分布式Web服务器中负载均衡的实现

实现和测试了一种可扩展的分布式Web服务器原型。原型由多台接收和处理TCP连接的服务器通过负载均衡集群而成，主机IP地址利用Round Robin DNS发布，任意主机都可以接收客户端的请求。一旦当客户试图建立连接，主机要决定接收连接提供服务还是重定向连接到其它主机。每台主机保持集群定期组播的系统负载信息，并利用低负荷的IP封装IP技术重构数据包来重定向请求。性能测试表明这种技术比RR—DNS具有更好的性能，而且利用系统负载状态的重定向连接比无状态的重定向效果更好。

Implementation of Load Balancing in Distributed Web Server

An implementation of a prototype scalable Web server is presented and evaluated in this paper. The prototype consists of a load-balanced cluster of hosts that collectively accept and service TCP connections. The host IP addresses are advertised using the Round Robin DNS technique, allowing any host to receive requests from any client. Once a client attempts to establish a TCP connection with one of the hosts, a decision is made as to whether or not the connection should be redirected to a different host. The low-overhead IP is used encapsulation within IP is used to redirect TCP connections. Each host keeps load information about the remaining hosts in the system, which is maintained using periodic multicast amongst the cluster hosts. Performance measurements suggest that the redirection using system state outperforms both pure RR-DNS and the stateless.