RRC 5G IAB node / UE -> donor / gNB 3GPP TS 38.331

5G NR - Indirect Path Failure Information

Indirect Path Failure Information is an NR RRC message used to report failure related to an indirect path or relayed path in advanced deployment scenarios.

Message Fact Sheet

Protocol	rrc	Network	5g
Spec	3GPP TS 38.331	Spec Section	6.2.2
Direction	IAB node / UE -> donor / gNB	Message Type	Failure Reporting

Full message name	5G NR - Indirect Path Failure Information
Protocol	RRC
Technology	5G
Direction	IAB node / UE -> donor / gNB
Interface	Uu / IAB radio path
Signaling bearer / channel	SRB1 / SRB2 / UL-DCCH
Typical trigger	Used when an indirect path or relayed path failure must be reported upward.
Main purpose	Lets the reporting node inform the controlling network side that an indirect transport or relay-related path has failed.
Main specification	3GPP TS 38.331, 6.2.2
Release added	Release 16
Procedures where used	Relay / IAB Failure Reporting, Indirect Path Recovery

What is Indirect Path Failure Information in simple terms?

Indirect Path Failure Information is an NR RRC message used to report failure related to an indirect path or relayed path in advanced deployment scenarios.

Lets the reporting node inform the controlling network side that an indirect transport or relay-related path has failed.

Why this message matters

This message reports that an indirect or relayed path has failed.

Where this message appears in the call flow

IAB / Relay Failure Reporting

Call flow position: Sent when an indirect path fails and the controlling node must be informed.

Typical state: Node is in connected operation with an active indirect path.

Preconditions:

An indirect path exists and later fails.

Next likely message: Recovery, reconfiguration, or release handling

Call flow position

Previous message(s): RRC Reconfiguration

Next message(s): Recovery handling, Later reconfiguration or release

Message direction and transport

Sender and receiver: IAB node / UE -> donor / gNB

Interface: Uu / IAB radio path

Domain: Access-side failure reporting

Signaling bearer: SRB1 / SRB2

Logical channel: UL-DCCH

Transport / encapsulation: Dedicated RRC signaling in advanced relay or IAB context

Security context: Protected connected-mode signaling.

Message Structure Overview

The important question is what path failed and how the network reacts after the report.

ASN.1 for 5G NR - Indirect Path Failure Information

IndirectPathFailureInformation ::= SEQUENCE {
  failureInfo OCTET STRING
}

How to read this ASN.1

The wrapper is small; the real troubleshooting value is in the failure context and the following recovery action.

5G NR - Indirect Path Failure Information - Example Dump

UL-DCCH-Message
  message: indirectPathFailureInformation
    failureInfo: present

How to read this dump

Correlate the report with the exact path or relay problem seen at lower layers.

Important Information Elements

IE	Required	Description
`failureInfo`	Yes	Carries the information needed to identify and interpret the indirect path failure.

Detailed field explanation

`failureInfo`

Carries the information needed to identify and interpret the indirect path failure.

Presence: Required

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

What to check in logs and traces

Check what indirect path was active before the failure.
Correlate this report with later recovery or release signaling.

Common Issues and Troubleshooting

Traffic on a relayed or indirect path stops unexpectedly.

Likely cause: The indirect path failed and was reported through this message.

What to inspect: Check the failure information and correlate it with IAB or relay-layer logs.

Next step: Follow the later recovery or reconfiguration sequence.

FAQ

What is Indirect Path Failure Information used for?

It is used to report that an indirect or relayed path has failed.

Related message pages

Related Procedures

5G RRC Reconfiguration

Related Tools

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.