Research On Key Technology Of Network Monitoring In SDN

In the increasingly complex network structure,the growing size of the case,the traditional network technology in the management and expansion has been stretched,people on the network performance requirements also increased.In this case,a new network architecture--Software Defined Network came into being.It will be the traditional network control plane and data forwarding surface decoupling to achieve a real network control and data forwarding separation.It is important to master the network performance parameters,manage the network topology and the running status of the link to the normal operation of the network.Aiming at the problem of obtaining link delay,topology management and link fault diagnosis in Software-Defined Network architecture,the research on measuring link delay,optimizing topology management and diagnosing link faults through network measurement is carried out.The main work of this paper is as follows:(1)A method for delay detection of SDN network based on LLDP protocol is proposed.First,a TLV field is added to the LLDP packet to record the timestamp.The LLDP packet is transmitted in the network and combined with the Echo message function in the OpenFlow protocol.Then,the delay information between the links in the whole network is measured while the controller makes the link discovery.The experimental results show that the link delay measurement method can measure the dynamic change of network delay,and can adapt to the sudden change of some links in the process of network operation,and has good practical application value.(2)A new method of SDN network topology management based on minimum point coverage set is proposed.The purpose is to manage the network topology with minimal network overhead.Firstly,the topology of the whole network is obtained through the network topology management module in the controller,abstracted and simplified into undirected graphs.Based on the idea of greedy algorithm proposed in this paper,we add a certain strategy to ensure the minimum vertex coverage The sum of the minimum degrees is the smallest.Using this method to calculate the network topology,get the minimum point coverage of the topology.Through the management of these nodes to achieve the purpose of the entire network topology management.The experimental results show that,in the case of reducing the sending and receiving of LLDP packets,the network topology management method proposed in this paper can achieve the purpose of topology management for the whole network.(3)A fault diagnosis method of SDN network link based on network measurement is proposed.From the network link delay and available bandwidth of the two angles in the network operation of the network link in the operation of the situation to diagnose,you can make the controller in time to find the network may be faulty links,take appropriate measures to ensure that the network normal operation.In the course of experiment,we first verify the availability of the available bandwidth of the link by polling the switch port counter,and then verify the delay and available bandwidth of the link and diagnose the validity of the link fault through the network measurement.