Information Technology Reference
In-Depth Information
Load Balancing
Cluster (LBC)
Regular Node
Regular Node
Super Node
Regular Node
Regular Node
Load Balancing
Cluster (LBC)
Load Balancing
Cluster (LBC)
Regular Node
DHT Ring
Super Node
Super Node
Regular Node
Regular Node
Regular Node
Super Node
Load Balancing
Cluster (LBC)
Regular Node
Regular Node
FIGURE 3.10: A semi-structured P2P network architecture [Ohnishi et al.,
2007].
a Gnutella random network). Depending upon the clustering status of the peer,
UBCA redirects the requests to appropriate peers in the system.
Specifically, UBCA comprises three different layers of components: data,
decision logic, and communication, as shown in Figure 3.12. The data layer
gathers and maintains information for making clustering decisions. The de-
cision logic layer employs utility functions to evaluate clustering options and
select appropriate data items for fetching. The communication layer is respon-
sible for the information exchange among peers.
The information gathered at the data layer is mainly about the qualities
and costs of different resources. Utility values can then be computed as qual-
ities less costs. A peer decides to join a cluster if the latter can provide a
positive overall utility among all resources concerned. After joining the clus-
ter that provides the maximum aggregate utility, the peer can then use the
decision logic layer to select the most important (i.e., with the highest utility
gain) resource for retrieval.
With this UBCA architecture, Lagesse and Kumar [Lagesse and Kumar,
2007] showed that the average latency as well as bandwidth utilization are
greatly improved.
Hsiao and King [Hsiao and King, 2003] also proposed a very interesting
hybrid P2P network architecture for handling mobility of peers. Indeed, the
proposed architecture, called Bristle, is designed for managing mobile devices
participating in a P2P network. As shown in Figure 3.13, the Bristle archi-
tecture consists of two different layers: the stationary layer and the mobile
layer. Machines participating in the stationary layer are immobile, i.e., having
fixed IP addresses. On the other hand, mobile devices need to join the mobile
layer. Consequently, the stationary layer is to be implemented by a DHT, e.g.,
Chord, while the mobile layer is to be supported by only a random network.
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