| With the rapid expansion of the scale of Internet, it has become an platform that acquire knowledge everyday, and with the development and maturity of network technology, it become more and more difficult to make some innovation testing based on the existing network equipment and protocols. It may also affect the normal data traffic during the test, which has become a major obstacle to the realization of new network protocols, but also makes a limited impact on the actual behavior of the network’s current innovation generated. OpenFlow is a new model of network switches based on SDN, its biggest superiority is loosely coupled between control plane and data plane, supports centralized network control and realization of the underlying network infrastructure for the upper application transparent. It’s easy to find from the name of SDN, it is extremely flexible software programmability. making automated management and control capabilities of the network was an unprecedented increasing, an effective solution to the current network resource constrained scale-facing systems, group net inflexible, difficult to quickly meet business needs and other issues.Despite years of development, OpenFlow has become one of the important South standard interface in the SDN domain, but it still faced with many problems and challenges.(1) Poor forwarding performance. It uses forwarding flow table in OpenFlow network to forward packets rather than the traditional network protocol stack. A flow table contains the traditional protocol stack from layer two, layer three and layer four protocol information that brings a lot the problem when data packets are forwarded through OpenFlow network. It need to match a lot of domain field while ensuring the flexibility of the network. While the flow table becomes heavy, the forwarding performance will delicate.(2) Scale of the flow table. In the conventional apparatus, each TCAM table matching using different field lengths, separate design, way to obtain the maximum capacity is set smaller overhead. In OpenFlow network, we no longer make any distinguish between matching fields. We use the maximum length of flow table instead and all entries using the maximum length of the stream. In OpenFlow1.0, the matching entries in the field is as long as252bit and traditional networks matching length is only60bit to80bit. After OpenFlow version1.0, Matching field has increased, making the flow table size increases day by day.In this paper, we make a further study for the existence of the problem in OpenFlow networks. Firstly, I do research on the packet parsing under OpenFlow software network switches and design a packet protocol analysis structure is proposed to accelerate packet parsing algorithm, packet parsing performance for OpenFlow switch software upgrade based on the structure. Secondly, I study on the structure of flow table of OpenFlow software switch, combined with OpenFlow protocol specification for multi-level flow meter designed and implemented a fast flow table matching model. The model is simplified by packets in a multi-stage flow table matching process in order to enhance the analytic from the packet to the packet forwarding rate of circulation. Finally, according to the characteristics of multi core platform, I propose a parallel implementation scheme of message analysis and flow meter rapid matching model software. As the experimental results shown, the improved model we proposed for data message in OpenFlow network forwarding performance improvement has great effect. |
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