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Peer-to-peer Internet telephony
1. Peer to peer Internet telephony challenges, status and trend Kundan Singh Oct 2010
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6. What is P2P telephony? PBX, H.320, H.324, RTMP, Asterix/IAX, B2BUA, SBC, … SIP, H.323, XMPP/Jingle, Gtalk, RTSP, RTMFP, … Skype, P2P-SIP, … signaling + media signaling media
7. What is P2P telephony? enrollment service login server varies centralized incentive driven caching, delay storage, split-and-store implementation driven (mostly) unstructured File sharing open problem proprietary software malicious nodes caching useless; bounded load overloaded super-nodes efficiency open protocols + algorithms proprietary/close needs gateway inter-operability structured DHT efficiency guarantee Kazaa based unstructured topology P2P-SIP Skype
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10. What are super peers? How is it implemented? Use DHT among super-peers 1 10 24 30 54 38
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14. What are the benefits and limitations? * Node capacity of 10 register/s and refresh/call rates of 1/min more than 16 million peers (super-nodes) in the network lookup = O(logN) #connections one or two steps Call setup latency upper bound; catastrophic failure unlikely trust (most) super nodes; probabilistic maintain = O((logN) 2 ) user count ≈ 2 {node-capacity}* uptime, churn, … Structured P2P (Chord) no guarantee server redundancy (1-(1-R) P ); catastrophic failure possible; bulk load Availability connect to trusted nodes only trust provider; boolean Security #connections most efficient Efficiency user count K-degree no limit server count ≈ {server-count} Scaling Unstructured P2P (blind-search) server-based
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Editor's Notes
Peer-to-peer (P2P) systems inherently have high scalability, robustness and fault tolerance because there is no central point of failure and the network self-organizes itself. Skype is a popular and dominant example of P2P VoIP. The IETF P2P-SIP working group was formed to explore a P2P architecture for SIP-based telephony and beyond. Traversal through NATs and firewalls is a major challenge in getting end-to-end media in a distributed P2P network. Another major problem of P2P VoIP is security against malicious peers. I will present an overview of P2P VoIP, the challenges, status and current trend in practice. In particular you will learn the advantages and problems associated with P2P VoIP, comparison of various architectures, design decisions and implementations, and a summary of IETF effort.
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