P2P Network Architectures - Peer-to-Peer Computing: Applications, Architecture, Protocols, and Challenges - page 46

•Nomadic Support: Users can have nomadic access to the network as
they can obtain their credential information via the Internet.
•Mobility Support: Mobility is enabled by using various wireless access
technologies (e.g., Wi-Fi).
•Unique Benefits of the Architecture: The proposed architecture can
potentially combine the best of both telecom services and P2P services
because it is designed to provide QoS guaranteed P2P services in a secure
and trusted telecom environment. Thus, it is expected that users would
agree to pay for such services.
The detailed service provisioning mechanisms are described below.
3.5.1 AAA Tasks
Admission control of peers is handled mainly by the bootstrap server and
some bootstrap peers. Specifically, a new peer needs to contact the bootstrap
server first. The new peer can then obtain the locations (e.g., IP addresses)
of a bootstrap peer. Of course, if the new peer joined the system before, it
might have cached the address of a previous bootstrap peer so that it can just
directly contact the latter in this instance. In the whole admission process,
the new peer works with the assigned bootstrap peer. The bootstrap server
together with the bootstrap peer verify the credential information of the new
peer.
Mutual authentication, between the new peer and the system, is also han-
dled via the bootstrap server. Upon successful authentication, an authorized
token signed by the AAA server is sent to the new peer and incorporated into
the JOIN signaling packet to the bootstrap peer. The token is also used in
subsequent interactions between the new peer and the system such as getting
an authorized QoS level.
3.5.2 Charging
Charging requires cooperation among peers, both the uploading (i.e., serv-
ing or supplying) peer and the downloading (i.e., served or consuming) peer.
Specifically, the uploading peer requests the downloading peer for some “credit
units” which are obtained from the charging system. On the other hand, the
charging system also helps the uploading peer to collect, verify, and validate
the credits from the downloading peer.
3.5.3 Dynamic QoS
Each participating peer can modify the QoS for any particular session, as
illustrated in Figure 3.15.
Specifically, if a peer demands a certain QoS guarantee, it will be charged.