What is SN id Serving Network Identifier

Demystifying SN id: The Identity Badge of a Serving Network

Within the realm of mobile telecommunications, particularly 5G networks, the Serving Network Identifier (SN id) emerges as a critical piece of information used for user equipment (UE) authentication and network identification. Let's delve into the technical details of SN id, exploring its role and significance in the 5G core network architecture.

Understanding Network Identification in Cellular Systems:

When a UE (mobile device) connects to a cellular network, it needs to establish its location and identify the network it's currently attached to. This identification process plays a crucial role in:

  • Routing Calls and Data: The network needs to know where the UE is located to properly route incoming calls, messages, and data traffic.
  • Security Procedures: Authentication and authorization procedures rely on identifying the serving network to ensure secure communication.

Traditional Cell Global Identity (CGI):

In older cellular network generations (2G, 3G, 4G), a parameter called Cell Global Identity (CGI) served the purpose of network identification. The CGI encompasses a combination of:

  • Mobile Country Code (MCC): A unique identifier for the country where the network operates.
  • Mobile Network Code (MNC): A unique identifier for the specific mobile network operator within the country.
  • Location Area Code (LAC): A code identifying a broader geographical area within the network.
  • Cell ID: A unique identifier for a specific cell site within the network.

The Rise of 5G and the Introduction of SN id:

The 5G core network architecture departs from the traditional approach used in earlier generations. It introduces a more streamlined and centralized method for network identification using the SN id. This shift is driven by factors like:

  • Network Slicing: 5G networks can be logically divided into slices, catering to diverse service requirements. SN id helps identify the specific network slice a UE is connected to.
  • Separation of Control and User Planes: The 5G core separates control plane functions (managing how data is routed) from the user plane (carrying the actual user data). SN id plays a role in both planes for identification purposes.

Composition of the SN id:

The SN id in 5G primarily consists of two parts:

  1. S N Network Identifier (SNN-ID): This identifier is typically defined in the 3GPP (3rd Generation Partnership Project) technical specifications (TS 24.501). It usually corresponds to the MCC and MNC combination used in the traditional CGI approach.
  2. Service Code (Optional): For certain network slicing scenarios, an additional service code might be appended to the SNN-ID within the SN id. This code helps distinguish between different network slices offered by the same mobile network operator.

The Role of SN id in 5G Core Network Procedures:

SN id plays a vital role in several 5G core network procedures:

  • UE Registration: When a UE connects to the network, it transmits its identity information along with the SN id. This helps the network identify the UE's home network and attach it to the appropriate serving network slice.
  • Authentication and Key Derivation: The SN id is used during authentication procedures to verify the UE's legitimacy and derive cryptographic keys for secure communication.
  • Signaling and Routing: The SN id is used within signaling messages exchanged between network functions for routing purposes, ensuring data reaches the intended UE.

Benefits of Utilizing SN id:

Compared to the traditional CGI approach, SN id offers several advantages:

  • Efficiency: SN id provides a more concise and centralized method for network identification within the 5G core network architecture.
  • Flexibility: The inclusion of an optional service code within SN id facilitates the management of network slicing scenarios.
  • Scalability: SN id is well-suited for the evolving needs of 5G networks, with the potential to accommodate future network functionalities.

Conclusion:

The Serving Network Identifier (SN id) serves as a cornerstone for network identification within the 5G core network. By understanding its composition, role in various procedures, and benefits over traditional methods, we gain valuable insight into the technical underpinnings of mobile network operation in the 5G era.