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IntroductionCloud computing revolutionized the online availability of on-demand computingresources such as data storage, especially Computing powers, etc. Cloudcomputing is considered a Software as a service (SAAS), Platforms as a service(PAAS), and Infrastructure as a service. SAAS provides software resources fordevelopers, whereas (PAAS) provides the platform services on clouds and (IAAS)delivers the most central VM servers and related Infrastructure utilizes by cloudcustomers. To provides all these services, providers maintain and manage largescale data centers where thousands of host servers are connected through numerousnetwork switches.For decades, Cloud computing services are managed by service providerstraditionally, where the data centers require high administration. This can be verycostly and time consuming from your business point of view. Due to theheterogeneity in resources, these cloud-based platforms become more complexwhile management and many other issues were also arising.To deal with all shortcomings of traditional cloud computing, software-definednetworking (SDN) concept is adopted by data cloud centers. Software-definednetworking (SDN) concept is a network architecture used to manage the networkthrough centralized control and programmed intelligentially using softwareapplications . SDN manages or controls the network flow efficiently because thesoftware controller observes the whole network and makes decisions more quicklythan traditional networks.In addition to these major concepts of cloud computing and SDN used with cloudcomputing, many other concepts like network virtualization, network layers, SDNenabled cloud computing, SDN impact, and future directions will be discussedbelow.Related workThere are various criteria set for networking that requires to be followed . Thereare different networking basic bodies; some of them are International Organizationfor Standardization (ISO), International Telegraph and Telephone ConsultativeCommittee (CCITT), and so on... OSI model layers are the following:
The first layer is defined as a physical layer that sends and receivespackets.The data link layer uses logical link control and media access control.The third layer is the network layer, which receives packets by using IPprotocols.The fourth layer is the transport layer, which uses TCP protocols.The fifth layer is a session layer that is used for authentication andauthorization.The sixth layer is a presentation layer for WWW and (HTTP).The seventh layer is an application that interacts with the applicationthrough GUI.In the early stages of cloud computing, service providers manage cloud datacenters, which consisted of thousands of host servers requiring high administrationin managing the data centers. Due to this fatiguing task's complexities, providersfaced numerous problems while providing different types of cloud services tousers. In the traditional network approach in cloud computing, the control plane isused over or on top of forwarded planes. The decision-making process is done byeach of the switches in the network according to the information he gathers fromits neighbor devices in a distributed state. As each device makes the network'sdecision, this can increase the complexity and bring unpredictability in thenetwork.On the other hand, SDN provides centralized control into a software controller andobserve the network entirely. As the information is gathered centrally, thecontroller can easily decide according to the situation. Providers can easilyprogram control logic into the controller and send these packets to networkswitches in the entire network through SDN protocols. Any control login will bedesigned and implemented into the SDN as shown below in figure 1 .
Figure 1The world of cloud computing has acknowledged SDN as the mostadvantageous software in cloud computing due to its helpful features likeeasily programmable control planes, security enhancements, frequentlychanging workloads, etc. The basic technologies used to develop the SDNenabled cloud computing are the virtualization of servers, SDN, and virtualmiddleboxes, which are like the network appliances like firewalls to filter,transform and maintain the packet forwarding. Moreover, OpenFlowprovides us the interface to cache the packet forwarding in switch tables andnotification for topology change.SDN architecture is based on cloud managers, centralized SDN controller,East-west APIs, cloud resources, hypervisors, resource managementswitches, and SDN controllers, etc. All these components of SDNarchitecture are managed the data cloud centers (DCN) collaboratively asshown in figure 2 .