3. Main principles and components of a defense plan

3.1 General

The defense plan is the ultimate barrier for protecting the network in the event of a major incident, when all other measures, margins, protections and group control systems have failed to stop the chain of incidents and limit their consequences.

However rare major incidents may be, it is generally accepted that it is advisable to protect against them, even if the specific devices required represent a significant investment and have consequences for network operating costs. Indeed, these investments are all the more profitable when the consequences of major incidents are severe, both for the network and for customers, and when restoring service is long and difficult.

A defense plan aims to :

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