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How Cornell University is using OpenDaylight


When Cornell University designed the network for their new Computer and Information Sciences (CIS) facility, they knew from the onset that legacy technologies would not meet their goals and innovative vision for the future. The recently completed Bill and Melinda Gates hall was designed to serve as much more than a building, and is seen as an embodiment of the vision for the CIS program. The goals for the program are nothing less than “to be the national model for education and research that supports the information economy”. [i]

With aggressive goals like this, Cornell knew the new facility needed to be built with the latest and most innovative technologies. CIS dean Haym Hirsh said, “The pace of change in computing is so rapid that some cutting edge research and timely academic offerings can’t happen without rethinking the physical environment in which CIS activities take place,” observing further that Gates Hall “addresses a bottleneck that would have kept CIS from living up to its potential.” [i]


While Gates Hall is equipped with new innovations across all domains, the research network is of particular importance as it serves as a foundation that all CIS programs share and build upon. Modern research is also morphing at an incredibly rapid pace and now requires that researchers across the globe be able to dynamically connect their systems to collaborate in real-time.

With these transformative changes happening, connectivity has become critical to the modern research institute. At any given time any number of researchers need to be able to create their own virtual, global-scale networks – all across a common infrastructure.

With a critical need to build a network that can meet the unknown demands of the future, Cornell turned to SDN. “When we looked at the design for the network we needed to build, it had to be future-proof,” said CIS IT director Scott Yoest. Principal research scientist Robbert Van Renesse observed that “we did not know exactly what the applications of the future would be, so we decided that we wanted to go with an OpenFlow network so we would have lots of flexibility.”

To meet these needs Cornell implemented one of the largest pure-OpenFlow networks ever deployed into production at a University. Comprised of over 30 Dell S4810 and S4820 switches, the OpenFlow network delivers nearly 40 terabits-per-second of bandwidth to over 8000 students and faculty at CIS and has already expanded to provide service and support to several other schools and departments at Cornell.


Dave Juers, the engineer responsible for managing the OpenFlow network, is not a network engineer by trade – he started the conversation with a big disclaimer: “I am a biologist by training, I came into this through the back door.” So when he initially started learning about OpenDaylight, the learning curve was steep. Their first introduction to OpenDaylight (ODL) concepts was a high-level introduction. He said, “We had a training session in Silicon Valley where we used Mininet and Beacon to learn the basics of managing OpenFlow networks.”

They got a lot of support from their hardware partner Dell, who helped design and install the network. With the complex multi-tenancy and isolation needs of CIS, the ability for each physical switch to be virtualized and support multiple separate OpenFlow instances was crucial to their design. Since the switches are hybrid switches, some configuration was required to make the network 100% OpenFlow. The support was vital as the people managing the network are IT administrators, not programmers.


One of the key deciding factors for their choice of OpenDaylight was the fact that it is open source. The philosophical alignment of open source and community development provides the perfect environment for researchers looking to drive experimentation and innovation. Equally important was the breadth of available features and projects on the ODL platform which can greatly accelerate. After originally testing the controller on a Windows laptop, ODL is now deployed in production on Red Hat Enterprise Linux. Another key factor is ODL’s ability to program flows through a user interface. Juers said, “We didn’t want to have to connect through a command line interface to program the switches.”

The university has now been running OpenDaylight in production since mid 2014. The primary customers of the network are the Computer Science and Information Sciences departments, but the network has already expanded to now support the needs of several additional departments.

The network provides the infrastructure for multiple production workloads, including file servers for research projects, virtual machines for student work. One of the goals of Juers’ team was to reduce redundancy caused by multiple departments maintaining their own IT staff, and the OpenFlow network has been very useful in working towards that goal. One of the particularities of the university network is that many of the resources are on the publicly addressable internet, which creates numerous challenges especially in the area of security. ODL offered the ability to provide hardened isolation, dynamic instantiation of services and granular flow steering which are crucial for the network to deliver on rapidly increasing performance and security demands while still making these new capabilities manageable.


When we asked Juers what he was looking forward to in the future from OpenDaylight, his main request was access to more fine grained analytics and data from network devices. Better tools to get real-time diagnostics per-port, and to verify easily that data was flowing as intended through the underlying fabric, would make his life easier when diagnosing issues on the network.

The team is currently looking at migrating to the new Lithium release. They are already using Helium, and they hope to move the production network over soon to take advantage of stability and features in the newer release. One of the projects driving the upgrade is the deployment of Infrastructure-as-a-Service (IaaS) software on the network. IaaS is currently being deployed, and the OpenDaylight Lithium promises the ability to add key new features and benefits to the Gates Hall network.

What is his favorite thing about the OpenDaylight community? “They’re everywhere! I run into ODL people at conferences, I read their blogs. Vendors I speak with always have connections with and support the ODL community. Being part of the OpenDaylight community feels like being part of a movement.”