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ADMINISTERING CISCO QoS IP NETWORKS - CHAPTER 12

Multiprotocol Label Switching (MPLS) Multiprotocol Label Switching được thiết kế để chuyển tiếp các gói tin thông qua mạng lưới với hiệu suất rất cao bằng cách thêm một nhãn cho các gói dữ liệu khi họ vào mạng lưới tại các bộ định tuyến biên. Thông thường, mỗi bộ định tuyến dọc theo đường dẫn của gói tin tại mỗi phần cá nhân của tiêu đề IP. Tuy nhiên, kể từ khi MPLS áp dụng một nhãn hiệu khá đơn giản cho mỗi gói tin mà bao gồm tất cả các thông tin cần thiết gói tin tuyến đường. | Chapter 12 Multiprotocol Label Switching MPLS Solutions in this chapter Understanding MPLS Integrating MPLS into QoS Standardizing MPLS for Maximum Efficiency Controlling MPLS Traffic Using Traffic Engineering Integrating MPLS and Virtual Private Networking VPN 457 458 Chapter 12 Multiprotocol Label Switching MPLS Introduction Multiprotocol Label Switching is designed to forward packets through a network with extremely high performance by adding a label to packets as they enter the network at edge routers. Normally every router along the packet s path looks at each individual piece of the IP header. However since MPLS applies a fairly simple label to each packet that includes all of the information needed to route the packet the overhead created by each router looking through the packet s header is greatly reduced and the packet forwarding capabilities of each router are enhanced. This chapter unlike earlier chapters both introduces MPLS and shows some configuration examples. Since the basic theory of MPLS is fairly simple separate chapters are not required to discuss theory and implementation. Relatively speaking MPLS is a new technology and there are many enhancements such as the capability to use RSVP with MPLS to request labels that are being developed but are not yet fully deployable. This chapter focuses on the current RFCs pertaining to MPLS and does not discuss features that may not make it to full implementation. Understanding MPLS MPLS is the standardized version of Cisco Systems Tag Switching technology that integrates the flexibility and scalability of Layer 3 routing with the high performance and traffic-engineering capabilities of Layer 2 switching. MPLS is based on the concept of label swapping in which packets or cells are assigned short fixed-length labels that tell high-speed switching nodes how data should be forwarded. The key to understanding MPLS is to first identify the roles of each MPLS component.The main components are listed below and you