الشبكات المعرفة برمجيا SDN هي عبارة عن بنية شبكية جديدة توفر التحكم المركزي بكامل الشبكة. يعمل هذا المتحكم كنظام تشغيل يقوم بإرسال التعليمات وتطبيق التغييرات من خلال الواجهات التخاطبية بينه وبين الأجهزة المسؤولة عنها ويدعى بالمتحكم.
Decoupling the decision-making process from the data forwarding process is the heart of
software-defined networks technology. One of the most important components of this
technology is the controller, which is the smartest component in the network.
Many of the
controllers have been developed since the technology originated, and many researches
have been done to compare the performance of these controllers for productivity, delay and
protection.
And due to the importance of selecting the appropriate controller according to different
parameters and network states, we studied the performance of four controllers: Floodlight,
Beacon, Nox, RYU in terms of productivity, RTT, time of establishing connection with an
OpenFlow switch and the time for adding an input to the switch flow table. The results
showed that the Beacon control was superior in performance when the number of switches
in the network was equal to the number of processor cores used by the controller. For RTT
and the time needed to add an input to the flow table, the NOX controller achieved less
time. Finally, the Floodlight controller was the best in terms of establishing connection
with the switch because it needed less time.
Current traditional IP networks start to be complex as the demands of the users are ever-growing. Software Defined Network (SDN) is a new paradigm to ease the management of the network and make the network programmable by decoupling the control plane
and forwarding plane (such as switch and router). A centralized controller is used to manage the control plane, and it interacts with the forwarding plane using a standardized OpenFlow protocol. However, many controllers are used recently such as POX, Ryu, ONOS, and OpenDaylight. The important question is which is the best controller to use in our network and fits our network’s goals? To answer this question, a decision-making method is proposed in this paper. First, four SDN controllers are selected, and five criteria are analyzed to collect these controllers’ properties. Then a Multi-Criteria Decision Making method named TOPSIS is used to rank the controllers and choose the best one. By applying this method, a comparative study is done to evaluate the four controllers in an environment of LAN topology, and “Ryu” controller is selected as the best one based on our criteria.
Device to device Communications (D2D Communications) is a new promising
technology, that is used to increase data exchanged volume, to expand the
coverage area of base stations, core network data offloading, and to move to
new frequency bands that have not been used in mobile networks before.
In this paper we introduce a specification model for the host migration
process in Software Defined Network, and for verifying the reachability
property for packets that do not change after the migration, and achieve
the required modifications to
meet the same properties.
The model is designed by TLA+ language and verified by TLC which is
correlated with it. The model is implemented by few states to meet the
required property.
In this paper the network specification by logic algebra is presented then
the packets are classified into reachable packets and dropped packets
according to the current state of the network and flow tables of switches.
The model specification is
written by TLA+ language which is built on
First Order Logic (FOL), and the specification is checked by TLC.
This model will help the programmers to detect the network in proactive
verification and prove that this configuration meets the global policy of
the network.
We present in this thesis a new structure that incorporates SDN with Vanets, and we make a meticulous study of routing mechanisms and their effects on security aspects. We also present a new security system that depends on public key infrastructure,
and finally we demonstrate how to benefit from SDN in facing several security attacks and preaches, which are common in traditional Vanets, through number of security algorithms which allow deploying intrusion detection systems as a step towards self-healing and self-configuration system.
