As current networks expose more and more disadvantages and people have higher and higher requirements on network performances, researchers have to add many complex functions to a system architecture of a routers, for example, Open Shortest Path First (OSPF), Border Gateway Protocol (BGP), multicast, differentiated service, traffic engineering, Network Address Translation (NAT), firewall, Multi Protocol Label Switching (MPLS), and so on. Consequently, a switching device such as router becomes more and more bloated and a performance improvement space becomes smaller and smaller.
However, totally different from a dilemma of a network field, a computer field gets a rapid development. With a careful review of a development of the computer field, it is not difficult to find that the key lies in that the computer field finds a simple and useful hardware underlayer (x86 instruction set). Due to such a public hardware underlayer, in a software aspect, both applications and operating systems get rapid developments. At present, many people advocating to redesign a computer network system architecture think that: network can solve all problems currently confronted by a network by copying a success of the computer field. Under a guide of this idea, further network likes this: underlying data paths such as switch and router are “mute, simple and minimum”, a public open Application Programming Interface (API) is defined, and meanwhile a controller is adopted to control the whole network. Future researchers freely call a underlying API on the controller to program so as to realize an innovation of network.
Based on the above theory, a Software Defined Network (SDN) appears. The SDN provides users with a more accurate and personalized customization means for network by taking an open programmable interface and control-forwarding separation as main features, has a broad application prospect at the cloud computation data centre, the edge access field even the network core node, and will certainly have a deep influence on a network development direction of next decades.
In recent years, an SDN technology represented by Openflow receives widespread and enthusiastic concerns. A main feature of the Openflow is a separation of a control plane and a forwarding plane. The control plane is moved up to a controller running on a server. Network devices reserve a forwarding function, and control information is transmitted through an Openflow protocol between the control plane and the forwarding plane to instruct forwarding behaviors of the network devices. The Openflow protocol allows users to obtain means for more directly controlling the forwarding behaviors of devices, but also brings many problems. These problems mainly includes that: one, a control-forwarding separation architecture is not beneficial for orderly evolution of traditional network devices, and two, there is no special Openflow chip, flow table information needs soft unlock and thus influences effective speeds of flow tables. Based on the above problems, Internet Engineering Task Force (IETF) proposes a concept of opening an Interface to the Routing System (I2RS), which solves a problem of traditional network devices orderly evolving to the SDN by opening an interface of a routing system on the control plane.
FIG. 1 is a structural block diagram of an I2R2 system in the related art. As shown in FIG. 1, a core idea is to open an interface to communicate with at least one external control client on a basis of a routing-forwarding system of a present traditional network device. The at least one external control Client dynamically sends routing status, policy and so on to each agent through events, topology change, traffic statistic and other information fed back by devices. The same as traditional configuration management ideas, a routing-forwarding system on a device generally does not distinguish routing status and policy of home control clients. However, this mode is not beneficial for an accurate management of a management layer.
In view of the problem that at least one of routing status and policy information of home control clients are not distinguished in the related art, an effective solution has not been provided yet.