Without Standards Conformance, OpenFlow Fails to Deliver Interoperability

  • Mike Fratto
    Mike Fratto

    Standards without conformance are useless. Conformance testing resolves varying interpretations which enables interoperability.

  • OpenFlow is starting to fragment along product and vendor partner lines, which isn’t good for either vendors or customers.

When it comes to standards, most if not all IT professionals agree that standards are important. The obvious reason is that standards allow enterprises to integrate the software and hardware they want to use rather than being confined to a subset of products from one vendor or a vendor’s partner program. That’s the high road. The reality is that IT just wants equipment that works whether or not they are standards based, and that’s because having a technical standard isn’t going to enable interoperation and integration.

Think of standards documents as making a lot of suggestions and a few demands. In between the suggestions and demands there is plenty of room of interpretation that ultimately results in “standard compliant but not interoperable” implementations.  SIP is a recent example of such a standard that is widely implemented yet not interoperable without dedicated engineering resources from all vendors involved ensuring that everyone is interpreting the standards in the same way and then resolving any gaps.

OpenFlow is in a similar place and many in IT wonder if this protocol is really ever going to be interoperable. There have been a few plugfests where vendors gathered and tested equipment but this approach doesn’t lead to interoperation—at least not directly.

Enter Big Switch and its open source OpenFlow firmware that can run on merchant silicon called Switch Light. One of the stated goals of Switch Light is to ensure that any switch running the firmware can interoperate with any other switch running the same firmware. It’s the same code base, so interoperational bugs should be minimized. Extreme has already announced support of Switch Light, the first commercial vendor to do so.

It’s good of Big Switch to make Switch Light open source. If it starts to see adoption by vendors using merchant silicon, then it’s possible that collectively Switch Light and the products that use it could become a reference architecture against which all other OpenFlow products are tested. There’s a whole lot of “ifs” to be satisfied before that happens and for Switch Light to really take off; it will need the blessing of a network vendor with a much bigger market presence like Cisco, HP, or IBM. Of course, those vendors have their own OpenFlow plans in the works. If the network vendors and Switch Light continue on their current trajectory, Switch Light will end up being yet one more OpenFlow implementation that may or may not integrate with others.

The Open Networking Foundation (ONF) has a testing and interoperability group similar to the Wi-Fi Alliance for 802.11 wireless or the Metro Ethernet Forum for carrier Ethernet, but there hasn’t been much movement since March 2012. The ONF has the mind share and credentials to drive a conformance program, but they need to make it a priority. Otherwise, OpenFlow will fragment like SIP and slow the chances for interoperation to a crawl.

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