The S13 interface in LTE networks is a reference point that connects the Mobility Management Entity (MME) with the Equipment Identity Register (EIR). This interface enables the MME to verify the identity of mobile equipment, ensuring that it is neither blacklisted nor faulty.
LTE S13 Interface.
The primary function of the S13 interface is to facilitate the Identity Check procedure, which is integral to the user equipment (UE) attach process. This procedure involves sending an ME-Identity-Check Request (ECR) message from the MME to the EIR, and receiving an ME-Identity-Check Answer (ECA) message in response. This interaction confirms the validity of the mobile equipment.
The S13 interface relies on the Diameter protocol for communication, with messages transported over the Stream Control Transmission Protocol (SCTP). SCTP ensures the reliable delivery of Diameter messages between the MME and the EIR. To enhance reliability and fault tolerance, the S13 interface supports both single-homing and multi-homing configurations. Single-homing utilizes a single communication path, while multi-homing employs multiple paths, thereby improving the robustness of the connection.
The EIR plays a pivotal role in this setup by verifying the ME identity against its database to determine if the equipment is blacklisted or has known faults. The MME analyzes the response from the EIR to decide the appropriate course of action, such as accepting or rejecting the attach request based on the status of the mobile equipment.
This verification process is essential for maintaining network security, preventing the use of stolen devices, and ensuring that faulty equipment does not disrupt network operations.
In scenarios where the EIR is co-located with the Home Subscriber Server (HSS), the S13 interface operates over the S6a interface. This integration streamlines the identity check process within the network infrastructure.
The ME Identity Check procedure is not only crucial for security purposes but also allows network operators to exercise control over their network by rejecting attach requests from blacklisted devices. This ensures that only verified and reliable mobile equipment can access the network, thereby enhancing overall network integrity and user experience.