“The goal of the Openflow initiative is to create an overlay mechanism that directs where packets go. This sits on top of the network of routers and switches that are used to actually move the packets” – Article on Openflow in GigaOM Blog.
“Networking can be pulled into the application stack, instead of apps continuing to simply ride atop the infrastructure” – Article on Openflow in Cisco’s blog.
“Because Openflow enabled solution allows users to manage the network more pro-actively and more centralized way, the network can be more dynamic and more responsive to business needs” – Article on Openflow in Hp’s blog.
What are the current challenges in a network? Scalability? Disparate and multi-vendor overlay networks? Long time required for re-configuring the global network parameters? Inflexibility? Distributed control and management planes?
Openflow is a new and upcoming networking protocol that might just take networking in a new direction altogether by allowing an external controller to control forwarding decisions of a group of switches / network devices. So, the intelligence that gets built into each network switch today might get centralized in the future!
Openflow is an open-standards based protocol and it was initially developed by Stanford University. Openflow decouples firmware and network services (control and management plane) from the hardware (data plane). Openflow separates the packet switching mechanism and control functions.
The packet switching is performed as usual by network switches. But the control functions are done by a specialized network device called Openflow Controller. In fact, the controller centralizes the control functions for a group of switches. So, when a packet arrives at a switch the switch consults the controller on where to send the packet (next hop).
Openflow is not limited to network switches, but it can be implemented in routers and access points as well. Besides, many network switches today allow to implement openflow on a few ports, while the remaining ports operate normally using the existing (in-built) control plane.
This capability has proved useful in academic environments where researchers might want a live / high-volume prototype network to develop and test new protocols / applications using Openflow. There is at least one vendor focused on developing Openflow Controllers.
So, what might be the applications of Openflow?
- Developing and testing new network protocols that can substitute existing protocols like OSPF.
- Faster and advanced forwarding, tailor-made for big networks like private or public clouds.
- Programmability and applications to extend the network switching functionality.
- Centralize Switching Intelligence and allow for faster re-configuration of whole networks.
- Re-route data flow dynamically during network congestion.
- Detect and manage DoS attacks better.
- Allow organizations / researchers to build their own custom network topologies, etc.
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