The Research On Load Balance Of A Multiple Export Gateway

With the increasing of bandwidth requirement and showing concern for the network security,more and more enterprises install multiple access links for fault tolerance and the aggregate bandwidth and improving the overall availability and security of the Internet connectivity.When the access links are subscribed from different ISPs,this approach is called multi-export.The key enabling technology for multi-export gateway is link load balancing,which spreads an enterprise's Internet traffic among multiple access links to increase the aggregate thoughput,and diverts traffic away from non-functional links when fail.Although there exist several commercial multi-export load balancing products in the marketplace,its expensive price,middle and small enterprises can not afford it.There must be some inexpensive and applied schemes of link load balancing.For this reason,we present a load balancing scheme based on Linux.Thanks to Linux is an open-source operation system,with its steady routing and netfilter technology,we can config a normal server with Linux as a multi-export gateway. Because of its inexpensive cost and maneuverability,it is fit for mid-small enterprises to build their own link load balancing systems.In this paper,we take apart of the basic structure of multi-export load balancing systems,discuss the tradeoffs involved in load balancing and fail-over implementation strategies,analyses the link load balancing and link failure protection strategies of implementation Mechanism,and according to the flow of Intranet link,with the existing load balancing algorithms,we present the improvement of Weighted Least-Connection scheduling(WLC) algorithm—Based on NAT WLC algorithm.And we build the antitype,simulation and comparative experiments shows,the improved algorithm is suitable for the balance of traffic flow, get better the congestion of export control and improve the QoS of access router. Combined with the current widespread use of policy routing,we present the projects combined the policy routing with based on NAT WLC,which come true the load balancing of multi-port gateway,the differential services of part of users,and the function of protecting the links.This paper also presents the link load balancing and link fail-over protect tests.The tests show that the Linux-based load balancing schemes speed up the accesses of internal users to Internet servers and the accesses of lnternet users to internal servers. improves the link availability.Though using of link protect,improves the link reliability.