附录A 外文原文OpenFlow: Enabling Innovation in Campus NetworksNick McKeownStanford UniversityGuru ParulkarStanford UniversityTom AndersonUniversity of WashingtonLarry PetersonPrinceton UniversityHari BalakrishnanMITJennifer RexfordPrinceton UniversityScott ShenkerUniversity of California,BerkeleyJonathan TurnerWashington University inSt. LouisThis article is an editorial note submitted to CCR. It has NOT been peer reviewed.Authors take full responsibility for this articles technical content.Comments can be posted through CCR Online.ABSTRACT This whitepaper proposes OpenFlow: a way for researchers to run experimental protocols in the networks they use every day. OpenFlow is based on an Ethernet switch, with an internal ow-table, and a standardized interface to add and remove ow entries. Our goal is to encourage networking vendors to add OpenFlow to their switch products for deployment in college campus backbones and wiring closets. We believe that OpenFlow is a pragmatic compromise: on one hand, it allows researchers to run experiments on heterogeneous switches in a uniform way at line-rate and with high port-density; while on the other hand, vendors do not need to expose the internal workings of their switches. In addition to allowing researchers to evaluate their ideas in real-world traffic settings, OpenFlow could serve as a useful campus component in proposed large-scale testbeds like GENI. Two buildings at Stanford University will soon run OpenFlow networks, using commercial Ethernet switches and routers. We will work to encourage deployment at other schools; and we encourage you to consider deploying OpenFlow in your university network too. Categories and Subject Descriptors C.2 Internetworking: Routers General Terms Experimentation, Design Keywords Ethernet switch, virtualization, flow-based 1. THE NEED FOR PROGRAMMABLE NETWORKS Networks have become part of the critical infrastructure of our businesses, homes and schools. This success has been both a blessing and a curse for networking researchers; their work is more relevant, but their chance of making an impact is more remote. The reduction in real-world impact of any given network innovation is because the enormous installed base of equipment and protocols, and the reluctance to experiment with production traffic, which have created an exceedingly high barrier to entry for new ideas. Today, there is almost no practical way to experiment with new network protocols (e.g., new routing protocols, or alternatives to IP) in sufficiently realistic settings (e.g., at scale carrying real traffic) to gain the condence needed for their widespread deployment. The result is that most new ideas from the networking research community go untried and untested; hence the commonly held belief that the network infrastructure has “ossied”. Having recognized the problem, the networking community is hard at work developing programmable networks, such as GENI 1 a proposed nationwide research facility for experimenting with new network architectures and distributed systems. These programmable networks call for programmable switches and routers that (using virtualization) can process packets for multiple isolated experimental networks simultaneously. For example, in GENI it is envisaged that a researcher will be allocated a slice of resources across the whole network, consisting of a portion of network links, packet processing elements (e.g. routers) and end-hosts; researchers program their slices to behave as they wish. A slice could extend across the backbone, into access networks, into college campuses, industrial research labs, and include wiring closets, wireless networks, and sensor networks. Virtualized programmable networks could lower the barrier to entry for new ideas, increasing the rate of innovation in the network infrastructure. But the plans for nationwide facilities are ambitious (and costly), and it will take years for them to be deployed. This whitepaper focuses on a shorter-term question closer to home: As researchers, how can we run experiments in our campus networks? If we can gure out how, we can start soon and extend the technique to other campuses to benet the whole community. To meet this challenge, several questions need answering, including: In the early days, how will college network administrators get comfortable putting experimental equipment (switches, routers, access points, etc.) into their network? How will researchers control a portion of their local network in a way that does not disrupt others who depend on it? And exactly what functionality is needed in network switches to enable experiments? Our goal here is to propose a new switch feature that can help extend programmability into the wiring closet of college campuses.One approach -that we do not take -is to persuade commercial “name-brand” equipment vendors to provide an open, programmable, virtualiz