| Protocol | e1ap | Network | 5g |
|---|---|---|---|
| Spec | 3GPP TS 37.483 | Spec Section | Bearer Context Modification successful outcome and related IE definitions (Release 18 baseline) |
| Direction | gNB-CU-UP -> gNB-CU-CP successfulOutcome | Message Type | UE-associated bearer-context modification confirmation |
| Full message name | 5G E1AP - Bearer Context Modification Response |
|---|---|
| Protocol | E1AP |
| Technology | 5G |
| Direction | gNB-CU-UP -> gNB-CU-CP successfulOutcome |
| Interface | E1 between gNB-CU-CP and gNB-CU-UP |
| Signaling bearer / channel | UE-associated E1AP signaling / SCTP carried E1AP successfulOutcome |
| Typical trigger | The CU-UP successfully processed Bearer Context Modification Request and can return the resulting bearer-context state. |
| Main purpose | Confirms that the CU-UP accepted bearer-context changes and reports the resulting bearer state the CU-CP should use going forward. |
| Main specification | 3GPP TS 37.483, Bearer Context Modification successful outcome and related IE definitions (Release 18 baseline) |
| Release added | Release 17 |
| Procedures where used | Bearer Context Modification, User-plane state update |
Bearer Context Modification Response is the E1AP successful outcome the gNB-CU-UP returns after accepting bearer-context changes for an existing UE.
Confirms that the CU-UP accepted bearer-context changes and reports the resulting bearer state the CU-CP should use going forward.
Bearer Context Modification Response is the CU-UP telling the CU-CP which bearer changes were successfully applied.
Call flow position: The CU-UP kept the modification procedure on the success path and returns the resulting bearer state.
Typical state: The bearer context remains active, but selected parts of it now reflect the requested change set.
Preconditions:
Next likely message: Later bearer-context control based on the confirmed modified state
Call flow position: The response reports the outcome of the requested bearer-context delta rather than creating a brand-new context.
Typical state: The CU-CP must compare old state, requested delta, and returned result.
Preconditions:
Next likely message: Further bearer-context maintenance if needed
Previous message(s): Bearer Context Modification Request
Next message(s): Bearer Context Modification Request, Bearer Context Release Command
Security context: Bearer Context Modification Response does not create NAS security. It reports the outcome of requested bearer-state changes at the CU-UP.
BearerContextModificationResponse ::= SEQUENCE {
protocolIEs ProtocolIE-Container { {BearerContextModificationResponse-IEs} },
...
}
BearerContextModificationResponse-IEs E1AP-PROTOCOL-IES ::= {
{ gNB-CU-CP UE E1AP ID, mandatory } |
{ gNB-CU-UP UE E1AP ID, mandatory } |
{ System Bearer Context Modification Response, mandatory } |
{ Criticality Diagnostics, optional },
...
}
Read the response as the CU-UP's returned delta result. Its value comes from showing what changed successfully in the active bearer context.
E1AP-PDU
successfulOutcome
procedureCode: id-bearerContextModification
criticality: reject
value: BearerContextModificationResponse
protocolIEs:
- id: id-gNB-CU-CP-UE-E1AP-ID
value: 0x00004192
- id: id-gNB-CU-UP-UE-E1AP-ID
value: 0x00000087
- id: id-System-BearerContextModificationResponse
value:
pdu-session-list:
- pdu-session-id: 10
drb-modified-list:
- drb-id: 4
| IE | Required | Description |
|---|---|---|
gNB-CU-CP UE E1AP ID | Yes | Mandatory CU-CP side UE identifier used to correlate the response with the original modification request. |
gNB-CU-UP UE E1AP ID | Yes | Mandatory CU-UP side UE identifier for the modified bearer context. |
System Bearer Context Modification Response | Yes | Mandatory bearer result payload reporting the resulting modified bearer state. |
Criticality Diagnostics | Optional | Optional diagnostics if the CU-UP needs to report additional protocol handling detail. |
gNB-CU-CP UE E1AP IDMandatory CU-CP side UE identifier used to correlate the response with the original modification request.
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 modified bearer context.
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.
System Bearer Context Modification ResponseMandatory bearer result payload reporting the resulting modified bearer state.
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.
Criticality DiagnosticsOptional diagnostics if the CU-UP needs to report additional protocol handling detail.
Presence: Optional
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: The returned modified state may not match the requested delta or later logic may still be assuming the old state.
What to inspect: Compare the response payload with both the old bearer state and the requested delta.
Next step: Use the response as the CU-UP truth for what the bearer became after modification.
The request asks for a bearer-state delta. The response reports the delta outcome the CU-UP actually applied.
It is the E1AP successful outcome the CU-UP sends after bearer-context modification succeeds.
The key fields are the two UE E1AP identifiers and the returned system bearer context modification result.
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.