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.
This study was conducted on domestic pigeons and back yard
chickens populations in many regions of Syrian Arab Republic
using techniques of isolation on chicken embryo and cell culture.
The birds were suspected to be infected by pox virus through
clinical symptoms by the presence of lesions in warts and scars
on Different areas of the face as the comb, wattle, the corner of
the mouth and eyelids and other areas of body and we notice
presence of Diphtheric lesions on the mucous membrane of the
oral cavity in many cases.
