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Wednesday, February 27, 2013

What is Openflow

The OpenFlow standard is no longer anything new but rather a new low level protocol that network vendors are implementing in upcoming hardware. For these who would like to find out more about how it works and what it does the 'Origins and Evolution of OpenFlow/SDN - Martin Casado' video will give you a quick introduction. Below I put as well some of my notes I found interesting.

What is Openflow
  • Openflow is an interface to the switch.
  • It relays on the existing hardware you have; the hardware will still perform the same. functions it was originally designed for but we are going to have better manageability interface.
  • It allows us to decouple data plane from control plane.
  • It allows to create a more agile network environment in comparison to conventional network architectures.
Why we need Openflow

We have been taught that network is reliable, robust and can easily handle any type of changes. But in reality the bigger the network the more static it becomes. It is harder and harder to implement any changes. And to get it done it may requires a lot of careful planing and detailed implementation steps. As an example for a single change you may need to:
  • Reconfigure switches and change security parameters.
  • Adjust VLAN id.
  • Reconfigure your (global) routing policies.
  • change ACL on FW.
Often because of the operational complexities your network have to be simplified and follow certain constrain how the whole topology can look like. When it comes to changes we can never exclude the human error factor as well of course.

What problem does Openflow and SDN try to solve
  • Unified and vendor independent API to mange data plan in network hardware.
  • Provide API to manage state on the network device.
  • Provide a pragmatic way how to manage all of the datapath state in the network.
  • Decouple the software control distribution model from network hardware and topology.
  • Logically centralize control plane in the loosely coupled heterogeneous environments.
  • What openflow and sdn does it allows you to decouple the distribution model of your control logic from the physical topology.
What are the values and benefits of Openflow and SDN
  • Allow development of new network models and new types of function and services.
  • Innovate in the network as well network infrastructure areas.
  • Horizontal integrity.
  • The decoupling of the control and data layers will help to evolve them independently and lead to creation of better products.
  • With SDN you can do new things that are not possible within standard network - for example complete network tearing down and provisioning on demand
  • SDN is the way how you can manage the complexity within your distributed network
  • Allow to innovate on faster speed in networking

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