Nt AVPs
Nt (application id: 16777348)
The Nt interface enables communication between the Policy and Charging Rules Function (PCRF) and the Service Capability Exposure Function (SCEF). This interface facilitates the transfer of data transfer policies and is particularly relevant in IoT (Internet of Things) environments where efficient and regulated data communication is essential.
Nt interface workflow:
- Initiation by SCEF: The SCEF, typically based on a request from an external application or Service Capability Server (SCS), initiates a Background-Data-Transfer-Request (BTR) command to the PCRF. This request includes AVPs (Attribute-Value Pairs) such as Transfer-Request-Type, Application-Service-Provider-Identity, and various data volume parameters.
- Policy Retrieval by PCRF: Upon receiving the BTR command, the PCRF retrieves existing transfer policies related to the requesting Application Service Provider (ASP) from the Subscriber Profile Repository (SPR).
- Policy Evaluation and Response: The PCRF evaluates the retrieved policies based on the network's current state, including congestion levels and available resources. It then sends a Background-Data-Transfer-Answer (BTA) command back to the SCEF, containing the selected transfer policies.
- Policy Notification: If the BTA command includes multiple transfer policies, the SCEF selects the most appropriate one based on its criteria and sends a notification back to the PCRF. The SCEF then begins enforcing the selected policy.
- Policy Enforcement: The SCEF manages data transfers according to the established policies, ensuring that data from IoT devices is transmitted efficiently and in line with network conditions.
- Ongoing Policy Management: As network conditions or user requirements change, the PCRF can update the policies and communicate these updates to the SCEF through the Nt interface.
For complete technical specification of Nt interface in Diameter protocol please refer to: [3GPP TS 29.154]
package com.mobius.software.telco.protocols.diameter.primitives.nt
|
Name |
AVP Code |
Data Type |
Vendor |
|
Network-Area-Info-List |
4201 |
OctetString |
3GPP |
|
Provides network area information. It is encoded as specified in 3GPP [TS 29.274] within the Presence Reporting Area Action Information Element (IE), starting from octet 9. Encodes location information such as TAC (Tracking Area Code), E-UTRAN Cell IDs, and Service Area IDs. |
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|
Number-Of-UEs |
4209 |
Unsigned32 |
3GPP |
|
Used to specify the expected number of User Equipment (UE) in a particular network area or location. |
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|
Reference-Id |
4202 |
OctetString |
3GPP |
|
Used to provide a globally unique identifier assigned by the PCRF (Policy and Charging Rules Function). It correlates an SCS (Service Capability Server) or AS (Application Server) request with the transfer policy retrieved from the SPR (Subscriber Profile Repository). |
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|
Time-Window |
4204 |
Grouped |
3GPP |
|
Defines the time interval during which the SCS (Service Capability Server) or AS (Application Server) is allowed to perform background data transfers. It consists of two mandatory Date AVPs specifying the start and end times for the transfer window. The AVP structure is defined as follows: Transfer-Start-Time (Mandatory): Indicates the start time of the transfer window. Transfer-End-Time (Mandatory): Indicates the end time of the transfer window. Can include other AVPs relevant to the transfer context. |
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|
Transfer-End-Time |
4205 |
Time |
3GPP |
|
Specifies the NTP time (Network Time Protocol) at which the SCS (Service Capability Server) or AS (Application Server) must stop background data transfers. It ensures that transfers occur only within a predefined time window and facilitates time-bound policy enforcement. Must be included if Time-Window AVP is present. Must be later than or equal to Transfer-Start-Time AVP. |
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|
Transfer-Policy |
4207 |
Grouped |
3GPP |
|
Defines the policy rules governing data transfer between a Service Capability Server (SCS) or Application Server (AS) and the network. It is specified by the Policy and Charging Rules Function (PCRF) and can include restrictions like time windows, bandwidth limits, and rating groups. The AVP structure is defined as follows: Transfer-Policy-Id (Mandatory, Unsigned32): Identifies the specific transfer policy assigned to the session. Time-Window (Optional, Grouped): Specifies the valid time range for data transfers using Transfer-Start-Time and End-Time. Rating-Group (Optional, Unsigned32): Associates the transfer with a charging group for billing purposes. Max-Requested-Bandwidth-DL (Optional, Unsigned32): Sets the maximum allowed download bandwidth in bits per second. Max-Requested-Bandwidth-UL (Optional, Unsigned32): Sets the maximum allowed upload bandwidth in bits per second. |
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|
Transfer-Policy-Id |
4208 |
Unsigned32 |
3GPP |
|
Uniquely identifies a transfer policy associated with a specific Reference-Id in the Policy and Charging Rules Function (PCRF). It is used to correlate a data transfer policy with network rules defined by the PCRF. |
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|
Transfer-Request-Type |
4203 |
Enumerated |
3GPP |
|
Defines the reason for sending a Background Data Transfer (BT) request message. It specifies whether the request is for policy initiation or a policy notification procedure. Enumerated Values: 0 TRANSFER_POLICY_REQUEST: Sent to initiate a transfer policy request procedure. 1 TRANSFER_POLICY_NOTIFICATION: Sent to initiate a transfer policy notification procedure for updates. |
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|
Transfer-Start-Time |
4206 |
Time |
3GPP |
|
Specifies the Network Time Protocol (NTP) time when the Service Capability Server (SCS) or Application Server (AS) may start background data transfer. |
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