| Protocol | e1ap | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 37.483 | Spec Section | Bearer Context Release Request procedure and related IE definitions (Release 18 baseline) |
| Direction | gNB-CU-UP -> gNB-CU-CP initiatingMessage | Message Type | UE-associated CU-UP initiated bearer release request |
| Full message name | 5G E1AP - Bearer Context Release Request |
|---|---|
| Protocol | E1AP |
| Technology | 5G |
| Direction | gNB-CU-UP -> gNB-CU-CP initiatingMessage |
| Interface | E1 between gNB-CU-CP and gNB-CU-UP |
| Signaling bearer / channel | UE-associated E1AP signaling / SCTP carried E1AP initiatingMessage |
| Typical trigger | The CU-UP determines that the current bearer branch should be released and needs the CU-CP to drive the control-plane release handling. |
| Main purpose | Tells the CU-CP that the CU-UP requires control-plane action to release the current bearer branch for a UE. |
| Main specification | 3GPP TS 37.483, Bearer Context Release Request procedure and related IE definitions (Release 18 baseline) |
| Release added | Release 17 |
| Procedures where used | CU-UP initiated bearer release, Bearer teardown escalation, Release-side control-plane follow-up |
Bearer Context Release Request is the E1AP message the gNB-CU-UP sends to the gNB-CU-CP when the CU-UP needs the control plane to handle release of an existing bearer context.
Tells the CU-CP that the CU-UP requires control-plane action to release the current bearer branch for a UE.
Bearer Context Release Request is the CU-UP asking the CU-CP to start release handling for a bearer branch.
Call flow position: The CU-UP asks the CU-CP to take release-side control-plane action for an active bearer branch.
Typical state: The bearer branch still exists, but the CU-UP is signaling that it should be released.
Preconditions:
Next likely message: Bearer Context Release Command or another release-side control-plane continuation
Call flow position: The request exposes why the CU-UP wants the bearer branch torn down.
Typical state: The CU-CP must interpret the reason and decide how to proceed with release handling.
Preconditions:
Next likely message: Release-side control-plane action based on the reported reason
Previous message(s): Bearer Context Setup Response, Bearer Context Modification Response
Next message(s): Bearer Context Release Command, Bearer Context Release Complete
Security context: Bearer Context Release Request does not create security context. It escalates a bearer-release need from the CU-UP to the CU-CP.
BearerContextReleaseRequest ::= SEQUENCE {
protocolIEs ProtocolIE-Container { {BearerContextReleaseRequest-IEs} },
...
}
BearerContextReleaseRequest-IEs E1AP-PROTOCOL-IES ::= {
{ gNB-CU-CP UE E1AP ID, mandatory } |
{ gNB-CU-UP UE E1AP ID, mandatory } |
{ Cause, mandatory },
...
}
Release Request is operationally important because the CU-UP becomes the initiator of a release-side control-plane action.
E1AP-PDU
initiatingMessage
procedureCode: id-bearerContextReleaseRequest
criticality: reject
value: BearerContextReleaseRequest
protocolIEs:
- id: id-gNB-CU-CP-UE-E1AP-ID
value: 0x00004192
- id: id-gNB-CU-UP-UE-E1AP-ID
value: 0x00000087
- id: id-Cause
value:
radioNetwork: unspecified
| IE | Required | Description |
|---|---|---|
gNB-CU-CP UE E1AP ID | Yes | Mandatory CU-CP side UE identifier used so the control plane can correlate the release request with the right bearer branch. |
gNB-CU-UP UE E1AP ID | Yes | Mandatory CU-UP side UE identifier for the bearer context the CU-UP wants released. |
Cause | Yes | Mandatory reason explaining why the CU-UP is requesting control-plane driven release handling. |
gNB-CU-CP UE E1AP IDMandatory CU-CP side UE identifier used so the control plane can correlate the release request with the right bearer branch.
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.
gNB-CU-UP UE E1AP IDMandatory CU-UP side UE identifier for the bearer context the CU-UP wants released.
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.
CauseMandatory reason explaining why the CU-UP is requesting control-plane driven release handling.
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.
Likely cause: Bearer Context Release Request may be missing, mis-correlated, or not being handled as the release trigger.
What to inspect: Read Bearer Context Release Request and correlate Cause with the later release-side control-plane actions.
Next step: Drive the release sequence from the CU-UP initiated request before interpreting later command or completion messages.
Release Request is CU-UP initiated and asks the CU-CP to take release action. Release Command is CU-CP initiated and orders the CU-UP to perform release.
It is the E1AP message the CU-UP sends when it needs the CU-CP to handle release of an existing bearer branch.
It is important because it shows that the release path was initiated from the CU-UP side rather than from the CU-CP side.
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.