What is CUPS?

What is CUPS?

1. CUPS (Control and User Plane Separation): CUPS is a concept used in modern networking architectures, particularly in mobile networks like 4G and 5G. It involves separating the control plane and user plane functionalities of network elements, such as gateways. The control plane handles signaling and control-related functions, while the user plane deals with actual data transmission.
2. Functional Entities and Divisions: In the context of CUPS, the gateway (which could be either the Serving Gateway - S-GW or the Packet Data Network Gateway - P-GW) is divided into different functional entities, each responsible for specific tasks.

• SGW-C and SGW-U: The Serving Gateway (SGW) has two divisions - SGW-C and SGW-U.
• SGW-C (Control Plane of SGW): This is responsible for control-related functions like handling signaling between various network elements, managing the mobility of devices, and handling policy enforcement.
• SGW-U (User Plane of SGW): This is responsible for forwarding data routing user data between the device and the external network.
• PGW-C and PGW-U: Similarly, for the Packet Data Network Gateway (PGW), the divisions are PGW-C and PGW-U.
• PGW-C (Control Plane of PGW): This manages control-related tasks like IP address allocation, quality of service (QoS) enforcement, and charging information.
• PGW-U (User Plane of PGW): This handles the forwarding of user data between the device and external networks.

1. CloudEdge Architecture: The passage also mentions "CloudEdge," which appears to be a specific architecture or framework. In this architecture:

• Control-Plane Gateway (CGW): This gateway provides control-plane functions, which handles signaling and control-related tasks. It seems to offer both SGW-C and/or PGW-C functions, depending on the network's requirements.
• User-Plane Gateway (DGW): This gateway provides user-plane functions, dealing with actual data transmission. Depending on the network's needs, it offers SGW-U and/or PGW-U functions

Interfaces:

?Sxa: SGW-C <-> SGW-U, R14 29.244

?Sxb: PGW-C <-> PGW-U, R14 29.244

?Peripheral interfaces: comply with existing 3GPP specifications.

1. Interfaces: In networking, interfaces are points of interaction between different network components or entities. They define how data and control signals are exchanged between these components.
2. Sxa and Sxb Interfaces:

• Sxa Interface: This interface connects the Control Plane (SGW-C) and the User Plane (SGW-U) of the Serving Gateway (SGW). It is used for communication and data exchange between the control-plane and user-plane functionalities of the SGW. The reference "R14 29.244" likely refers to a specific section or version of a 3GPP (3rd Generation Partnership Project) specification document that outlines the details and standards for this interface.
• Sxb Interface: Similarly, the Sxb interface connects the Control Plane (PGW-C) and the User Plane (PGW-U) of the Packet Data Network Gateway (PGW). This interface facilitates communication and data exchange between the control-plane and user-plane functions of the PGW. The reference "R14 29.244" likely pertains to the same 3GPP specification document for this interface.

SGW-C (Control Plane of Serving Gateway):

1. SGW-U Selection: This function involves the selection of the User Plane (SGW-U) for a specific user. It decides which SGW-U should handle the user's data transmission.
2. S1-U and S5/S8-U Tunnel IP Address and TEIDU Allocation: This function includes assigning IP addresses and Tunnel Endpoint Identifier (TEIDU) values for the S1-U and S5/S8-U tunnels used for user data transmission in the mobile network.
3. Access, Mobility, and Session Management: This function encompasses tasks related to allowing user devices to access the network, managing their mobility as they move between different network areas, and maintaining user sessions as they use various network services.
4. S-CDR Generation for Charging Roaming Subscribers: S-CDR (Serving-Call Detail Record) generation involves creating records that contain detailed information about the calls and sessions for roaming subscribers. These records are used for charging and billing purposes.
5. DDN Message Forwarding: DDN (Direct Data Notification) messages are used to indicate the occurrence of specific events in the network. SGW-C forwards these messages to appropriate destinations.
6. GTP-C Path Management: GTP-C (GPRS Tunneling Protocol - Control Plane) is used for signaling and control in the user plane. SGW-C is responsible for managing the paths for GTP-C messages.
7. LI over X1/X2/X3-c: This refers to Lawful Interception (LI) functionalities, which allow authorized parties (law enforcement agencies) to monitor and intercept communication as required by legal regulations. LI can occur over different interfaces, like X1, X2, and X3-c.

SGW-U (User Plane of Serving Gateway):

1. S-GW Forwarding Control: This function involves controlling the forwarding of user data between the Serving Gateway (SGW) and other network components.
2. Roaming Charging Data Collection: This function collects charging data related to roaming users, ensuring accurate billing and charging for services used while roaming on other networks.
3. Downlink Data Caching When UEs Are Idle: When user equipment (UE) devices are idle, downlink data caching allows frequently accessed content to be cached closer to the user, improving response times and reducing the load on the network.
4. GTP-U Path Management: GTP-U (GPRS Tunneling Protocol - User Plane) is used for actual user data transmission. SGW-U manages the paths for GTP-U messages.
5. LI over X3-u: Similar to the SGW-C's function, this refers to Lawful Interception (LI) capabilities over the X3-u interface, focusing on intercepting communication for legal purposes.

PGW-C (Control Plane of Packet Data Network Gateway):

1. PGW-U Selection: This function involves the selection of the User Plane (PGW-U) for a particular user's data traffic, determining which PGW-U should handle the user's data transmission.
2. S5/S8 Tunnel IP Address and TEIDU Allocation: The PGW-C is responsible for assigning IP addresses and Tunnel Endpoint Identifier (TEIDU) values for the S5/S8 tunnels used in user data transmission across the network.
3. Subscriber IP Address Allocation: This function pertains to assigning IP addresses to subscribers, enabling them to communicate over the network.
4. Centralized P-GW External Signaling Interfaces: The PGW-C handles external signaling interfaces that are used for communication with other network entities and systems.
5. Gx/Gy/Ga/RADIUS Session Control: These are protocols or methods for controlling sessions in the network, managing various aspects of user connections, policy enforcement, and authentication.
6. PCC Policy Control and Bearer Binding: Policy and Charging Control (PCC) involves defining rules and policies that govern how network resources are allocated and how users are charged for services. Bearer binding associates data flows with specific users and policies.
7. GTP-C Path Management: The PGW-C manages the paths for GTP-C (GPRS Tunneling Protocol - Control Plane) messages, which are used for control and signaling in the user plane.
8. LI X1/X2/X3-c: This refers to Lawful Interception (LI) capabilities over different interfaces (X1, X2, X3-c), allowing authorized parties to monitor and intercept communication for legal purposes.

PGW-U (User Plane of Packet Data Network Gateway):

1. Data Packet Forwarding: The primary function of PGW-U is to forward user data packets between the user equipment (UE) and external networks.
2. Roaming Charging Data Collection: Similar to the function in SGW-U, this involves collecting charging-related data for users while they are roaming on other networks.
3. SA and Service Control: This likely refers to Service Area (SA) management and service control, which involve managing the coverage areas of network services and controlling the services provided to users within those areas.
4. GTP-U Path Management: Similar to the GTP-C path management on the control plane side, this function involves managing the paths for GTP-U (GPRS Tunneling Protocol - User Plane) messages used for actual user data transmission.
5. LI X3-u: This is Lawful Interception over the X3-u interface, allowing authorized parties to monitor and intercept communication on this specific interface.

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