Peer-to-peer internet telephony using SIP

Abstract

P2P systems inherently have high scalability, robustness and fault tolerance because there is no centralized server and the network self-organizes itself. This is achieved at the cost of higher latency for locating the resources of interest in the P2P overlay network. Internet telephony can be viewed as an application of P2P architecture where the participants form a self-organizing P2P overlay network to locate and communicate with other participants. We propose a pure P2P architecture for the Session Initiation Protocol (SIP)-based IP telephony systems. Our P2P-SIP architecture supports basic user registration and call setup as well as advanced services such as offline message delivery, voice/video mails and multi-party conferencing. We also provide an overview of practical challenges for P2P-SIP such as firewall, Network Address Translator (NAT) traversal and security.

Supporting NGNs Core Software Services: A Hybrid Architecture and its Performance Analysis

“…The lookup operation performance is critical for many applications. For example, in VoIP the lookup time is directly translated into the end user's Quality of Experience (QoE) and should be kept typically below 200 ms [3]. In general, the lookup primitive should guarantee a short lookup time for QoS requirements enforcement (i.e., low latency), limited control message overhead, low memory and processors consumption on the NAPs, dependability (i.e., no false responses on lookup requests).…”

“…These servers gather regional traffic and forward it to clusters of other servers for users contacts retrieval purposes. Due to the employment of dedicated system administrators in each domain [3], the majority of the system costs are represented by maintenance and configuration. In addition, when the system load increases, new servers need to be added to avoid the creation of bottlenecks.…”

“…In addition, when the system load increases, new servers need to be added to avoid the creation of bottlenecks. Several load balancing systems have been proposed to smartly split the load including servers arranged along a Distributed Hash Table (DHT) [3].…”

“…For example, Johnston in [7] presents a SIP-using-P2P algorithm in which users' location information is directly stored in the DHT, without using traditional SIP Registrar and Location servers. In [3] the authors distinguish between super-nodes, i.e., nodes with high capacity (bandwidth, CPU, memory) and availability (uptime, public IP address), and ordinary nodes. Super nodes are organized in a DHT, i.e.…”

Stability analysis of peer-to-peer networks against churn

“…These kinds of networks diverge responsibility between participant computers in a network rather than conventional centralized resources. Such networks are useful for many purposes like file sharing, telephony, media streaming (radio, video), discussion forums etc [2]. Peers in p2p networks are connected among themselves by some logical links forming an overlay above the physical network [3].…”