {UplinkRANConfigurationTransfer-IEs} },
  ...
}

UplinkRANConfigurationTransfer-IEs NGAP-PROTOCOL-IES ::= {
  { ID id-SONConfigurationTransfer  CRITICALITY ignore  TYPE SONConfigurationTransfer  PRESENCE mandatory },
  ...
}

How to read this ASN.1

Read this as a non-UE-associated NGAP envelope around a SON Configuration Transfer container. The AMF uses the NGAP procedure to relay RAN configuration transfer content rather than to update its own stored configuration for the sending NG-RAN.

Uplink RAN Configuration Transfer - Example Dump

NGAP-PDU
  initiatingMessage
    procedureCode: id-UplinkRANConfigurationTransfer
    criticality: ignore
    value: UplinkRANConfigurationTransfer
      protocolIEs:
        - id: id-SONConfigurationTransfer
          value:
            sourceRANNodeID: <source RAN node identity>
            targetRANNodeID: <target RAN node identity>
            sONInformation: <transparent RAN configuration transfer information>

How to read this dump

• Treat this as a teaching example based on the expected message structure, not as a captured network trace.
• SON Configuration Transfer is the main payload to inspect.
• Do not confuse this transfer container with RAN Configuration Update, which refreshes AMF-side knowledge of the reporting NG-RAN.

Important Information Elements

Detailed field explanation

What to check in logs and traces

• Confirm the direction is NG-RAN to AMF.
• Check that SON Configuration Transfer is present.
• Validate source and target RAN identities.
• Confirm the transparent transfer container is not empty or malformed.
• Look for Downlink RAN Configuration Transfer when AMF forwarding is expected.
• Confirm the trace is not being interpreted as RAN Configuration Update.
• Use an analyzer profile that can display or export the transparent RAN configuration transfer content.

Common Issues and Troubleshooting

LTE / 5G / Variant Comparison

FAQ

Related message pages

Related Procedures

Related Tools

• 3GPP Decoder
• NR ARFCN Calculator
• NR GSCN Calculator

Use This Reference in Practice

Decode this message with the 3GPP Decoder, inspect the related message database, or open the matching call flow to see where this signaling step fits in the full procedure.