Flood attacks are among the most devastating distributed denial of service (DDoS) attacks. In these attacks, attackers try to use up resources by sending massive floods of packets in order to seriously challenge the provision of services. Hierarchical architecture and numerous weaknesses in the structure of communication protocols in conventional networks lead to the fact that firewalls cannot provide an integrated and effective mechanism against these attacks. With the emergence of Software Defined networking (SDN), there are new prospects for solving structural and security problems in Traditional networks. In this paper, a heterogeneous method proposed based on cooperation between traditional service provider and software-based controller (SDN) to deal with flooding attacks. In this method, the attack detection module is located in servers and the call module is located in controller(SDN). In order to simulate the heterogeneous method the MiniNet emulator is used in combination with the Pox controller. Next, the simulated model is evaluated and it is finally concluded that besides protecting against attacks in conventional networks, the proposed method provides other benefits including the extent of computational load and the response time compared to other Software Defined methods.

The current architecture of data center networks is a combination of Ethernet switches and routers. However, this architecture cannot satisfy the requirements of these networks. Ethernet switches are flexible, have simple configuration, but are not scalable. Routers provide better scalability and efficient use of bandwidth, but are costly. This architecture has a noticeable overhead configuration and maintenance. So, if we had a larger Layer 2 networks, number of routers and consequently the costs will be lessened. Many methods are presented for this purpose.In this paper introduce some main requirement center data networking and characteristic of proposed methods. Among of these methods, OpenFlow is preferred.But the control overhead of OpenFlow is high. One way to reduce the control overhead by separating big and small flows and letting the controller to control only the big flows. ECMP routing is a method that can be used for routing small flows. However OpenFlow does not support ECMP. In this paper, a new method based on OpenFlow is proposed to replace ECMP. The proposed method can achieve performance comparable to ECMP.

The significant impact of information and communication technology (ICT) on Greenhouse Gas emissions has caused a considerable research interest in energy management of network devices in recent years. As the amount of power consumption in routers and switches is a function of their working frequency, one approach to energy saving is to adapt working frequency of such devices dynamically and proportional to their traffic load. This paper describes this approach in Software Defined Networking (SDN) framework by proposing a Mixed Integer Linear Programming (MILP) formulation for a network of FPGA based interconnected OpenFlow switches. The prerequisite information of switch power profile is obtained by running experimental tests. The proposed method is applied to an infrastructural dataset extracted from the standard SNDlib database. Simulation results show that frequency scaling technique reduces power consumption by more than 37% in comparison to other well-known power-saving approaches.

Software-defined network (SDN) is the next generation of network architecture thatby separating the data plane and the control plane enables centralized control with the aim of improving network management and compatibility. However, due to the centralized control policy, this type of network is prone to Inaccessibility of control plane against a denial of service (DoS) attack. In the reactive mode, a significant increase in events due to the entry of new flows into the network puts a lot of pressure on the control plane. Also, the presence of recurring events such as the collection of statistical information from the network, which severely interferes with the basic functionality of the control plane, can greatly affect the efficiency of the control plane. To resist attack and prevent network paralysis, this paper introduces a new architecture called SAHAR, which consists of a control box consisting of a coordinator controller, a primary flow setup controller, and one or more (as needed) secondary flow setup controller(s). Assigning monitoring and managing tasks to the coordinator controller reduces the load of flow setup controllers. In addition, dividing the incoming traffic between the flow setup controllers by the coordinator controller distributes the load at the control plane. Thus, by assigning the traffic load resulting from a denial-of-service attack to one or more secondary flow setup controller(s), the SAHAR architecture can prevent the primary flow setup controller from impairment and resist DoS attacks. Tests show that SAHAR performs better in the face of a DoS attack than existing solutions.

Software-Defined Network (SDN) introduces centralized network control via the OpenFlow protocol, enhancing network management, traffic routing, and security policy enforcement. However, SDN's centralized nature also introduces vulnerabilities, particularly to cyberattacks targeting the controller and communication channels. This study presents a resilience assessment methodology for SDN under cyberattack conditions, leveraging Markov process theory to model system states and transitions. Three SDN architectures were evaluated under various attack scenarios, revealing that traditional configurations lack sufficient resilience against synchronous attacks and controller breaches. To address these vulnerabilities, we propose an enhanced SDN protection framework integrating controller redundancy, automatic reconfiguration mechanisms, and anomaly detection using Long Short-Term Memory (LSTM) networks. The methodology was validated through simulations in the EVE-NG environment, demonstrating improved SDN stability under cyber threats. These findings provide a foundation for designing more resilient SDN infrastructures, ensuring network continuity and security against evolving cyber threats.

By separating the data layer from the control layer in the software defined network and the possibility of centralized and programmable management, many limitations and common problems in traditional networks can be solved or improved. One of the existing problems in these networks is the issue of congestion and its control. In software defined networks, the use of information under the supervision of domain controllers and the collection of network statistics can be useful in controlling or preventing congestion. When an SDN switch node is subjected to many requests, the network becomes congested, and to solve this problem, the controller can use network virtualization and switch migration, taking into account the free resources available in the switches and links.  In this paper, a software-based network approach for congestion control and optimal resource management called VNR_CCP is presented. In this approach, an attempt has been made to control congestion by calculating the nodes and links profit to search for congestion and request the virtual network to reduce the existing load and manage resources. The result of the simulation using the NS2 simulator shows that the proposed approach has better performance compared to the similar method. It was concluded that the throughput has increased by 4.3%, the delay has decreased by 5.3%, and the average cost has decreased by 26% compared to the similar method..

Objective: To compare the efficacy of using mild ovarian stimulation protocol and conventional stimulation protocol in IVF outcome.Materials and Methods: We randomized 200 women with regularly menstruation who were candidate for IVF. They had undergone stimulation with clomiphene citrate, gonadotropin and GnRH antagonist or gonadotropin and GnRH agonist.Results: There were no significant difference in mean age, cause of infertility, basal FSH, BMI, endometrial thickness on the HCG administration and clinical pregnancy rate in two groups. The number of recovered oocytes, embryos obtained, embryos transferred,, peak estradiol on the HCG administration and OHSS were significantly higher in agonist group. Significantly more patients in agonist group had embryo cryopreserved.Conclusion: The CC/ gonadotropin/ GnRH antagonist is an acceptable alternative protocol for IVF in patients with regularly menstruation.

Background: Recently different studies suggested that discontinuation of gonadotrophin releasing hormone analogue (GnRHa) at beginning of ovarian stimulation (improvement of ovarian response to gonadotrophins) may have some benefit to poor responder patients in invitro fertilization (IVF) cycles.Objective:The efficacy of GnRHa stop protocol in poor responder patients in IVF cycles was assessed.Materials and Methods: This study was a prospective, randomized controlled trial that 40 poor responder patients (less than three mature follicles in a previous cycle) with normal basal follicle stimulating hormone (FSH) were randomly allocated into two protocols: 1) Non-stop protocol: long GnRHa suppression, and start gonadotrophins from day 3 of mense. 2) Stop-protocol: GnRHa is stopped with the onset of menses, and gonadotrophin doses remained similar to group 1.Results: A significantly higher number of follicles, oocytes, embryos and fertilization rate also shorter stimulation days and lower human menopausal gonadotropins (HMG) ampoules were recorded in the stop protocol compared to the control group. Both protocols resulted in a similar cancellation rate, pregnancy rate, estradiol level and LH level.Conclusion: Early follicular cessation of GnRHa permitted the retrieval of a significantly higher number of follicles, oocytes and embryos, and can reduce the number of HMG and stimulation days.