Packet Core and Service Continuity Flashcards

What is the role of the CHF (Charging Function) in Ericsson's 5G core?

Answer: Collecting online/offline charging data from SMF/PCF and interfacing with the billing system

The CHF (Charging Function) is the 5GC network function that processes charging triggers from the SMF and PCF, converging online (real-time credit control) and offline (CDR-based) charging.

In Ericsson's EPC, what is the Gx interface used for?

Answer: Carrying policy and charging control messages between the PCRF and PGW (PCEF)

The Gx interface is a Diameter-based interface between the PCRF and the PGW's PCEF, used to push QoS rules and charging policies per session.

What does 'CUPS' (Control and User Plane Separation) enable in Ericsson's evolved packet core?

Answer: Separating SGW and PGW control plane functions from their user plane functions, allowing them to scale independently

CUPS decouples the control plane (SGW-C, PGW-C) from the user plane (SGW-U, PGW-U), enabling the user plane to be distributed closer to the network edge while control remains centralized.

In Ericsson's 5G, what is the LADN (Local Area Data Network) feature?

Answer: A PDU session type that gives UEs access to a local data network only when within a specific geographic area

LADN allows UEs to connect to local data networks (e.g., factory systems) only when physically within the LADN service area, supporting MEC and Industry 4.0 use cases.

Which Ericsson feature supports handing off a VoLTE call from LTE to the PSTN when the subscriber moves out of LTE coverage?

Answer: SRVCC (Single Radio Voice Call Continuity)

SRVCC (Single Radio Voice Call Continuity) allows an active IMS voice call to be transferred from the LTE/IMS packet domain to the circuit-switched WCDMA/GSM domain without dropping the call.

In Ericsson's multi-access edge computing (MEC) deployments, where is the UPF typically placed?

Answer: At or near the RAN edge (e.g., in the DU/CU site) to minimize latency for local applications

For MEC use cases, the UPF is deployed at the RAN edge so that user plane traffic is offloaded locally without traversing the central core, achieving ultra-low latency.