User Guide

User Guide – OWL Self-Monitoring Concepts

Contents

Watchdog Concept Introduction

................................................................................................................. 2

Hardware Watchdog ......................................................................................................................................... 2

Brief Description ............................................................................................................................................ 2

Detailed Description .................................................................................................................................. 2

Router Timing ............................................................................................................................................ 2

Software Watchdogs ........................................................................................................................................ 2

Supervised Applications ........................................................................................................................... 2

Mobile Network Registration Supervised .............................................................................................. 3

Uptime, Standard Ways to Reboot and System Log ........................................................................... 3

Uptime .................................................................................................................................................... 3

Standard Reboots ................................................................................................................................. 4

System Log ............................................................................................................................................ 5

Continuous Connectivity Features .................................................................................................................. 5

Check Connection to Mobile Network ................................................................................................... 5

Backup SIM Card or APN ......................................................................................................................... 6

Backup Routes System ............................................................................................................................ 6

Daily Reboot ............................................................................................................................................... 7

VRRP Check Connection .......................................................................................................................... 7

OpenVPN Check Connection ................................................................................................................... 8

User Guide

Introduction

This document explains the operation of watchdogs in OWL cellular routers. The hardware

watchdog and software watchdogs are described to make it clear why the router reboots.

Continuous connectivity features are described subsequently to understand the possibilities of

connection checks and monitoring in OWL cellular routers.

Hardware Watchdog

Brief Description

The routers have an internal hardware watchdog circuit. This extra component oversees the

operation of the router’s processor. The processor sends a keep alive signal to the watchdog

regularly, so the watchdog knows the processor is still running. If the watchdog circuit doesn’t get

any keep alive signal (processor stuck), it will reboot the router.

Detailed Description

The watchdog in the routers is an extra component on the PCB, not integrated in the router’s

processor. The watchdog component has its own independent internal timer and it doesn’t share

the clock with the processor or other peripherals. There is a keep alive signal route from the

processor to the watchdog circuit WDI input (Watch Dog-In) and the watchdog responds to level

changes of this signal (edges). The router’s processor sends the keep alive signal very early after

initialization - it is one of Linux kernel drivers waiting on the prompt from one of the initialized

applications - so when the keep alive signal is sent, it is the awaited information that the system

was initialized successfully. The frequency of the refreshing signal from the processor is higher

than 1 Hz. If the watchdog circuit doesn’t get the refreshing pulse in the expected time, it will reboot

the whole router (equal to turning the router off and on). Not only the processor is reset, but a

global reset is done (including all the peripherals like memories, etc.).

Router Timing

In OWL routers the watchdog operates in one mode only - it always waits 60 seconds - at the

initialization and after the first refreshing pulse is delivered. (So the reboot is done up to 60 seconds

when the processor gets stuck).

Software Watchdogs

Supervised Applications

There is a daemon watchdogd supervising the operation of the key daemons pppsd and bard.

These key daemons handle the connection to WAN (establishing connections and backup routes)

and refresh the watchdogd daemon. The Watchdogd daemon is refreshing the hardware

watchdog. If there is a problem in pppsd or bard (e.g. stuck, looped or terminated unexpectedly), it

will stop to refresh the watchdogd daemon, which will stop to refresh the hardware watchdog

component. This will cause the reboot of the router.