F igure 3 below shows centralised access control and federated access to the Internet. The essence of the arrangement is that access control is managed centrally, but Internet connectivity is provided by the federated network.
Figure 3: The elements of federated access to the Internet.
The observant reader will realise that LI has become more problematic. Identity information is held at the central location, but traffic between a mobile terminal and the Internet is dealt with by the federated network. Such traffic is never seen at the central location. Traffic may be seen by the federated network, though.
The feature of this arrangement as compared with figure 2 is that there is no backhaul to the central location. This would generally be cheaper than using such backhaul. A service provider is always under economic pressure to reduce the costs of operation.