To add an interesting twist
to
the progression, let’s talk about roaming. The
examples I’ve presented thus far assume that the
service equipment and AAA server are all under the direct control and
ownership of a single entity, the
user’s
home organization (UHO). But what happens when the service equipment
is owned and operated by another organization? This model is called
roaming, and the Roaming
Operations Working Group (Roamops) has been formed to explore this
situation. Roaming is actually quite common: revisiting an earlier
example, a user connecting to a set of dial-up ports that his ISP is
renting from a larger service provider is roaming, since the service
equipment is in another provider’s domain.
The same combinations of authorization sequences—agent, push,
and pull—are possible with roaming. Figure 1-6 through Figure 1-8 depict
typical roaming authorization sequences.