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Software-defined networking (SDN) is an approach to computer networking that allows network administrators to manage network services through abstraction of higher-level functionality. This is done by decoupling the system that makes decisions about where traffic is sent (the control plane) from the underlying systems that forward traffic to the selected destination (the data plane). The inventors and vendors of these systems claim that this simplifies networking. SDN requires some method for the control plane to communicate with the data plane. One such mechanism, OpenFlow, is often misunderstood to be equivalent to SDN, but other mechanisms could also fit into the concept. ==History== The origins of software-defined networking (SDN) began shortly after Sun Microsystems released Java in 1995.〔(【引用サイトリンク】 title=The History of Java Technology )〕〔(Sun Pegs Telecom with JTONE )〕〔(Sun facilitates Java use for public network operators )〕 One of the first and most notable SDN projects was AT&T's GeoPlex.〔(【引用サイトリンク】title=CERIAS : GeoPlex: Universal Service Platform for IP Network-based Services - 10/17/1997 )〕 AT&T Labs Geoplex project members Michah Lerner, George Vanecek, Nino Vidovic, and Dado Vrsalovic leveraged the network APIs and dynamic aspects of the Java language as a means to implement middleware networks. "GeoPlex is not an operating system, nor does it attempt to compete with one. It is networking middleware that uses one or more operating systems running on computers connected to the Internet. GeoPlex is a service platform that manages networks and on-line services. GeoPlex maps all of the IP network activities into one or more services."〔(【引用サイトリンク】title=Middleware Networks )〕 As noted, GeoPlex did not concern itself with operating systems running on networking hardware switches, and routers. AT&T wanted a "soft switch" that could reconfigure physical switches in the network and load them with new services from an OSS. However, when provisioning services GeoPlex could not reach deeply into the physical devices to perform reconfiguration. The operating systems running on networked devices in the physical network therefore became a barrier to early SDN-like service delivery. In 1998, Mark Medovich, a senior scientist of Sun Microsystems and Javasoft, left Sun to launch a Silicon Valley soft switch startup WebSprocket. Medovich designed a new network operating system, and an object oriented structured runtime model that could be modified by a networked compiler and class loader in real time. With this approach, applications could be written with Java threads that inherited WebSprocket kernel, network, and device classes and later modified by the networked compiler/class-loader. WebSprocket's platform was designed such that devices had the ability to instantiate network stack(s), interfaces, and protocols as multiple threads. In July 2000, WebSprocket released VMFoundry, the Java to bare metal structured runtime compiler, and VMServer, a networked device compiler/classloader application server.〔(【引用サイトリンク】title=Websprocket Announces VMServer - World's First Proxy Java Virtual Machine; Enables 1,000's of Connected Clients To Use Single Java Virtual Machine. )〕 Custom networked devices were preloaded with images created by VMFoundry then deployed on the network and connected to VMServer via UDP or TCP services plane, which could proactively or reactively load or extend network protocol methods and classes on the target system. WebSprocket's version of SDN, therefore was not confined to a set of limited actions managed by an SDN controller. Rather, WebSprocket's "control plane" contained code that could change, override, extend, or enhance Network protocols on operating networked systems.〔(【引用サイトリンク】title=Installation Guide )〕 Bill Yount (Stanford University Network) visited WebSprocket's Sunnyvale lab to see a demonstration and expressed great enthusiasm about the entire concept, especially the VMServer (SDN Controller) and prophetically stated SDN (WebSprocket) as "10 years ahead of its time". In Summer of 2000, Ericsson's advanced network research engineers saw an immediate need and visited WebSprocket to design and architect features of a next generation soft switch thus taking first steps to build the world's first commercial soft switch. Sometime during 2000, the Gartner Group recognized the emergence of programmable networks as the next big thing for the Internet and introduced the "Supranet", the fusion of the physical and the digital (virtual) worlds as "internet of things," and by October 2000 the Gartner Group selected WebSprocket as one of the top emerging technologies in the world.〔(【引用サイトリンク】title=Top Emerging Technologies Announced During Gartner Symposium/ITxpo 2000; New Emerging Technologies Research Highlights Trends in Wearable Computing, Profiling and Privacy. )〕 In early 2001, Ericsson and WebSprocket entered into a license contract to create the first commercial soft switch. Ericsson's entire (SCS) call control software stack was ported by Joe Kulig (WebSprocket) in a matter of days, a feat that astounded Ericsson. An international consortium was formed to develop standards for the "Supranet". In March 2001, Kurt Dewitt, Supranet Consortium Chairman and Business Development Director for Ericsson's Data Broadband and Optical Networks Division, announced the selection of WebSprocket as the enabling technology of the Supranet Transaction Server (STS), a comprehensive framework to deliver any networked service.〔(【引用サイトリンク】title=Websprocket Selected By Supranet Consortium to Enable the Internet With Smart Packet Technology; Platform Unifies Supranet Management Through Java and Oracle. )〕 In April and May 2001, Ohio State University and OARnet, collaboratively ran the first SDN test and developed the first practical SDN use case for Internet2. After successful completion of tests, OARnet issued the following statement on May 8, 2001: The telecom market deflated in 2001 and Ericsson's soft switch development program came to an end, thus stalling the only known commercial SDN soft switch R&D effort at that time. Software-defined networking (SDN) was continued with work done in 2003 by Bob Burke and Zac Carman developing the Content Delivery Control Network patent application that eventually was issued as two US patents: 8,122,128 〔(【引用サイトリンク】title=United States Patent: 8122128 )〕 and 8,799,468.〔(【引用サイトリンク】title=United States Patent: 8799468 )〕 In this seminal inception, SDN, named service preference architecture (SPA) in their patent, was described as a collection of network embedded computing techniques used to control the operation of Network Elements, namely content servers, routers, switches and gateways, with the objective being to safeguard content from theft (P2P) or unwanted interception and to efficiently deliver content for paid services. CableLabs later specified Digital Cable and CableCARD using what we now know as SDN, which debuted in 2007. SDN was again moved ahead in work done at UC Berkeley and Stanford University around 2008. The Open Networking Foundation was founded in 2011 to promote SDN and OpenFlow. At the 2014 Interop and Tech Field Day, software-defined networking was demonstrated by Avaya using Shortest path bridging and OpenStack as an automated campus, extending automation from the data center to the end device, removing manual provisioning from service delivery.〔(【引用サイトリンク】date=26 March 2014 )〕 The SDN has the potential of revenues growing from less than $15B in 2015 to nearly $105B by 2020. This growth is driven primarily by the network (L2/3) and network functions (L4/7) categories. The L2/3 contribution is expected to exceed $10B in 2015 and grow to more than $105B by 2020, while the network functions layer will grow from under $5B in 2015 to $32B by 2020. The SDxN market is projected to have a CAGR of 44% over the 5 years from 2015 to 2020, eight times the growth rate of the broader TAM. The portion of network purchases influenced by virtualization is anticipated to increase from 16% in 2015 to almost 80% by 2020. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Software-defined networking」の詳細全文を読む スポンサード リンク
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