How will SDN be deployed?
While the initial discussion of SDN focused on implementation in the data center, the scope has now widened. In order to understand where SDN will likely be implemented, survey respondents were asked, “If your organization is likely to implement SDN sometime over the next two years, where are you likely to implement it?” Their responses (Table 4) indicate that the primary focus is likely to be in the data center, however there is considerable interest in the WAN as well as in branch and campus networks.
Respondents were also asked to indicate how pervasively deployed SDN would be in their campus, WAN and data center networks three years from now. Their responses (Table 5) show marked inroads in the data center, but also significant deployment both in the WAN and in campus networks. Given the current status of SDN deployment (Table 1), these penetration rates seem overly optimistic.
How will SDN be implemented?
One of the key architectural differences between vendor SDN products is how they are implemented. The overlay model proposed by companies such as VMware and Nuage Networks, focuses on the hypervisor and tunneling and encapsulation. The fabric-based underlay-based model focuses on a range of virtual and physical network elements and relies on the SDN controller manipulating flow tables in the network elements. This is the model used by companies such as Cisco, NEC and HP.
Survey respondents were asked what relative value the overlay- and the underlay-based models will provide over the next two years. Their responses (Table 6) indicate, by a small margin, IT shops perceive the fabric-based SDN model will provide more value. However, many have yet to form an opinion.
Another one of the architectural distinctions between the varying ways vendor implement SDN is the role of dedicated hardware. Vendors such as VMware believe it’s possible to fully support network virtualization in the data center without using dedicated hardware. In contrast, vendors such as Cisco believe dedicated hardware is needed in at least some instances. The survey respondents were asked if they believed that, with the current technologies and products, it’s possible to broadly support network virtualization in the data center without using any dedicated hardware? Those that believed it was not possible outnumbered those that believe it is by almost a 2:1 ratio.
At one time many equated SDN and OpenFlow. To understand how IT organizations currently view that relationship, survey respondents were asked how likely it was that OpenFlow would play a role in their SDN implementation (Table 7). Most seem to have a favorable view of OpenFlow, but almost a third are still on the fence. (See related article.)
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