OpenFlow and SDNS - Extreme Networks

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Extreme Networks White Paper: OpenFlow and SDNs Executive Overview OpenFlow is a new protocol implemented on an Ethernet switch that allows its forwarding plane to be managed by an external OpenFlow controller. An OpenFlow controller can manage a distributed set of network switches as a single virtual switch. As most OpenFlow controllers expose an API to applications, the controller and applications together behave as a unified Network OS, allowing a network operator to implement a Software Defined Network (SDN). OpenFlow Overview The OpenFlow protocol emerged from the Clean Slate research program at Stanford University. The objective was to enable researchers to experiment with new networking protocols and applications. Instead of porting each new protocol/application to switches, each brand with its own proprietary OS, the researchers need only port an OpenFlow protocol client, exposing the switch’s forwarding plane. The experimental control component could then be implemented on a standard PC running a Unix OS (such as Linux). This approach proved popular, and OpenFlow was adopted as a core component by university researchers participating in NSF GENI- and EU OPHELIA-funded research projects. OpenFlow protocol definition was opened to a group of interested researchers and networking vendors meeting periodically at Stanford, and via e-mail lists. OpenFlow version 1.0.0 was published in December 2009, and version 1.1 was published in February 2011. Multiple vendors, including Extreme Networks, have implemented OpenFlow 1.0 prototypes. Some of these prototypes were demonstrated at the Interop OpenFlow Interoperability Lab, in May 2011. OpenFlow exposes a switch’s forwarding plane as a set of Ethernet ports, flow tables, counters, queues, and capabilities. A flow table entry consists of a set of L2/L3/L4 match conditions, which may be variously wildcarded or masked. Associated with each flow table rule is a set of one or more actions, including Forwarding (to a physical or virtual port, to the controller, or flooded), Enqueueing, and Packet Modification. Added in OpenFlow 1.1 are support for multiple cascaded flow tables and MPLS label-related actions. By default, packets arriving at an OpenFlow-managed port which do not match a flow entry are encapsulated and sent to the controller, which as a result may send a flow installation command to the switch and return the packet back to the switch for forwarding. The wide generality of the OpenFlow flow match conditions allows a controller to manage forwarding at L2, L3, and/or L4 layers, either in isolation, or in combination. This enables a SDN with multiple virtualized network topologies. As a simple example, a controller can configure forwarding for UDP traffic on a special restricted topology, with guaranteed bandwidth allocated to dedicated queues used exclusively for UDP traffic. Industry Direction In March 2011, the Open Networking Foundation (ONF) was formed to advance the adoption of SDNs. ONF will manage future evolution and specification of the OpenFlow protocol, and may also define standard APIs to the OpenFlow controller, to allow for portable SDN applications. The board members are Deutsche Telekom, Verizon, Google, Facebook, Microsoft, NTT Communications, and Yahoo. ONF currently has 54 additional members, including Extreme Networks. See http://www.opennetworkingfoundation.org/ for more information. ONF published the OpenFlow 1.2 specification in December 2011. It also published the first version of the OpenFlow Configuration protocol, OF-Config 1.0, in January 2012. ONF working groups are currently working on new revisions of each specification, as well as defining the requirements for hybrid OpenFlow switches, and defining the long-term structure and evolution of the OpenFlow protocol. 2 © 2012 Extreme Networks, Inc. All rights reserved.
Extreme Networks White Paper: OpenFlow and SDNs Multiple vendors have implemented prototypes of OpenFlow 1.0, and a few have released generally available implementations. It is unclear whether OpenFlow 1.1 will be widely implemented; it is likely that most vendors will wait to refresh their implementations to OpenFlow 1.3 or later versions. The commercial landscape for SDNs includes not only switch vendors, but also controller vendors. The original controllers (Stanford, NOX, Beacon, SNAC) were developed by researchers and released as open source. NEC has announced a commercial controller, and two startup companies (Big Switch, Nicira), that spun out of the Stanford research team, are building commercial OpenFlow controllers, and have recently received venture capital funding. Initial SDN applications which have attracted interest in the campus, enterprise, and data center markets include multi-path support (to avoid the capacity loss and instability caused by STP and its failures), simplified administration of add/move changes (via managing the network as a single virtual switch), VM mobility and multi-tenancy (for hosting/cloud providers). SDN applications for the WAN including transport path provisioning and routing. Extreme Networks Opportunities Extreme Networks initiated development of OpenFlow support in ExtremeXOS® based in part on requests from various university customers involved in GENI- and OPHELIA-funded research projects. In the subsequent year demand for OpenFlow from university customers has expanded beyond the research lab into the production campus network. Extreme Networks is working with a major university customer to trial SDN applications within its campus network. Extreme Networks is also exploring opportunities with partners to deploy SDN applications in the enterprise campus and datacenter network environments. An SDN can serve as a platform to deploy a variety of intelligent network services in a scalable way, because the network switches are centrally managed by the OpenFlow controller. Of particular value are the network virtualization capabilities enabled. It becomes easier to deploy and dynamically manage security isolation between classes of users in university, enterprise campus or hospital networks, by isolating each class of user to their own virtual network topology. Unlike Ethernet VLANs, this isolation can also be enabled at the L3 and/or L4 layers. In a datacenter network, the network virtualization capabilities enabled by OpenFlow can simplify the provisioning of services for individual tenants, and can enable scalable VM migration across a large datacenter network or between physical datacenter sites. Extreme Networks Involvement Extreme Networks participated in the OpenFlow interoperability Lab at Interop 2011. Extreme Networks has also joined the ONF, and is participating in the future definition of the OpenFlow protocol. Current plans for Extreme Networks OpenFlow implementation include support as part of the ExtremeXOS network operating system, across a variety of switching products. Make Your Network Mobile Corporate and North America 3585 Monroe Street Santa Clara, CA 95051 United States Phone +1 408 579 2800 Europe, Middle East, Africa and South America Phone +31 30 800 5100 Asia Pacific Phone +65 6836 5437 Latin America Phone +52 55 5557 6465 www.extremenetworks.com © 2012 Extreme Networks, Inc. All rights reserved. Extreme Networks, the Extreme Networks logo, are either registered trademarks or trademarks of Extreme Networks, Inc. in the United States and/or other countries. All other names and marks are the property of their respective owners. Specifications are subject to change without notice. 1795_02 04/12
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OpenFlow and SDNS - Extreme Networks

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