16 Introduction
An important aspect related to trust zone crossing is the synchronization of authentication data.
Basically, trust zones need to have a consistent and up-to-date view of the clients' authentication
information that is shared across the whole network. In this line the CC ensures that changes are
replicated and synchronized across the various available servers and databases, so that identity
federation is achieved.
It is also relevant to notice that the authentication process is based on the use of ICMP packages.
Succinctly, the client submits an access request to the border patrol. The border patrol responses by
sending an authentication request through an ICMP package. Upon reception of the ICMP package
the client replies with a ticket containing the cookie issued by the remediation service in the trust zone
of origin and its corresponding access rights. If health status and permission match the minimum
requirements of the target trust zone, the client is granted access. Otherwise, the border patrol denies
the request.
Fig. 1–3 Trust Relationships
If the border patrol denies the request, then no remediation will be available. Access is either granted or fully
denied.