 concern regarding both network protection against intentional damage Understanding Changing Telecommunications - Building a Successful Telecom Business (sabotage from hackers and intruders) and fraud detection and prevention. A very strict authorization and authentication is therefore necessary. At the service and content layer the network can be flooded, leading to denial of service. Virus attacks and other malicious programs hit the contents. Data get corrupted. Unauthorized users gain access to the communication network. False data is inserted. Money can be transferred to the wrong receiver. B2B and B2C transactions are disturbed. What can we do with the network, to protect it? Let us use a metaphor and consider the network as a house, that we want to protect. We can close the doors and windows and lock them. Then we can give a key only to those we want to access to our house. This is an organizational way of protection, similar to network access control and an encryption key. You could improve data encryption through rotation of the key. Think of this as having your own personal locksmith periodically show up at your home and change all the locks on your doors and windows. You dictate how often the key should be changed. Setting up a fence is another option, with the firewall as a correspondence. The firewall acts as a filter, letting authorized traffic in and locking other traffic out. One single way of protection is not enough, but there are protection concepts that are quite broad, with IPsec as the most well-known one. With this in mind it is obvious that the security plan in reality is distributed all over the network. Therefore, one way is to attach a security part to all other fundamental plans to ensure that they are all functioning properly. However, there would still be a need to have a chapter with no correspondence in the other plans, with the overall security policy and the translation from security language to concrete measures in the network. A common complementing or alternative way is to use