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Is OpenFlow Useful?

The Does Centralized Control Plane Make Sense post triggered several comments along the lines of “do you think there’s no need for OpenFlow?

TL;DR version: OpenFlow is just a low-level tool. Don’t blame it for how it’s being promoted.

OpenFlow is just a tool that allows you to install PBR-like forwarding entries into networking devices using a standard protocol that should work across multiple vendors (more about that in another blog post). From this perspective OpenFlow offers the same functionality as BGP FlowSpec or ForCES, and a major advantage: it’s already implemented in networking gear from numerous vendors.

Where could you use PBR-like functionality? I’m positive you already have a dozen ideas with various levels of craziness; here are a few more:

OpenFlow has another advantage over BGP FlowSpec – it has the packet-in and packet-out functionality that allows the controller to communicate with the devices outside of the OpenFlow network. You could use this functionality to implement new control-plane protocols or (for example) interesting layered authentication scheme that is not available in off-the-shelf switches.

Summary: OpenFlow is a great low-level tool that can help you implement numerous interesting ideas, but I wouldn’t spend my time reinventing the switching fabric wheel (or other things we already do well).

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2 comments:

  1. Open flow do it in much simplier way and improve managebility a lot. It made obsolate all cisco expensive protocols and hw.

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    Replies
    1. And this opinion happens to be based on what empirical data?

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