Research And Implementation Of Link Failure Recovery Technology Based On SDN

Although the centralized control of SDN has achieved very rapid development at present,due to congestion of critical links,uneven utilization of bandwidth,failure of links or network nodes,etc.,the reliability of SDN networks has become a difficult prob-lem for network practitioners.When performing link failure recovery at the data plane,it usually includes two types of recovery strategies:proactive and reactive.The reactive recovery scheme has a long recovery time,and it is difficult to meet the carrier-grade requirements that the network should recover within 50 ms.However,as the current mainstream of data-plane link failure recovery solutions,proactive recovery scheme also have some inherent deficiencies,such as excessive resource consumption of flow entries and possible link congestion after fault recovery.Since the flow entries of the backup path need to be installed on switches in ad-vance,the proactive recovery scheme consumes a lot of extra flow entry resources.Aiming at the problem of excessive consumption of flow entries in proactive recovery scheme,this paper proposes an proactive link failure recovery strategy based on segment routing(SR-PLFR).The SR-PLFR scheme uses segment routing to encapsulate the link information of the routing path into packet header at the ingress switch via the MPLS label,and the other intermediate switches in the path directly perform packet forward-ing based on the MPLS label,without the need to scan and match flow entries based on the other feature information in the packet header.Such operations can effectively re-alize flow aggregation,thereby reducing the flow entry resources consumed by the core switches.Compared with previous proactive recovery scheme CAFFE,the SR-PLFR scheme outperforms by about 21.5%on the average flow entries consumption.Due to the uncertainty of network traffic,it is difficult to ensure that the backup path determined in advance in proactive recovery scheme can always meet the transmission requirements of interrupted traffic.Aiming at the link congestion problem that may oc-cur after recovering in proactive recovery scheme,this paper proposes an proactive link failure recovery strategy based on congestion avoidance(CA-PLFR).In the CA-PLFR scheme,the backup path of the protected link no longer remains unchanged,instead,it will be dynamically updated in order to achieve link load balancing after fault recov-ery.In order to achieve the purpose of congestion avoidance,the CA-PLFR scheme will use the historical link load and the support vector regression prediction model to make predictions on the link load of the next cycle,and adjust the backup path based on the prediction results when updating the backup path.Compared with the SR-PLFR scheme where the backup path remains unchanged,the maximum link utilization in CA-PLFR is reduced by about 27%,and the average link utilization is also reduced by about 7%.