Rapid increase of high definition video applications and data-sharing applications requires a large transmission bandwidth in every network domain. To stably serve the applications, Internet service provider (ISP) has increased the packet transmission capacity of network device and the number of transmission lines in backbone networks, while trying to provide more transmission bandwidth to an end user by optical networking technologies in access networks. At the same time, ISP has introduced various kinds of traffic engineering mechanisms and solutions to efficiently control the traffic of over-the-top (OTT) applications in busy service hours. A recent important issue is how to efficiently handle the traffic of peer-to-peer (P2P) applications. It is observed that P2P applications consume half of transmission bandwidth in the access network domain. However, although the transmission efficiency of P2P data traffic is quite low in EPON because of the behavioral features of P2P applications, it is difficult to efficiently control P2P traffic with general traffic engineering methods.
In this dissertation, a new P2P control framework are researched and evaluated to achieve a high degree of efficiency in serving P2P applications in EPON. The objectives of the traffic engineering mechanisms that are proposed in the research based on the framework are summarized to be three topics. The first objective is to achieve a high degree of efficiency in network resource allocation in a backbone network. The proposed mechanisms achieve the objective by an adaptive control of peer list so that the long-travelling P2P traffic between remote peers in different backbone networks can be minimized, called P2P traffic localization. The second objective is to achieve a high degree of efficiency in transmission bandwidth allocation in the EPON domain. The proposed mechanisms achieve the objective by the selective control of seeder and multicast-based batch transmission of P2P data traffic. The final objective is to achieve the first and the second objectives by the simple control of P2P control message, which can reduce the CAPEX and the OPEX of ISP. It is achieved by the centralized P2P control framework in management of peer list and P2P data caching.
First, the recent patterns of OTT application traffic are dealt with and their effects on the performances of Internet services are analyzed. Here, TDM-PON technologies are presented and the protocols of the objective access network technology, EPON, are explained in detail. The features of representative P2P applications, that is, P2P file-sharing and P2P video streaming, are discussed and types of P2P traffic control mechanisms are also analyzed and their features are compared. Using the summarized features of related works, the objectives of the proposed P2P control framework are clarified. The common architecture of control framework and the logical configuration of related control systems are also explained.
Second, an adaptive P2P transmission control mechanism is proposed to efficiently serve P2P file-sharing applications in EPON. Here, the behavioral features of P2P file-sharing applications in EPON and the resultant effects on data transmission efficiency are analyzed. To support P2P file-sharing services using a minimum amount of network resources both in EPON and in a backbone network, a cache-based hybrid P2P (CH-P2P) mechanism is proposed. CH-P2P distributes preferential files to OLTs by the hierarchical caching method and minimizes the amount of long-travelling P2P traffic in a backbone network domain, which is defined as P2P traffic localization. Using the multicast-based batch data transmission, data traffic of P2P file-sharing are also delivered to a number of clients by a minimum transmission bandwidth in the EPON domain. It is clarified that the performance enhancements are achieved by the optimal combination of the architectural feature of EPON and the behavioral feature of P2P applications in the design of P2P session control.
Third, the efficiency of P2P video streaming applications and their protocol features are discussed. The issue in delivery of P2P streaming data in EPON is analyzed considering the architectural feature of EPON. A proposed localized multicast-based P2P (LM-P2P) mechanism controls generation of P2P video streaming sessions so that later clients can be served by a local multicast seeder in the same OLT domain (EPON). By the localization of P2P streaming sessions in the intra-OLT domain and the multicast-based streaming, P2P video streaming applications can be served by a minimum amount of network resources without degradation of video quality. The performances of LM-P2P are validated by numerical simulations and practical test results.
The proposed P2P control framework and traffic engineering mechanisms achieve the objective high degrees of efficiencies in P2P traffic localization and transmission of P2P traffic in EPON without complex control of P2P data sessions. The practical advantages of the proposed framework related to deployment in real networks are as follows: First, a costly packet analysis function such as DPI which is required to control P2P peer session and data caching is not needed to be employed in access network devices such as ONU and OLT. It is deployed only in a peer control gateway (PCG) that is located in a core network. As a result, the CAPEX and the OPEX, which are the important issue for ISPs and contents providers, are not large. Second, by the centralized control of peer sessions in P2P session setup states, the complexity in handling of P2P sessions is minimized, while reducing the risk of direct control of user data. Because P2P data sessions between peers are generated spontaneously by the control of PCG, access network devices are not needed to directly control the data packets of P2P applications. Third, because the proposed framework and mechanisms can run as an overlay protocol in the application layer, modification of standard transmission protocol of EPON is minimized.
The important feature of the proposed framework is that the P2P control mechanisms are designed by the unique features of P2P applications and their behavioral patterns in access networks. It considers the macro performances in the entire network domain, not the micro performance that can be achieved by control of transmission bandwidth in a single network device. Thus, high degrees of efficiencies can be achieved from the backbone network to the end user without degradation of qualities of applications.. The proposed approach can also be employed in the control of other OTT applications.
