OpenFlow opens new doors for network
With a new industry organization to promote it, routing protocol OpenFlow is about to give users unprecedented ease of control over the way their networks operate.
OpenFlow enables software-defined networking, which means that users can define flows and determine what paths those flows take through a network, regardless of the underlying hardware. Last month, this approach was embraced by a wide range of big-name industry players as they formed the Open Networking Foundation to push the protocol.
OpenFlow is an open source project borne of a six-year research collaboration between Stanford University and the University of California at Berkeley. OpenFlow can take control of how traffic flows through a network out of the hands of the infrastructure — the switches and routers — and put it in the hands of the network owner, individual users or individual applications. This capability could allow users to craft policies that find paths with available bandwidth, less latency or congestion, and fewer hops.
“OpenFlow is the first viable approach to software defined networking (SDN), and you can solve problems faster using SDN,” says Alex Reimers, a member of the technical staff at startup Big Switch Networks, a maker of OpenFlow controllers. “People want to control their own networks.”
What is OpenFlow?
OpenFlow is a protocol that enables SDN, which means that users can define flows and determine what paths those flows take through a network, regardless of the underlying hardware. OpenFlow can take control of how traffic flows through a network out of the hands of the infrastructure — the switches and routers — and put it in the hands of the network owner, individual users or individual applications. It separates the programming of routers and switches from underlying hardware. OpenFlow is an open source project borne of a six-year research collaboration between Stanford University and the University of California at Berkeley.
How does OpenFlow work?
The technology consists of three parts: flow tables installed on switches, a controller and a proprietary OpenFlow protocol for the controller to talk securely with switches. Flow tables are set up on switches. Controllers talk to the switches via the OpenFlow protocol and impose policies on flows. The controller could set up paths through the network optimized for specific characteristics, such as speed, fewest number of hops or reduced latency.
Why is OpenFlow needed?
Vendors offer varying degrees of user programmability on their routers and switches. This can lead to limited functionality for traffic engineering and management, or inconsistent traffic management between equipment from multiple vendors. OpenFlow is designed to provide consistency in traffic management and engineering by making this control function independent of the hardware it’s intended to control.
HP, for example, plans to stuff its 5406 switch chassis with server blades to configure the switch as an OpenFlow controller to manage and monitor quality-of-service delegations among OpenFlow switch clients. The company does not have a timeframe, however, for delivering this capability on the 5400 series switches, says Erik Papir, a technical marketing official in HP’s networking group.
Definition of SDN Architecture
SDN is a developing network architecture that aims to directly program the network computing. Through the open interfaces and abstraction of lower-level functionality, this approach allows the network administrators to programmatically initialize, control, change and manage network behavior dynamically. SDN is different from the traditional network architecture whose network devices are based on both control plane and data plane. Instead, SDN puts the control plane on the SDN controller to communicate with a physical or virtual switch data plane through the OpenFlow protocol.
Features of SDN
Here are some fundamental features of the SDN architecture:
- Instantly programmable: Network control is directly programmable for it is decoupled from forwarding functions.
- Agile: Administrators can dynamically adjust network-wide traffic flow to meet changing needs.
- Centralized management: Network intelligence is centralized in SDN controllers that maintain a global view of the network.
- Programmatically configured: Network managers can configure, manage, secure, and optimize network resources very quickly by dynamic, automated SDN programs.
- Open standards-based and vendor-neutral: SDN simplifies network design and operation since instructions are provided by SDN controllers instead of multiple, vendor-specific devices and protocols.
OpenFlow is a type of communication protocol that provides access to the forwarding plane of a network switch or router over the network. It is considered to be the first SDN standard, which enables network controllers to determine the path of network packets across a network of switches. In order to work in an OpenFlow environment, all the equipment should support the OpenFlow protocol to communicate to an SDN controller.
What Benefits Will OpenFlow-Based SDN Bring to Network?
- Point 1, SDN controller can get centralized control of OpenFlow-enabled devices from any vendors instead of managing the devices from different vendors separately.
- Point 2, OpenFlow-based SDN provides a flexible network automation and management architecture, and can develop a variety of automated network management tools to replace the current manual operation which greatly reduces the complexity.
- Point 3, SDN increases higher rates of business innovation and allows IT network operators to meet specific business needs and variable user needs in real time by explicitly programming or reprogramming the network.
- Point 4, SDN enables IT to define the configuration network and develop management policies at a higher level and distributes the information to the network infrastructure through OpenFlow, which has increased the network reliability and security.
- Point 5, OpenFlow’s flow control model allows IT to deploy network policies at a granular level which is a higher abstraction and automated deployment level including session-level, user-level, device-level and application-level.
- Point 6, through centralized network control and network application status information, SDN can provide better dynamic user experience.
OpenFlow skepticism
Indeed, there is still some caution in the industry regarding OpenFlow despite its growing momentum. And Avaya believes its switches can do the same things OpenFlow can do just by integrating programmable network processors. There’s also the sticky issue of security, especially when opening up the forwarding tables of multiple switches from multiple vendors.