Topology Control - Peer-to-Peer Computing: Applications, Architecture, Protocols, and Challenges - page 72

Topology control for wired and wireless P2P systems is still a largely open
research topic. Indeed, researchers have not investigated an optimized “inter-
play” between the application layer, network layer, and even the physical
layer (in a wireless setting). In many proposed algorithms, network or phys-
ical layer control actions are used (e.g., controlling who is the neighbor). An
important next step in topology control research is to propose an e cient
“cross-layer” design for P2P systems. Moreover, researchers should come up
with a “weighted” combination of the several localized metrics used for setting
up new peer connections.
Furthermore, how the existing topology control policies would impact the
system evolution subject to different operating conditions (such as existence of
non-cooperative peers, selfish peers, or even malicious peers) is an interesting
further research topic. Most notably, existence of “free-riders” and “white-
washers” could possibly lower the life-time of the file sharing network signifi-
cantly because such users would definitely not contribute to the network by not
acting as replaying nodes. Furthermore, an even more detrimental situation
would be having some malicious users who drop important control messages
or fake them, possibly leading to the formation of an ine cient cluster.
4.9 Review Questions
1. Why is topology control important?
2. What are the general techniques used in structured topology control?
3. How do you define the topology mismatch problem?
4. How is network coding useful in topology control?
5. What is the major challenge in wireless topology control?
6. What are the major di culties in formulating a topology control game?