Downlink RIM Information Transfer

Message Fact Sheet

What is Downlink RIM Information Transfer in simple terms?

Downlink RIM Information Transfer is the NGAP message sent by the AMF to the NG-RAN node to deliver RAN Information Management data received from another RAN node.

Delivers RIM information from AMF to NG-RAN, supports indirect inter-RAN information exchange, carries source and destination context plus transparent RIM content, allows the receiving NG-RAN to process the RAN-specific payload, and separates RIM handling from normal RAN configuration update procedures.

Why this message matters

Downlink RIM Information Transfer is the AMF delivering RAN Information Management content down to NG-RAN after receiving or routing it through the core network.

Where this message appears in the call flow

RIM Information Transfer

Call flow position: AMF sends this non-UE-associated initiatingMessage when relayed RIM content must be delivered toward a target NG-RAN.

Typical state: Target NG-RAN receives the RIM Information Transfer payload and processes the RAN-specific content.

Preconditions:

• The AMF has received RIM information from a source RAN side.
• The target NG-RAN can be identified.
• The exchange is intended to use the NGAP core-network path.

Next likely message: Target NG-RAN processes the RIM payload

Indirect inter-RAN information exchange

Call flow position: The message is the AMF-to-NG-RAN delivery leg of an indirect RIM exchange.

Typical state: The AMF acts as the relay path, while the receiving NG-RAN interprets the transparent RIM payload.

Preconditions:

• Source and destination RAN context is available.
• The transparent RIM content is valid for the target NG-RAN.

Next likely message: RAN-side coordination continues

RIM versus configuration update distinction

Call flow position: Use this transfer-style procedure for RAN Information Management content, not for AMF-side configuration update signalling.

Typical state: Trace analysis separates Downlink RIM Information Transfer from AMF Configuration Update and Downlink RAN Configuration Transfer.

Preconditions:

• The payload belongs to a RIM information exchange context.
• The message carries RIM Information Transfer rather than SON Configuration Transfer or AMF configuration IEs.

Next likely message: Correct RIM delivery interpretation

Call flow position

Previous message(s): Uplink RIM Information Transfer, AMF received RIM information from a source NG-RAN, Target NG-RAN needs the RIM payload

Next message(s): Target NG-RAN processes the RIM information, RAN-side information management or coordination continues

Message direction and transport

Security context: Downlink RIM Information Transfer is non-UE-associated and carries relayed RAN information management content. Validate source and destination context, target NG-RAN selection, and transparent payload integrity before treating delivery as successful.

Message Structure Overview

• Downlink RIM Information Transfer is an AMF-to-NG-RAN non-UE-associated initiatingMessage.
• RIM Information Transfer is the key mandatory container.
• The container can carry source context, destination context, and transparent RIM information.
• The AMF forwards the content without interpreting every RAN-specific detail.
• The paired uplink path is Uplink RIM Information Transfer.

ASN.1 for Downlink RIM Information Transfer

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

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

How to read this ASN.1

Read this as a non-UE-associated NGAP envelope around a RIM Information Transfer container. NGAP delivers the relayed payload to NG-RAN, while the RIM payload remains RAN information management content.

Downlink RIM Information Transfer - Example Dump

NGAP-PDU
  initiatingMessage
    procedureCode: id-DownlinkRIMInformationTransfer
    criticality: ignore
    value: DownlinkRIMInformationTransfer
      protocolIEs:
        - id: id-RIMInformationTransfer
          value:
            sourceRANContext: <source RAN context>
            destinationRANContext: <destination RAN context>
            rimInformation: <transparent RIM information>

How to read this dump

• Treat this as a teaching example based on the expected message structure, not as a captured network trace.
• RIM Information Transfer is the main payload to inspect.
• Do not confuse this transfer container with SON Configuration Transfer used by Downlink RAN Configuration Transfer.

Important Information Elements

Detailed field explanation

What to check in logs and traces

• Confirm the direction is AMF to NG-RAN.
• Confirm the message is non-UE-associated.
• Check that RIM Information Transfer is present.
• Match it with Uplink RIM Information Transfer when forwarding is expected.
• Validate source and destination RAN context.
• Confirm the transparent RIM content is present and valid.
• Confirm the receiving NG-RAN processes the RIM payload.
• Confirm the trace is not being interpreted as Downlink RAN Configuration Transfer.

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.