Study On VPLS In Metro Ethernet Networks

Ethernet technology has been developing much faster than ever before. The ratification of ITU-T X.86 successfully introduces Ethernet into carrier grade telecom network for the first time, and another ITU-T standard, X.87, makes it feasible and reliable for Ethernet to carry multi-services in metropolitan area networks. In recent years, Ethernet has extended itself into metro area networks, becoming the optimal candidate in building metro. Among the many metro-building candidates, VPLS is highly praised for its simplicity, reliability and ease of implementation. It takes the advantages of IP/MPLS backbone to provide customers with an emulated LAN; upon it transparent LAN services can be easily carried out.A VPLS network model and its implementation is first put forward. By building a full-mesh of pseudo-wires between PE nodes and mapping traffic onto MPLS LSP tunnels, VPLS carries different kinds of services for customers. Then it studies the mechanisms for building and managing FIB table, etc. It also describes the architecture for implementing multi-layer VPLS routing and switching platform. Through experiment it concludes that the theoretical model introduced is practical and feasible.A VPLS model for traffic engineering is proposed for the purpose of end-to-end QoS guaranteed packet switching. It points out the complexity when offering customers with SLA services. Some important technical issues, such as the traffic pre-treatment on CE nodes, what steps PE nodes should take when receiving traffic from UNI, including frames coloring, UNI broadcast storm control, etc., are fully addressed. The last issue is the hose model based bandwidth guarantee, in which it illustrates how VPLS feasible tree can be implemented to realize the multipoint-to-multipoint dynamic bandwidth allocation, and how backup path can be computed when link failure occurs in a VPLS feasible tree.A delay-constraint point-to-multipoint forwarding algorithm is proposed to avoid too much flooding in VPLS network. Flooding, if not properly handled, often degrades network performance and wastes resources. With real-time services taken into account, a delay-constraint point-to-multipoint routing mechanism is described through P2MP MPLS LSPs. As complementary, it briefly illustrates how to establish P2MP LSPs,concluding that the proposal can be feasibly implemented.A shared aggregate multicast tree is suggested for multicast services in VPLS. As VPLS is based on"distributed"switching architecture, how to learn multicast membership and how to distribute them among PE nodes are the greatest challenges. It describes both IGMP snooping and PIM snooping to learn multicast membership, and discusses the conflict between multicast states and bandwidth efficiency with shared aggregate multicast trees as an optimized trade-off solution. Through the mapping mechanism between multicast groups and aggregate trees, the overhead for multicast state maintenance can be greatly reduced.