Resilience requirements to support delivery of critical services are established for all operating states (e.g. under duress/attack, during recovery, normal operations)
The security arrangements required for critical online services, such as security features, service levels, and management requirements, are carefully defined in advance. Online services include e.g. connections, networks and network security solutions (e.g. firewalls).
The security features of online services can be e.g. the following:
For example, when the fault tolerance of a telecommunication network is critical, it can be further improved by procuring basic network services through several routes and through several service providers.