P2P streaming architectures
Overview of Joost
Traffic characterization and underlying mechanisms
UDP vs. TCP utilization
Download video traffic
Upload video traffic
P2P streaming applications taxonomy
20 s–2 min
Network locality and geographic distribution
Load balancing: P2P systems are known for their ability to autonomically balance computing resources. This is achieved well in P2P file sharing applications where time constraints are not so stringent, which allows for better resource optimization and overlay management. However, P2P streaming poses time limits which make this task harder. Methods which cater for near-optimal load balancing of computing resources within the limits imposed by RT streaming will acquire importance since mobile, thin terminals will demand more effective off-loading mechanisms.
Network locality: streaming without considering ways for optimizing the use of network resources is bound to pose serious hurdles, since this clashes with the modus operandi of network operators and ISPs. Methods which allow prioritizing connections based on geographical proximity as well as mobility patterns have considerable potential in terms of network efficiency.
Fairness and free riding: this is one of the issues in common to all type of P2P applications, not merely P2P streaming. There must be a way to prioritize connections based on mutual resource sharing. There is, on the other hand, a strong trend towards free riding (i.e., peer who get resources without sharing their own), a problem which dramatically degrades the performance of P2P. In the case of P2P streaming, it seems easier to tackle this issue. Appropriate mechanisms, coupled with economic models (e.g., based on incentives) will be required.
Start-up delay: this is excessive in current systems, which makes the user experience poor if compared to conventional TV broadcasting. Switching channels is also too slow, which makes zapping impossible. This seems a hard problem since buffering time cannot be reduced in current best-effort networks.
Mobile user: current P2P streaming systems impose requirements (in terms of computational and access network capability) that are beyond the reach of state-of-the-art mobile phones or PDAs. Mobile P2P streaming poses some challenging research issues that are bound to attract vivid attention.