Research And Application Of MPLS VPN Based On QoS

Recently, with the development of Internet, various services have been gradually accepted by people, especially the rapid development of real-time services, which demand service providers to provide safe and reliable quality of service. As people constantly study the QoS technology, it attracts more and more attention, which is based on MPLS VPN.The QoS technology contains two types of structures: one is the model of IntServ (Integrated Service); the other is the model of DiffServ (Differentiated Services). This paper mainly researches the model of DiffServ QoS based on MPLS VPN. The concrete contents are as follows:First, this paper simply introduces the technology of IP VPN and three types of key technologies of VPN network. According to the application of services, realization way, and network model, there are different kinds of VPN network. The MPLS technology combined with the advantages of IP technology and ATM technology is the main carrier technology of the next generation broadband core network data service. Besides, this paper expounds in detail the working principles of MPLS technology, and there is an example of packet forwarding, which makes us deepen understanding the MPLS technology. In the process of establishing MPLS network, the LDP (Label Distribution Protocol) protocol is very important, which contains four stages: the discovery of LSP (Label Switching Path), the establishment and maintains of LDP session, the establishment and maintains of LSP, and the revocation of LDP session. Combined with the routing function of the third layer and the traditional and rapid forwarding mechanism of the second layer in IP network,the MPLS technology supplies very good solution schemes for QoS and VPN applications. MPLS L3VPN (Layer 3 VPN) is the master technology of MPLS network, so this paper introduces in detail the process of releasing routing information and different kinds of network schemes of MPLS L3 VPN network.Second, this article proposes that the DiffServ model is more beneficial to solve the QoS problem in MPLS network according to the comparison result between DiffServ model and IntServ model. Based on the realization of DiffServ model in MPLS network and the different producing way of the PHB (Per-Hop-Behavior), the model can be divided into two types: E-LSP (EXP-LSP) and L-LSP (Label-LSP). Based on the working principle of MPLS VPN and the working mechanism of QoS, it proposes an implementation model for QoS in MPLS VPN. The model extends the LDP protocol and adds DiffServ TLV function. It is convenient to offer different QoS strategies to user for operation business. In the light of many users in MPLS VPN network and limited interface of PE, the author puts forward an extended model-HoVPN (Hierarchy of VPN). The implementation principle of this model is that using several PEs corporate works instead of one PE traditional function. In the aspect of identification of faulty links in MPLS VPN, the BFD (Bidirectional Forwarding Detection) fast testing mechanism which is different from LSP ping is presented. In this paper, establishing BFD session in LSP path and BFD packet detecting and path restoration are explained in detail.Finally, the author takes use of the simulator based on a software development platform in some communication company in Hangzhou to test QoS model in MPLS VPN. Through specific configuration on each facility in MPLS VPN, the network's connectivity is realized. According to testing the packet loss rate of flow in MPLS VPN under different DSCP value, it is proved that the technical scheme of QoS model in MPLS VPN based on DiffServ is feasible and effective.