Following recent announcements from Juniper and HP, Citrix came out with its software defined networking strategy today that looks to automate applications that run on virtualised networks.

Citrix announced that the latest version of its NetScaler SDX application deliver controller (ADC) will be available next year and optimised for software defined networks. Citrix also announced a series of partnership with companies whose applications will run in this environment, including: Aruba Networks, BlueCat Networks, CSE SecureMatrix, Palo Alto Networks, RSA, Splunk, Trend Micro, Venafi and WebSense.

Sunil Potti, vice president/general manager of cloud networking for Citrix says the SDN battle-lines have been drawn after VMware bought Nicira and a bevy of other providers began releasing SDN controllers. "Now, the next chapter has opened," he says, and that will be focused on the applications that run on the virtualised network.

Last year Citrix announced NetScaler SDX, which gives multi-tenant capabilities to its ADC, allowing multiple NetScalers to run in a single box. Today's announcement is about optimising applications to run on emerging virtualized networks, Potti says. "The network is built to serve the applications," he says. "(The industry is) building the next generation of the network, but we're missing on the opportunity to link in the learning of the last 20 years. Why not embed application intelligence from the top down?"

Andre Kindness, a Forrester networking analyst, says the move feels more like enabling cloud-like capabilities than a true SDN one. "This allows you to share a piece of hardware and get more capabilities out of it," he says, noting additional multi-tenant capabilities to the ADC.

But he says it's an important discussion that's been missing from the SDN debate so far. Much of the SDN discussion has been at the lower level L2 and L3, but Citrix is looking to optimize layers 4-7 for the underlying virtualized L3.

The strategy is markedly different, but somewhat complementary from what other SDN players have been doing so far, says consultant Jim Metzler of Ashton, Metzler & Associates. "The HP, Juniper and other announcements involve a controller that will provide control functionality to L2 and L3 devices; e.g., switches and routers," he wrote in an e-mail. "What Citrix announced is that they will leverage their technology to provide a control plane to L4 - L7 devices. The Citrix products add value on a stand-alone basis but also add value by sending info to an SDN controller from a company like HP to pass control information down to the L2 & L3 devices."