Packet Core and Service Continuity Flashcards

In Ericsson's EPC, what does the SGW (Serving Gateway) do?

Answer: Acts as the mobility anchor for user plane data during intra-LTE handovers and idle-mode paging

The SGW anchors the user plane bearers during handovers between eNBs, buffers downlink data during UE paging, and routes packets between the eNB and PGW.

What is the purpose of the GTP (GPRS Tunneling Protocol) in Ericsson's packet core?

Answer: Tunneling user IP packets between EPC gateway nodes (SGW–PGW) and between eNB and SGW

GTP-U tunnels encapsulate user plane IP packets over the S1-U (eNB–SGW) and S5/S8 (SGW–PGW) interfaces, providing subscriber-level tunnel isolation.

In Ericsson's 5GC, which interface runs between the UPF and the Data Network (internet)?

Answer: N6

The N6 interface connects the UPF to external data networks (e.g., the internet or enterprise networks), carrying the unencapsulated subscriber IP traffic.

What does 'UPF chaining' allow in Ericsson's 5G user plane architecture?

Answer: Linking multiple UPFs in sequence so traffic passes through different processing functions (e.g., traffic inspection, NAT, firewall) in a service function chain

UPF chaining (via Service Function Chaining) routes packets through a sequence of UPF instances or VNFs, each applying a specific processing function before forwarding.

In Ericsson's packet core, what is PCRF (Policy and Charging Rules Function) responsible for in LTE?

Answer: Defining and enforcing QoS policies and charging rules per bearer or subscriber session

The PCRF dynamically sets QoS parameters (bandwidth, priority) and charging rules for each subscriber session, enforcing operator policies in real time.

What does the term 'PDN Connection' refer to in Ericsson's LTE/EPC architecture?

Answer: The logical association between a UE and an external Packet Data Network (e.g., internet), anchored at the PGW

A PDN Connection is the end-to-end logical path from the UE through the EPC to an external data network, identified by an APN and maintained as long as the UE is active.