OpenFlow and Cisco OPEN's feedback loop

The northbound SDN interface may limit OpenFlow's role and thwart commoditization

During its SDN conference call this week with Morgan Stanley and other participants, Cisco officials talked often about how a "feedback loop" is vital in its vision of a programmable network. This feedback loop would provide analytical data on users, sessions and applications gathered from the network to define policies and orchestration routines to be programmed back into the network.

The feedback loop is integral to Cisco's SDN architecture - the Open Programmable Environment for Networking, or Cisco OPEN. With a southbound interface, policy, orchestration, operational support and billing support applications tell the network what to do; but a northbound interface takes intelligence from the network to share with those applications so the applications themselves can make intelligent programming decisions based on that network intelligence.

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The northbound interface might be the key to Cisco's SDN strategy, as Brad Casemore points out here. OpenFlow is more of a southbound interface that directs switches from a centralized controller. The Open Networking Foundation, of which Cisco is an active participant, is looking to ruggedize and standardize OpenFlow as much as possible for this task.

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But Cisco doesn't want its switches to be dumb servants to a one-way southbound SDN interface, be it OpenFlow or any other. Cisco prides itself on building intelligent networks. It invests billions in custom ASICs and software to build up and maintain intelligence in its hardware, and it makes many more billions back from its 70% share in switching, 80% share in enterprise routing and nearly 60% share in service provider routing. This is the value that Cisco refers to when it says, as it did this week in the Morgan Stanley call, that SDNs should harness the entire value of the underlying network.

This is why Cisco is proposing Cisco OPEN, which is intended to open up the network with APIs at layers other than just the data and control plane, which is where the popular OpenFlow protocol is targeted. Cisco may cede the southbound data/control plane interface to OpenFlow; but all other interfaces at all other layers in Cisco OPEN are likely to be Cisco, including the northbound one that collects network analytics and delivers it to the control applications and creates the feedback loop -- or to Cisco, the value of SDN.

Cisco said during the Morgan Stanley call that SDNs and OpenFlow will not commoditize its hardware. Hardware will only be commoditized when value is not created. OpenFlow in and of itself does not create value for Cisco, even though IDC says OpenFlow hardware, software and services will be a $2 billion market by 2016. But OpenFlow within the context of Cisco OPEN does create value for Cisco.

Rather than commanding - controlling -- the SDN army, OpenFlow becomes just another foot soldier with a specific role in the lower ranks of the Cisco OPEN feedback loop.

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