Research On Delay In The Application Of DS-TE Technology In MPLS VPN

It’s the most important in the technology of MPLS that introducing the concept andapplication of labels.In traditional IP communication mode if the address of receiver iswanted to be known unpacking in the third layer is necessary,which will be slower than theMPLS based on the label.MPLS is a safer communication technology because theexistance of label make the unpacking in the third layer unnecessary.Therefore, given tothe time effectiveness and safety features, the backbone network based on MPLS is verysuitable for applications in VPN technology. MPLS is mainly maked up of CE、PE、P.CEprovides user of VPN the access of the network.PE which directly connected with the CEprovedes has the function of LER in MPLS network and create a virtual route forwa rdingtable for every customer.P has the function of LSR in MPLS network and completes thetask of fast-forwarding and control.DS-TE technology is a set of differentiated service model and traffic engineeringmodel.In the differentiated service model packets is divided into different priorities,whichare reflected in the TOS field.The TOS field is made up of6bits and has12levels whosehighest level is CS7(111000) and lowest level is0(0). when a packet of differentiatedservice model is received in MPLS VPN network PE will transformate PHB as EXP in thelabel and make sure its priority.Different priorities will use different levels of LSP.Trafficengineering make the bandwidth resources not wasted by a lot of LSPs which have a samelevel.Traffic engineering in MPLS technology has four parts that are packet forwardingpart、information distribution part、path computation part and signal component part.As issaid above Traffic engineering can largely reduce the case of congestion in the MPLS VPNnetwork.DS-TE is a protection technology that not only satisfy the need of customer butalso avoid resource wastage.BH-PREPT algorithm is to solve the problem of bandwidth wasted.The formulas and principles of algorithm is based on bandwidth utilization.As the development of fibercommunication customers mostly have a very rich resource of communication bandwidthand the price of VPN service has gradually been made lower.Therefore, the availablebandwidth resource used by the enterprise user is no longer the main limit ofcommunication service quality.The disadvantage of BH-PREPT algorithm that in terms ofavoiding cascading has better performance is pay too much attention to the waste ofbandwidth caused by LSP preemption.LH-PREPT algorithm suggested by the author has both the advantage of aviodingcascading preemption and the least cost of priority preemption.Those advantages aremainly reflected in the delay characters.Author fixs the formulas of total cost based on theperformance and need of VPN business in the current communication network.Finally twocommunication scenarios are simulated by OPNET and get the result that delay in the VPNnetwork has been efficiently reduced.