CDN与P2P混合网络中Peer节点负载均衡研究

【作者】 姜小平；

【导师】 任立勇；

【作者基本信息】 电子科技大学 ， 软件工程， 2011， 硕士

【摘要】 CDN与P2P混合网络,具有较好的可扩展性、自适应性与健壮性,从而能够为分布在异构网络环境中的大规模用户提供服务质量保证,并尽可能节省服务器成本开销。在CDN与P2P混合网络中Peer节点负载均衡是使其有效运行的重要因素之一。本文研究CDN与P2P混合网络中Peer节点负载均衡算法,主要解决访问请求不均匀造成的负载不均衡问题。解决访问请求不均匀造成的负载不均衡主要算法有:基于复制技术的算法、基于流言传播的算法、基于意识路由的算法、基于虚拟节点的算法。基于复制技术的算法将副本存放在将来访问请求到来的位置,已有的基于复制技术的算法在副本存放位置上作了假设,即现在访问请求到来的位置也将是未来访问请求到来的位置。本地域外Peer节点负载均衡算法——改进CDN-PR算法,在CDN-PR副本算法思想上进行了改进,未改进的算法假设副本存放的位置是将来访问请求到来的位置,这个假设有些时候是正确的,但也存在与假设相反的情况,缺少理论的支撑,因此引入了马尔科夫预测模型,预测将来资源访问请求到来的位置,其次是因为CDN-PR副本算法适合于CDN网络中Peer节点负载均衡;马尔科夫预测模型根据访问请求现在到来的区域及其变化趋势,预测访问请求在将来某一特定时刻可能到来的区域,为副本位置决策提供了依据。本地域内Peer节点负载均衡算法——改进多次尝试请求RR(Request Retries)算法。在多次尝试请求算法思想上,通过马尔科夫预测模型预测节点的可用能力,在节点心跳报文中夹带节点的可用能力。由节点可用能力与路由距离综合选择服务节点,性能好的节点会负担多一点的任务,性能弱的节点会负担少一点的任务。在Peersim仿真平台下,对本地域内Peer节点负载均衡算法——改进的多次尝试请求算法进行了仿真实验及性能分析,对本地域外Peer节点负载均衡算法——改进的CDN-PR算法进行仿真实验及性能分析。仿真实验验证了改进的两个Peer节点负载均衡算法略优于未改进前的算法。更多还原

【Abstract】 The hybrid CDN and P2P network make a better network scalability, adaptability and robustness. The hybrid network provided service quality assurance for the distribution of large-scale heterogeneous network environment users and save server overhead as much as possible. Peer node load balancing is one of the key factors impact on the hybrid CDN and P2P network. The Peer node load balancing, mainly solve the query load imbalance problems.The existing load balancing algorithms caused by Peer node unbalanced requests, they are algorithm based on replication technology、algorithm based on rumor propagation、algorithm based on the awareness of the routing、algorithm based on the virtual node. Studied the replica placement; Replication algorithms based on the assumption—the future requests will come from the position of the elapsed requests, it lacks theoretical support.Load balancing of outside local area Peer node algorithm– Improve the CDN-PR replica algorithm. Improve the CDN-PR algorithm is because it makes an assumption that the future requests will come from the position of the elapsed requests, this assumption is correct sometimes, however, it is incorrect sometimes. To support the theory, import the Markov model predicting the position of the future requests, and secondly because the CDN-PR replica algorithm is proper for the CDN Peer node load balancing; Markov forecast the future requests based on the right now state of regional trends, predict future requests in a particular area may happen, provided the basis for the replica position decision making.Load balancing of local area Peer node algorithm - Improve the request retries algorithm. The improved request retries algorithm compute the node capacity by the Markov Model. It bring the node capacity in the heart beat package. Use the node capacity and TTL select nodes. Node with good performance will service more requests, node with bad performance will service less requests.Under the Peersim simulation platform, make the simulation and performance analysis on the load balancing of outside local area Peer node algorithm - Improved the CDN-PR replica algorithm. Make the simulation and performance analysis on the load balancing of local area Peer node algorithm - Improved request retries algorithm. The simulation reveal that both of the improved algorithm performance much better than the algorithm which is not improved.更多还原