Simulation Of The Mpls Protocol And Qos

The Internet is growing at an amazing speed in recent years,it ISPs are challenged with rapidly improved network and new multi services. (Email,web surf,broad band , multimedia ,QoS etc) In 90's, ATM proved super excellent solution for performance and raffle engineering to ISP.And many carriers found it is very economical to implement Internet multi-service in ATM network.But ip-based network is becoming more prevalent each year, pure ATM based network is impossible in reality.In fact , today 's ATM network is used to carry IP based traffic.So people wish to combine IP traffic and ATM function in one network technology. MPLS progressed in the background. MPLS stands for "Multiprotocol Label Switching",it integrates the label-swapping paradigm with network-layer routingjt brings the TE(traffic engineering) of ATM to packet-based network and also it can run over nearly any transport medium (ATM, FR, Ethernet...) instead of being tired to a specific layer-2 encapsulation.As we know,the current default Internet assumes the "best-effort" service model .In this model the network allocates bandwidth among all of users at best it can and attempts to serve all of them without making any explicit commitement as to rate or any other service When congestion occurs.it can't provide QoS guarantee for different service classes. So many QoS mechanism was brought forward ,such as one traffic (or one class) based QoS technology-InteServ DiffServ ,and macrocosmic QoS guarantee -TE. RSVP is based on control signal which need save state information , it is more difficult than DiffServ. In Differentiated Service , it define a model for implementing scalable differentiation of QoS in the Internet .Packets are classified and marked,policed and shaped at edge of the network in order to receive a particular per-hop forwarding behaviour on nodes along their path.Per-flow state does not need to be maintained in the interior network nodes,thus leading to increased scalability.TE is the process of controlling how traffic flows through one's network so as to optimize resource utilization and network performance,in point of fact TE is a indirect QoS mechanism.Differentiated Servic(DiffServ) is scalable for deployment in today's Internet ,and Multiprotocol Lable Switching(MPLS) provides fast packet switching and the opportunity for traffic engineering.Thus,the combination of DiffServ and MPLS presents a very attractive strategy to backbone network providers.In fact ,MPLS is good at implementing QoS,such Diffserv,RSP and TE. This strengthen our confidence in its success.But, to our disappointment,it hasn't been implemented in ns,which is one of the most prevalent network simulator.To implement standard mpls fuction and diffserv in mpls are our major attention.In this paper,we will review the features , main components of MPLS and its QoS mechanism (such as InterServ,DiffServ,TE).And then we will describe the design and the implementation of MPLS Network Simulator,which supports the establishment of LSP as well as any other basic MPLS functions such as LDP and Label switching and various approaches which can be used to support differentiated services in MPLS environment and implement DiffServ+MPLS in ns.To verify the accuracy and efficiency of our implementation,two examples are simulated and evaluated.One is a simulation for basic MPLS functions .The other is a simulation for traffics with different QoS each other in MPLS network.