What is ESM Data Transport in LTE?
It is the ESM message used to carry small IP, non-IP, or Ethernet data through the control plane.
| Protocol | nas | Network | lte |
|---|---|---|---|
| Spec | 3GPP TS 24.301 | Spec Section | 6.6.1, 8.3.25 |
| Direction | UE to MME | Message Type | ESM signaling |
| Full message name | LTE ESM Data Transport |
|---|---|
| Protocol | NAS |
| Technology | LTE |
| Direction | UE to MME |
| Interface | N1 over LTE access / S1-MME control path |
| Signaling bearer / channel | NAS signaling / Commonly carried inside Control Plane Service Request or sent during control-plane CIoT small-data handling. |
| Typical trigger | Triggered when small data should use control-plane CIoT EPS optimization instead of normal user-plane bearer setup. |
| Main purpose | Carries small IP, non-IP, or Ethernet data in the NAS layer so the UE can exchange limited user data without first setting up the normal user-plane path. |
| Main specification | 3GPP TS 24.301, 6.6.1, 8.3.25 |
| Release added | Release 13 |
| Procedures where used | Control Plane CIoT EPS Optimization, ESM Data Transport Procedure |
| Related timers | T3346, T3447 |
ESM Data Transport is the LTE NAS message used to carry small user data through the control plane when control-plane CIoT EPS optimization is in use.
Carries small IP, non-IP, or Ethernet data in the NAS layer so the UE can exchange limited user data without first setting up the normal user-plane path.
ESM Data Transport is the LTE NAS message used to move small user data through the control plane.
Call flow position: UE-originated small-data transport carried inside the control-plane CIoT service branch.
Typical state: The UE is sending data through NAS rather than through a normal user-plane bearer.
Preconditions:
Next likely message: Downlink NAS Transport or later service completion
Call flow position: UE-originated small-data continuation after a paging-triggered control-plane restore.
Typical state: The UE is already back in contact with the network and is moving user data through the control plane.
Preconditions:
Next likely message: Downlink NAS Transport or service completion
Previous message(s): Control Plane Service Request, Service Accept
Next message(s): Downlink NAS Transport, Service Accept
Security context: Protected by the active NAS security context because it carries data through NAS signaling.
ESM Data Transport
User data container
Release assistance indication OPTIONAL
Read the message from the control-plane service context first and then inspect the data-carrying branch.
ESM Data Transport
Protocol discriminator: EPS session management
EPS bearer identity: 0
Procedure transaction identity: 11
Message type: ESM Data Transport
User data container: small IP payload
Release assistance indication: release preferred
| IE | Required | Description |
|---|---|---|
User data container | Yes | Carries the small IP, non-IP, or Ethernet payload being sent through the control plane. |
Release assistance indication | Optional | May tell the network that the NAS signaling connection can be released after data delivery. |
User data containerCarries the small IP, non-IP, or Ethernet payload being sent through the control plane.
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.
Release assistance indicationMay tell the network that the NAS signaling connection can be released after data delivery.
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 trace may be using ESM Data Transport over the control plane.
What to inspect: Check Control Plane Service Request, ESM Data Transport, and any later Downlink NAS Transport.
Next step: Treat the path as intentional control-plane data transfer before blaming missing user-plane setup.
It is the ESM message used to carry small IP, non-IP, or Ethernet data through the control plane.
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.