RRC 5G gNB -> UE 3GPP TS 38.331

5G NR - RRC Reestablishment

RRC Reestablishment is the downlink NR RRC message the network sends when it accepts a reestablishment attempt and provides the recovered connected-mode context.

Message Fact Sheet

Protocol	rrc	Network	5g
Spec	3GPP TS 38.331	Spec Section	5.3.7, 6.2.2
Direction	gNB -> UE	Message Type	Connection Recovery

Full message name	5G NR - RRC Reestablishment
Protocol	RRC
Technology	5G
Direction	gNB -> UE
Interface	Uu
Signaling bearer / channel	SRB1 / DL-DCCH
Typical trigger	Sent when the gNB accepts an RRC Reestablishment Request and continues with recovery.
Main purpose	Lets the UE resume protected connected-mode signaling after radio link failure recovery while reusing the recovered context.
Main specification	3GPP TS 38.331, 5.3.7, 6.2.2
Release added	Release 15
Procedures where used	RRC Reestablishment, Radio Link Failure Recovery
Related timers	T301
Related cause values	None highlighted

What is RRC Reestablishment in simple terms?

RRC Reestablishment is the downlink NR RRC message the network sends when it accepts a reestablishment attempt and provides the recovered connected-mode context.

Lets the UE resume protected connected-mode signaling after radio link failure recovery while reusing the recovered context.

Why this message matters

RRC Reestablishment is the network's acceptance message for RLF recovery.

Where this message appears in the call flow

RRC Reestablishment

Call flow position: Sent after the network accepts the UE's reestablishment request.

Typical state: UE is recovering from radio link failure.

Preconditions:

The UE sent a valid RRC Reestablishment Request.

Next likely message: RRC Reestablishment Complete

Call flow position

Previous message(s): RRC Reestablishment Request

Next message(s): RRC Reestablishment Complete

Message direction and transport

Sender and receiver: gNB -> UE

Interface: Uu

Domain: Access-side radio control and recovery

Signaling bearer: SRB1

Logical channel: DL-DCCH

Transport / encapsulation: Dedicated RRC signaling after a successful reestablishment attempt

Security context: Part of the reestablishment recovery path and tied to recovered security context.

Message Structure Overview

The message restores the UE's connected context rather than creating a brand-new setup path.

ASN.1 for 5G NR - RRC Reestablishment

RRCReestablishment ::= SEQUENCE {
  criticalExtensions CHOICE {
    rrcReestablishment RRCReestablishment-IEs,
    ...
  }
}

How to read this ASN.1

The practical checks are whether the reestablishment was accepted and what recovered configuration was sent back.

Decoded Message Dump

DL-DCCH-Message
  message: rrcReestablishment
    radioBearerConfig: present

How to read this dump

If this message exists, the network accepted the recovery path.

Important Information Elements

IE	Required	Description
`radioBearerConfig`	Yes	Recovered configuration the UE uses to rebuild the connected radio context.
`nextHopChainingCount`	Optional	Security-related count used during recovery handling.

Detailed field explanation

`radioBearerConfig`

Recovered configuration the UE uses to rebuild the connected radio context.

Presence: Required

`nextHopChainingCount`

Security-related count used during recovery handling.

Presence: Optional

What to check in logs and traces

Check the UE's earlier Reestablishment Request.
Confirm the recovered bearer and security context are consistent.

Common Issues and Troubleshooting

The UE starts reestablishment but still fails to recover.

Likely cause: The recovered context may be incomplete or inconsistent.

What to inspect: Check the reestablishment payload and the later complete message.

Next step: Correlate with the radio failure cause and follow-on RRC messages.

Detailed explanation

5G NR - RRC Reestablishment Explained

RRC Reestablishment is a 5G NR RRC message reference page for engineers who need to understand what the message carries, where it fits in the procedure, and what to inspect in traces when behavior does not match expectation.

RRC Reestablishment is the downlink NR RRC message the network sends when it accepts a reestablishment attempt and provides the recovered connected-mode context. Lets the UE resume protected connected-mode signaling after radio link failure recovery while reusing the recovered context.

What is RRC Reestablishment in simple terms?

RRC Reestablishment is the downlink NR RRC message the network sends to the UE when this specific procedure step needs to be controlled, configured, or completed.

Lets the UE resume protected connected-mode signaling after radio link failure recovery while reusing the recovered context.

Why this message matters

it directly affects RRC Reestablishment, Radio Link Failure Recovery
The UE starts reestablishment but still fails to recover
Sent when the gNB accepts an RRC Reestablishment Request and continues with recovery

Where this message appears in the call flow

RRC Reestablishment is typically seen during RRC Reestablishment. Engineers usually read it together with the messages just before and just after it so they can tell whether the procedure is progressing normally or drifting into a fallback or failure path.

The UE is usually in recovering from radio link failure when engineers evaluate this message in traces. In the main procedure context, it appears sent after the network accepts the UE’s reestablishment request. Before this message appears, the important preconditions are The UE sent a valid RRC Reestablishment Request..

Simplified sequence:

UE                       gNB / Network
|                        |
|--- RRC Reestablishment Request ----------->|
|<-- RRC Reestablishment -----------|
|--- RRC Reestablishment Complete ----------->|

Message direction and transport

sender: gNB
receiver: UE
interface: Uu
signaling bearer: SRB1
signaling channel: DL-DCCH
transport type: Dedicated RRC signaling after a successful reestablishment attempt
domain: Access-side radio control and recovery
security context: Part of the reestablishment recovery path and tied to recovered security context.

Important Information Elements

IE	Why it matters
`radioBearerConfig`	Recovered configuration the UE uses to rebuild the connected radio context.
`nextHopChainingCount`	Security-related count used during recovery handling.

Example message dump

DL-DCCH-Message
  message: rrcReestablishment
    radioBearerConfig: present

How to read this dump

If this message exists, the network accepted the recovery path.

FAQ

What happens after RRC Reestablishment?

The UE normally answers with RRC Reestablishment Complete if recovery succeeds.

Summary

RRC Reestablishment is the downlink NR RRC message the network sends when it accepts a reestablishment attempt and provides the recovered connected-mode context.

Advanced Engineer Notes

This is different from fresh RRC Setup because it tries to recover an existing context.

Related message pages

Related Procedures

5G RRC Reestablishment

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.