Functional Requirements Document (FRD) – Dual APN Support

Feature: Dual APN Management in zWAN SDWAN CPE
Version: 0.9

1. Overview

This document defines the functional requirements for implementing Dual APN support in a single cellular modem module (e.g., Quectel RM520).
The solution enables two independent data connections using two APN profiles operating concurrently, each with its own configuration and network interface, providing segmented network access (e.g., public and private).
The system must support connection management, monitoring, event reporting, and persistence.

2. Functional Requirements

FR-1: Dual APN Support in a Single Module

• Support configuration and operation of two independent APNs using a single modem.

FR-2: Independent APN Configuration

• Each APN profile must be configurable individually, including:
  • APN Name
  • Username
  • Password
  • Authentication Type (PAP, CHAP, or None)

FR-3: Simultaneous APN Sessions

• Both APN sessions must run concurrently and be maintained independently (e.g., FR-1 and FR-2 contexts active simultaneously).

FR-4: Persistent Configuration

• All APN context configurations must persist across device reboot or power cycle.

FR-5: Context Lifecycle Management

• Provide commands to manage APN contexts:
  • add-context: Create a new APN configuration
  • list-context: Display current APN configurations and status
  • delete-context: Remove an existing APN configuration

FR-6: Dedicated Host Interface per APN

• Each APN must be mapped to a distinct host network interface (e.g., wwan0, wwan1).

FR-7: Independent Default Gateways

• Each APN interface shall have its own default gateway for routing separation.

FR-8: Support for Public and Private Segmentation

• One APN interface can connect to a public network while the other connects to a private network simultaneously.

FR-9: Individual Connection Monitoring

• Each APN session shall be monitored separately (e.g., ping or QMI-based checks).

FR-10: Auto-Reconnection

• The system must auto-reconnect an APN session on failure (e.g., IP release, modem reset).

FR-11: Alerts and Events

• Generate events/alerts (e.g., via syslog or event system) on:
  • Connection established
  • Connection loss
  • Reconnection attempts
  • Final failure after retries

FR-12: Reporting

• Application-level and bandwidth reports must be provided per APN context (e.g., wwan0:APN0, wwan1:APN1).