For designing a communications switch that has to provide 24/7 availability, a self-monitoring architectural style can be used. A self-monitoring architecture is a system architecture in which the system is designed to monitor its own operation and to take some action if a problem is detected.
For a system which require availability this architecture is more suitable. It is suitable because even some failure occurs this system is designed in a way to resist and recover. As the system is not a safety critical one, protection system architecture does not suit well than a self-monitoring system.