ONOS controller architecture follows a true distributed computing model; the centralized controller operating system is distributed across several controller nodes. The difference might seem subtle, but is important. With ONOS, a single, distributed ONOS instance maintains a unified, global view of the network state.
ONOS also differentiates itself from ODL in that it is explicitly targeting service providers. While that doesn’t exclude enterprise users, many of whom have network architectures that look similar to service providers, ONOS has the global scale and ultra-high endpoint connection count of service providers in mind. ONOS also points out that it is involving end-users with vendors right at the start. This is a not-so-subtle jab at ODL, which has been criticized by some for being too vendor-driven.
While enterprise shops are unlikely to adopt ONOS, at least the way it looks today, the distributed controller architecture could be interesting. Enterprises that feel ODL is an SDN scale bottleneck may want to test ONOS in their environment to see if the architecture meets their expectations.
ONOS’s second release is called Blackbird, and has been available since March 2015. The third ONOS release, Cardinal, became available June 2, 2015. ONOS intends to release on a faster schedule than ODL (roughly every quarter), although the releases may not have as much new in them when compared to the amount of “new” that might be found in ODL major releases.
ONOS is seeing real-world use, including recently announced deployments in segments of Internet2. Key organizations involved in ONOS include AT&T, NTT Communications, SK Telecom, Ciena, Cisco, Ericsson, Fujitsu, Huawei, Intel, NEC, the Open Networking Foundation (the maintainers of OpenFlow), Infoblox, and several others.
Another interesting connection is the ONOS tie to the OPNFV project, which is creating a framework for Network Functions Virtualization for service providers. ON.Lab announced on May 8 the approval of a project to tie the OPNFV framework to ONOS. This is a timely connection to make, as OPNFV is also in its early stages. It seems likely that ONOS will map well into OPNFV constructs, resulting in a platform that some service providers will look to both for scale and function.
What’s it all mean?
For network consumers, the consolidation of SDN controllers offers at least two key benefits.
Developers can begin writing SDN applications with confidence, knowing what controllers they can count on being around for the long haul. An application that runs on the open source distribution of ODL should also run on ODL-based controllers released by network vendors. That means writing ODL applications is a market worth entering.
That’s not to say there isn’t a future in writing applications for proprietary vendor controllers, such as Cisco’s APIC or HP’s VAN, but those vendor-specific controllers may represent smaller markets that will be harder for application developers to capitalize on. With ODL especially seeing decent market penetration even at this early stage, network consumers should begin to see more applications come available over time.
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