Software-De_ned Networking (SDN) proposes a new network architecture inwhich the control plane and forwarding plane are decoupled. SDN can improvenetwork e_ciency and ease of management through the centralization of the controland policy decisions. However, SDN deployments are currently limited todata-center and experimental environments. This thesis surveys the deploymentof SDN from the perspective of a telecommunication network operator. We discussthe strategies which enable the operator to migrate to a network in whichboth SDN and legacy devices interoperate. As a synthesis of existing technologiesand protocols, we formulate an automated process for the bootstrapping of newlydeployed forwarding devices. Furthermore, we review solutions for programmingthe forwarding devices and for performing topology discovery. The functionalcorrectness of the proposed bootstrapping process is evaluated in an emulatedenvironment.

Software Defined Networking (SDN) is a technology which provides a network architecture with three distinct layers that is, the application layer which is made up of SDN applications, the control layer which is made up of the controller and the data plane layer which is made up of switches. However, the exits different types of SDN architectures some of which are interconnected with the physical network. At the core of SDN, the control plane is physically and logically separated from the data plane. The controller is connected to the application layer through an interface known as the northbound interface and to the data plane through another interface known as the southbound interface. The centralized control plane uses APIs to communicate through the northbound and southbound interface with the application layer and the data plane layer respectively. By default, these APIs such as Restful and OpenFlow APIs do not implement security mechanisms like data encryption and authentication thus, this introduces new network security threats to the SDN architecture. This report presents a technique known as threat modeling in SDN. To achieve this technique, attack scenarios are created based on the OpenFlow SDN vulnerabilities. After which these vulnerabilities are defined as predicates or facts and rules, a framework known as multihost multistage vulnerability analysis (MulVAL) then takes these predicates and rules to produce a threat model known as attack graph. The attack graph is further used to performed quantitative risk analysis using a metric to depict the risks associated to the OpenFlow SDN model

本研究では李登輝政権以降の台湾における対外経済政策の変化メカニズムを検討した。構造レベルからの入力である米国の台湾政策と台湾企業は、台湾政府に対して対中投資規制の緩和と直航便の開設を求めてきた。これに対して台湾政府は、強固な抵抗・不安定な抵抗・構造への順応という3つの反応をしてきた。これを決定付けるのは、政権基盤の強弱・政権の重心・政権基盤の強化策というユニットレベルの3つの変数であることを明らかにした。 / This study examines the mechanism of changing foreign economic policy of Taiwan. The U.S. Taiwan policy and Taiwanese businesses, which were the inputs from the structure level, had demanded Taiwanese government to ease restrictions regarding investment to PRC and to introduce direct cross-strait link. Taiwanese government's reactions can be divided into three, which are 'Strict Resistance,' 'Partial Resistance,' and 'Accommodation to Structure.' This study shows that 'Strangeness of Administration's Political Power Base,' 'Administration's Direction,' and 'Way of Enforcing Administration's Political Power Base,' which are unit level variables, had determined which reaction the government would take. / 博士(政治学) / Doctor of Political Science / 同志社大学 / Doshisha University