Page Comparison

Overview

First of all we split between critical- and non-critical services:. Everything that has to do with customer is "critical". All that has to do with service staff is "non-critical" at the time.

Failover Layers

1. NMS Prime GUI

no failover at the time

2. Apache

no failover at the time

3. Database

Normal MySQL / MariaDB failover cluster with N nodes. Possible Solutions:

1. MaxScale
2. MariaDB Galera Cluster (not tested)

4. NMS Prime Lower Layers

We differ between the master and N x slave NMS PRIME instances. The primary instance is also running the NMS PRIME GUI. Any changes in GUI will trigger realtime changes in any the master config(s), like DHCP , and TFTP, . .. This is done via Laravel Observers or Jobs (e.g. Modem Observer).

The slaves are running on separate machines without a GUI. They are rebuilding DHCP, BIND, and TFTP configfiles on a regular base (e.g. 1 hour) e.g. via cronjob. The slaves are independent from Master and they are only connected towards MariaDB SQL cluster via a SQL read-only connection. So any changes in Master will be directly distributed towards SQL cluster and later automatically fetched from the slaves.

This concept offers:

1. a Master with real-time changes towards all critical configs
2. redundant slaves who is independent off Master
3. a redundant database with load-sharing possibility
4. Load-Sharing for either DHCP, DNS and TFTP for all Modems

5. Critical Services

ISC-DHCP

Normal ISC-DHCP failover with Master-Slave Concept:

• https://kb.isc.org/docs/aa-00502
• https://www.madboa.com/geek/dhcp-failover/

Slaves rebuild their DHCP configs by them self after a defined time (see above).

DNS / BIND

Slaves rebuild their configs by them self after a defined time (see above).

More research required, but a good starting point could be here:

• https://www.lisenet.com/2018/configure-bind-dns-servers-with-failover-and-dynamic-updates-on-centos-7/
• https://serverfault.com/questions/236096/isc-dhcpbind-with-failover-and-dynamic-updates-can-the-secondary-bind-update-d

TFTP

Cronjob at slave will rebuild all configfiles on a recurring basis (e.g. every hour). In NMS Prime this could simply be done by running

Possible Cronjob(s) for Slaves

php artisan nms:dhcp && systemctl restart dhcp

php artisan nms:configfile

Github TODO: #687