The Design And Implementation Of Link Fault Detection Module Based On BFD Protocol

With the rapid development of the Internet,real-time services such as online chat,video on-demand,multi-user online games,and key services such as e-commerce are widely spread on the Internet.These services put forward higher requirements for the reliability of network devices,which need to be able to recover quickly from failures.In this case,Bidirectional Forwarding Detection(BFD)protocol has attracted the attention of many network equipment manufacturers.According to BFD protocol standard and market demand,a communication company proposed a link fault detection scheme based on BFD protocol to realize reliable and fast link fault detection mechanism.In this paper,the design and implementation of the link fault detection module based on BFD protocol adopts the top-down,layer-by-layer refinement structured program design method,and takes the BFD standard protocol document as the theoretical basis to realize a fast link fault detection function on Comware V7 network operating system.This paper analyzes the overall architecture of BFD module,designs the link fault detection module using distributed model.It discusses the relationship between link fault detection module as a new module in the network operating system and external module as well as the interaction between its internal components.And it maintains the independence between modules as far as possible.At the same time,the link fault detection module is divided into several small functions,such as BFD command configuration,session management,timer and packet sending and receiving.And these four main functions are designed and implemented.The link fault detection module was tested and analyzed.And the basic functions of the link fault detection module were verified by wireshark packet capture software to analyze the packet captured on link and create network faults artificially.By linkage test with other application protocols and comparing the speed of fault detection when BFD function is configured with that when BFD function is not configured,it is verified that the link fault detection module can meet the requirement of fault detection within 20 ms.Through the test to establish 12 K sessions,it verify that the link fault detection module can meet the requirements of establishing a large number of sessions.The link fault detection module based on BFD protocol implemented in this paper conforms to the BFD protocol standard and initial requirements.It meets the test standards of telecom operators and the performance requirements of establishing a large number of sessions.The link fault detection module based on BFD protocol is an important application on routers and switches,which effectively improves the availability and reliability of the whole network.