Jani Hautakorpi

Interconnecting P2PSIP and IMS

Interpersonal communication using the information networks can be accomplished in many different ways. Users may communicate, for example, by using a specific communication application on an end-user terminal, typical mobile phone, or IP Multimedia Subsystem (IMS) client. Quite often there is no interconnection mechanisms between these different communication methods, and this is emphasized with regards to various communication applications. We propose an architecture for interconnecting Peer-to-peer Session Initiation Protocol (P2PSIP) and IMS networks. The actual gateway, that enables the interconnection, is seen as a peer in the P2PSIP side and as an application server (AS) in the IMS side. Furthermore, we present a prototype from the proposed interconnection architecture.

Load balancing for structured P2P networks using the advanced finger selection algorithm (AFSA)

Structured Peer-to-Peer (P2P) networks, such as networks based on Distributed Hash Tables (DHTs), can be enhanced by using load balancing mechanisms. Current load balancing mechanisms are either trying to achieve even distribution of objects among nodes, make the address space as evenly populated as possible, or both. However, we have taken a different approach to load balancing in this paper and we have defined the Advanced Finger Selection Algorithm (AFSA) which is not focused on balancing the objects among the nodes and does not require evenly populated address space. AFSA is an algorithm which changes the way how nodes are selected as fingers to the overlay routing tables in structured P2P networks. We implemented the AFSA algorithm for both Chord and Bamboo and we evaluated it with simulations.

Framework for Decentralizing Legacy Applications

Today many Peer-to-peer (P2P) applications are widely used on the Internet. Especially file sharing is a popular P2P application that has, at least partially, replaced the centralized file sharing infrastructure. However, there are still a number of legacy applications that utilize a centralized infrastructure as opposed to a decentralized approach. In this paper we present a generic framework for decentralizing legacy applications. Even though we focus especially on Voice over IP (VoIP), email, and web applications, we believe that our framework could also be utilized with other legacy applications. A notable feature of our framework is that it does not require any changes to legacy applications.

Effect of head of the line blocking on session initiation protocol session establishment delays

We have studied the effect of head of the line blocking (HOLB) on session initiation protocol (SIP) session establishment delays. Our results are based on experiments performed in a test bed and on the public Internet. We used the stream control transmission protocol (SCTP) as a transport for SIP because SCTP can be configured to suffer or to avoid HOLB. Our experiments show that the effect of HOLB on session establishment delays generally starts to be significant starting at fairly low packet loss rates. However, there are scenarios where network conditions are good enough to make the effect of HOLB insignificant.