Research On SDN-based Segment Routing Technology

With the rapid development of network informatization,the requirements for network services are also increasing.Network operators expect to implement more stringent Service Level Agreements(SLAs).However,traditional IP networks lack the flexibility and scalability properties,at the same time,operators need to be further simplified for the maintenance and operation of the network in order to achieve the optimal use of network resources.Segment Routing(SR)is a new type of network architecture that implements the source routing mechanism.It expresses the path explicitly by pushing a sequence of segment lists consisting of a series of segments into a packet header,and uses the segment to guide the flow forwarding.With the rise of Software Defined Networking(SDN),SR technology can be perfectly combined with SDN to make it easier and more efficient to solve network problems.This thesis mainly studies several common application scenarios of SR: SR-based Fast Rerouting,using SR to plan network Traffic Engineering and combining SR to implement Service Function Chain.The traditional fast rerouting scheme always has various problems.Using fast rerouting of the SR not only can achieve 100% failure coverage of the network,but also does not require additional protocols and simplifies network operations.In the single link failure scenarios,this thesis proposes next-hop-based SR fast rerouting.By using the segment to guide service flow forwarding,Link loops can be effectively avoided during the recovery process,while reducing the length of the recovery path.In the multi-link failure scenario,this thesis proposes flow-divergence-based SR fast rerouting to effectively avoid link congestion that may be caused by centralized recovery of affected flows.Using SR for network traffic engineering,it uses the SDN's centralized control features,real-time control of network traffic status,and active forwarding of traffic through the SR segment to achieve optimal network traffic engineering.In this thesis,SRbased traffic engineering is proposed.Traffic headers are pushed into different segment lists for traffic distribution to guide traffic along different paths to reach destinations.This prevents links from being congested due to centralized traffic forwarding and minimizes link maximum utilization.The Service Function Chain is composed of a series of ordered virtual network functions(VNFs).For network services,these service functions need to be implemented,and SR provides a similar architecture to consider the application of SR to implement SFC.This thesis proposes an SR-based service function chain implementation scheme.The SR segment is used to represent the VNF of the SFC and the mutual mapping between the both is implemented.The active segment of the segment list is used to guide the services to the corresponding node server in an orderly manner with functional processing.The verification results show that the solution can further optimize the network packet overhead and effectively reduce the depth of the segment list.