Due to the increasing popularity of Peer-to-Peer (P2P) computing, the information technology industry and standardization organizations have started to direct their efforts on standardizing P2P algorithms and protocols. The Internet Engineering Task Force (IETF) has recently formed the Peer-to-Peer SIP (P2PSIP) working group for enabling serverless operation of Session Initiation Protocol (SIP). This chapter introduces the P2PSIP by presenting its background and purpose, operational principles, current status, and application areas. The focus is on the challenges and problem areas from the viewpoint of standardization and related research. The mobile- and heterogeneous environments are considered with special care. The authors provide a glance to the existing and emerging solutions that may be used in tackling the mentioned challenges and thus paving the way for successful deployment of P2PSIP in mobile environments.
Background: Peer-To-Peer Sip
The scientific background of P2PSIP is built on the University of Columbia’s P2PSIP (Singh & Schulzrinne, 2004) and the College of William&Mary’s SOSIMPLE (Bryan et al., 2005) projects. Based on the results of these early projects and multiple ad-hoc meeting sessions between the interested parties during 2005-2007, IETF formed the P2PSIP working group in 2007 for developing standards for serverless use of SIP. The goal has later extended towards a more general P2P architecture, where the applications can also utilize P2PSIP overlay directly, instead of limiting the usage to only SIP-based communication. The focus of P2PSIP is in the general functions providing decentralized node- and resource location and communication, and the essential supportive functions that ensure the secure and unrestricted access to the mentioned services. As the focus is tightly in building a general-purpose enabling technology, the supplementary services are outside the scope of P2PSIP.