In order to simulate different general arrival processes, describe and monitor flow exchange between the controller and the switches we presented the SDN as queuing system. Operations on SDN switches with different data transmission processes control capabilities lead to a significant delay change for flow entries configuration. In this paper is introduced an analytical and simulation analysis of an SDN model where the network is modelled as queueing system to capture the time costs associated with the controller and the switches activities. The rule in the switch is set only for the first packet, and then all the other packets of the flow use it. Controller creates appropriate rule and sends packet back to switch (packet out) for processing. Packets which have no match are sent to the controller (packet in). Data management in OpenFlow is carried out, not on the individual packet level, but at the level of their packet streams. Each flow table in the switch contains a set of flow entries each flow entry consists of match fields, counters, and a set of instructions to apply to matching packets. Each switch must contain one or more flow tables and group tables, which perform packet lookups and forwarding, and support OpenFlow secured channel to a remote controller. According to OpenFlow standard specifications, the interaction between the controller and the switch is carried out through OpenFlow protocol. OpenFlow is an open standard, which describes the remote management requirements to a switch that supports OpenFlow protocol. The idea of creating a unified, independent from the network equipment manufacturer, program-controlled interface between the controller and the network transport infrastructure is defined in the OpenFlow standards and OpenFlow protocol, which allows users to define and control with whom, under what conditions and with what quality can interact on the network.
Each controller has at least one application that manipulates switches connected to it, and can provide a global view of physical network topology under the controller management. The controller can manage one or several OpenFlow switches it contains a network operating system that provides network services for low-level network management, network segments, and the state of network elements and applications, implementing a high-level network management and data flow. However, all these benefits come with a non-negligible problem in network functionality such as packet transmission rate and network performance, which are attributed to the use of the controller as a remote system to manage all transmission network devices (switches). This simplifies the network usability and significantly reduces the network system cost and equipment.
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The concept of software defined networks (SDN) is a growing trend in the domain of telecommunication network management, that offers to remove restrictions on existing infrastructure networks by dividing the network control plane and data plane by means of transferring control functions of network forwarding devices (routers, switches) in the applications running on a single entity (controller), which makes the network more centralized and improves its software management capabilities.
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