Future IT systems have to protect the user's privacy. An important approach for privacy protection is to use several virtual identities, VIDs. Attackers want to extend the VIDs in order to learn more about the user. Often, this VID approach is only considered on the application layer, but the communication system also must be designed for supporting VIDs. The thesis presents two formalized methodologies. The first methodology provides for evaluation of the VID protection capabilities of communication systems. The second methodology provides for improvement of the protection. The methodologies are introduced in a general way and are applied to Mobile IPv6 in order to proof their usefulness. A new architecture for IP-based mobility management is developed and is evaluated with respect to its VID protection capabilities.