The Research And Implementation Of Multihoming Link Load Balancing Based On Linux

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 multihoming.The key enabling technology for multihoming is link load balancing,which spreads an enterprise's Internet traffic among multiple access links to increase the aggregate thoughput ,and diberts traffic away from non-functional links when fail.Although there exist several comercial multihoming load balancing products in the marketplace,very little is published about the design tradeoffs and their implications,but also 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 linux-based load balancing scheme. In this paper,we describe the design space of multihoming load balancing systems,discuss the tradeoffs involved in load balancing and fail-voer implementation strategies, and present outbound traffic load balancing and inbound traffic load balancing. For outbound traffic.using policy routing technology in linux to assign traffic to multiple access links,then execute source NAT and forward the traffics.There are three load balancing methods have been implemented:Destination address-based load balancing, Source address-based load balancing and network application-based load balancing.For inbound traffic,using dynamic DNS to redirect the incoming traffic to different links,then execute destination NAT and forward the traffic to internal servers.This paper also present the link load balancing and link fail-voer 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 internet users to internal servers,improves the link availability.Though using of link protect,improves the link reliability.Aslo Linux is an open-source operation system,with its steady routing and netfilter technology,we can config a normal server with linux as a multihoming gateway.Because of its inexpensive cost and maneuverability,it is fit for mid-small enterprices to bulid their own link load balancing systems.