ETCP Packet Core and Service Continuity

Question 1

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

Accepted Answer

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

Answer

Provides IP address allocation to UEs

Answer

Authenticates subscribers using AKA procedures

Answer

Manages inter-PLMN roaming policy

Question 2

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

Accepted Answer

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

Answer

Encrypting control plane messages between HSS and MME

Answer

Providing DNS resolution for subscriber domains

Answer

Managing inter-RAT handover between LTE and Wi-Fi

Question 3

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

Accepted Answer

N6

Answer

N3

Answer

N9

Answer

N4

Question 4

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

Accepted Answer

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

Answer

Bonding multiple physical UPF servers for higher throughput

Answer

Routing voice and data to separate UPF instances by APN

Answer

Synchronizing UPF clock sources across data centers

Question 5

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

Accepted Answer

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

Answer

Providing radio resource allocation per TTI

Answer

Managing the physical transport between eNB and core

Answer

Storing raw CDRs (Call Detail Records) for billing

Question 6

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

Accepted Answer

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

Answer

A physical fiber connection between the PGW and internet exchange

Answer

A dedicated signaling link between MME and HSS

Answer

An inter-core interface between two operators' EPC nodes