Management And Application Of Traffic Control On Linux Gateway

The quality of service(QoS:Quality of Service) concerns to the performance parameters that are of concern to the user. Since other technologies like ATM provide end-to-end QoS. The need for such a service in IP was appreciated. Quality of Service refers to the capability of a network to provide more reliable service. The primary goal of QoS is to provide priority including dedicated bandwidth, controlled jitter, latency, and improved loss characteristics. QoS technologies that are used in the design of extendable IP networks now are absolutely necessary. QoS provisioning in the internet using IP has been a topic of active research in the last few years.Various approaches have been suggested for provisioning QoS in IP networks.In this artical,it provides an overview of emerging QoS technologies that are currently being introduced and tested in Internet networks and that might be useful for next generation networks,such as Integreted Services Model,differentiated Services Model,MultiProtocol Lable Switch(MPLS)and Subnet Bandwidth Management(SBM). The Integrated Services (IntServ) model is characterized by hop-by-hop resource reservation and offers three service classes: guaranteed ,predictive (controlled-load) and Best Effort service. The guaranteed service is used for applications requiring fixed delay bound, while predictive service is used for applications requiring probabilistic delay bounds. The Resource Reservation Protocol (RSVP) is a signaling protocol for setting up end-to-end paths and reserving resources along them. Integrated Services together with RSVP signaling provide dynamic admission control, end-to-end predictable services and an efficient use of network resources. In the Differentiated Servcices (DiffServ) scheme, packets are marked differently to create several packet classes of different forwarding priorities. DiffServ is significantly different from IntServ, since in DiffServ, there are only a limited number of service classes indicated by the DS field. The amount of state information is only proportional to the number of classes rather than the number of flows. Therefore, DiffServ is more scalable. Also, it is much easier to implement and deploy DiffServ since sophisticated classification, marking, policing and shaping operations are only needed at the network boundary. In a typical implementation of Expedited Forwarding (EF), traffic conditioning including shaping, policing and packet marking is performed at the edge of an ISP network, while core routers mainly need to support priority scheduling. Many researchers have adopted openness and expansion of Linux itself as their experiment platform .Linux has support for QoS. A detailed study of Linux QoS Support was done. The latest Linux kernels offer good support for QoS , the QoS function module of Linux is called Traffic Control(TC).TC encompasses the sets of mechanisms and operations by which packets are queued for transmission/reception on a network interface. The operations include enqueuing, policing, classifying, scheduling, shaping and dropping. TC supports various kinds of queues. The queues supported currently include Class Based Queues (CBQ), Token Bucket Flows (TBFs), priority queues, Random Early Drop (RED), DSMARK etc. In this article, it provides an introduction and overview of the capabilities and implementation of traffic control under Linux.First,it describes the design and realization of QoS module, and the default queueing discipline , pfifo_fast_ops. Next,it describes how to use TC, how to use the CBQ (Class Based Queue) queueing discipline and the spliter based route. What TC can do for us , throttle bandwidth for certain computers,throttle bandwidth to certain computers,help us to fairly share our bandwidth. With Linux QoS moduel, it is possible to make very flexible traffic control.But,currently, not many people are using these advanced features. This is for several reasons. While the provided documentation is verbose, it is not very hands-on. Traffic control is almost undocumented.Using TC, we can class and manage traffic and throttle the bandwidth. But, because of the complexity of TC, and the lack of document, it restricts the use of TC. A good user interface is required to be able to set the QoS options from the user space. In this project,it use a QoS mechanism that Linux Kernal provided――TC to emplement an application that offer a user friendly interface on Linux gateway.It makes managers conveniently control the bandwidth without the study about TC. At this time,managers can use the...