What is Bearer Resource Modification Request in LTE?
It is the UE message that asks the network to change an already active bearer resource.
| Protocol | nas | Network | lte |
|---|---|---|---|
| Spec | 3GPP TS 24.301 | Spec Section | 6.5.4, 8.3.10 |
| Direction | UE to MME | Message Type | ESM signaling |
| Full message name | LTE Bearer Resource Modification Request |
|---|---|
| Protocol | NAS |
| Technology | LTE |
| Direction | UE to MME |
| Interface | N1 over LTE access / S1-MME control path |
| Signaling bearer / channel | NAS signaling / Sent after a dedicated bearer resource already exists and the UE wants to update it. |
| Typical trigger | Triggered when the UE needs to change QoS or traffic-flow parameters of an existing dedicated bearer resource. |
| Main purpose | Requests modification of a bearer resource that already exists so the network can adjust QoS or traffic-flow handling without creating a fresh bearer. |
| Main specification | 3GPP TS 24.301, 6.5.4, 8.3.10 |
| Release added | Release 8 |
| Procedures where used | Bearer Resource Modification Procedure |
| Related timers | T3480 |
| Related cause values | ESM cause |
Bearer Resource Modification Request is the LTE NAS message the UE sends when it wants to change QoS or traffic-flow settings for an existing dedicated bearer resource.
Requests modification of a bearer resource that already exists so the network can adjust QoS or traffic-flow handling without creating a fresh bearer.
Bearer Resource Modification Request is the UE asking to change a dedicated bearer resource that already exists.
Call flow position: UE-originated bearer-modification request used when an active dedicated bearer needs new QoS.
Typical state: The bearer already exists and the UE wants the network to adjust its definition.
Preconditions:
Next likely message: Modify EPS Bearer Context Request or Bearer Resource Modification Reject
Call flow position: UE-originated bearer-modification request used when the traffic-flow handling on an active bearer should change.
Typical state: The bearer stays active while the UE asks for a changed live definition.
Preconditions:
Next likely message: Modify EPS Bearer Context Request or Bearer Resource Modification Reject
Previous message(s): Activate Dedicated EPS Bearer Context Accept
Next message(s): Modify EPS Bearer Context Request
Security context: Protected by the active NAS security context because it changes live bearer state.
Bearer Resource Modification Request
Linked EPS bearer identity
Traffic flow aggregate
Required traffic flow QoS OPTIONAL
ESM cause OPTIONAL
Protocol configuration options OPTIONAL
Device properties OPTIONAL
NBIFOM container OPTIONAL
Header compression configuration OPTIONAL
Extended protocol configuration options OPTIONAL
Read the linked bearer identity and traffic-flow aggregate first, then inspect what live parameter the UE wants to change.
Bearer Resource Modification Request
Protocol discriminator: EPS session management
EPS bearer identity: 0
Procedure transaction identity: 10
Message type: Bearer Resource Modification Request
Linked EPS bearer identity: 5
Traffic flow aggregate: IMS voice media
Required traffic flow QoS: QCI 1
| IE | Required | Description |
|---|---|---|
Linked EPS bearer identity | Yes | Identifies the default bearer and PDN connection the modified resource belongs to. |
Traffic flow aggregate | Yes | Describes the traffic flow that should use the modified resource definition. |
Required traffic flow QoS | Optional | Shows the new QoS the UE is requesting for the modified resource. |
ESM cause | Optional | May explain why the bearer resource should be changed from the UE side. |
Linked EPS bearer identityIdentifies the default bearer and PDN connection the modified resource belongs to.
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.
Traffic flow aggregateDescribes the traffic flow that should use the modified resource definition.
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.
Required traffic flow QoSShows the new QoS the UE is requesting for the modified resource.
Presence: Optional
In practice: QoS rules are the real service profile of the session. Inspect the QFI mapping, packet filters, and precedence because those values explain how user traffic will actually be classified and forwarded.
ESM causeMay explain why the bearer resource should be changed from the UE side.
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 bearer-modification branch may have stalled or been rejected.
What to inspect: Check Bearer Resource Modification Request and the next ESM branch.
Next step: Treat the issue as a modification problem on an existing bearer, not as a fresh bearer setup failure.
It is the UE message that asks the network to change an already active bearer resource.
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.