Power of Open Choice in Hypervisor Virtual Switching

Customers gain great value from server virtualization in the form of virtual machines (VM) and more recently Linux Containers /Dockers in data centers, clouds and branches.  By some estimates, more than 60 % of the workloads are virtualized although less than 16% of the physical servers (IDC) are virtualized (running a hypervisor).  From a networking perspective, the hypervisor virtual switch on these virtualized servers plays a critical component in all current and future data center, cloud, and branch designs and solutions

As we count down to the annual VMworld conference and reflect on the introduction of the Cisco Nexus 1000V in vSphere 4.0 six years ago, we can feel proud of what we have achieved. We have to congratulate VMware for their partnership and success in opening vSphere networking to third party vendors. It was beneficial for our joint customers, and for both companies. VMware and Cisco could be considered visionaries in this sense. Recognizing this success, the industry has followed.

Similarly we praise Microsoft as well, for having also provided an open environment for third-party virtual switches within Hyper-V, which has continued gaining market share recently.  Cisco and Microsoft (along with other industry players) are leading the industry with the latest collaboration on submitting the OpFlex control protocol to the IETF. Microsoft’s intention to enable OpFlex support in their native Hyper-V virtual switch enables standards-based interaction with the virtual switches.  Another win for customers and the industry.

In KVM and Xen environments, many organizations have looked at Open vSwitch (OVS) as an open source alternative. There is an interest in having richer networking than the standard Linux Bridge provides, or using OVS as a component for implementing SDN-based solutions like network virtualization. We think that there is an appetite for OVS on other hypervisors as well.  Cisco is also committed to contributing and improving these open source efforts.  We are active contributors in the Open Virtual Switch project and diligently working to open source our OpFlex control protocol implementation for OVS in the OpenDaylight consortium.

To recap on the thoughts from above, Table 1 provides a quick glance at the options for virtual networking from multiple vendors as of today:

Table 1:  Hypervisors and Choices in Virtual Switches


Native vSwitch

3-party or OpenSource  vSwitch


•Standard vSwitch
•Distributed Virtual Switch
•Cisco Application Virtual Switch
•IBM DVS 5000V
•HP Virtual Switch 5900V


Native Hyper-v Switching


Linux Bridge(some distributions include OVS natively)


OVS – open source project with multiple contributions from different vendors and individuals


As an IT Professional, whether you are running workloads on Red Hat KVM, Microsoft Hyper-V or VMware vSphere, it is difficult to imagine not having a choice of virtual networking. For many customers, this choice still means using the hypervisor’s native vSwitch.  For others, it is about having an open source alternative, like OVS. And in many other cases, having the option of selecting an Enterprise-grade virtual switch has been key to increasing deployments of virtualization, since it enables consistent policies and network operations between virtual machines and bare metal workloads.

As can be seen in the table above, Cisco Nexus 1000V continues to be the industry’s only multi-hypervisor virtual switching solution that delivers enterprise class functionality and features across vSphere, Hyper-V and KVM. Currently, over 10,000 customers have selected this option with Cisco Nexus 1000V in either vSphere, Hyper-V, or KVM (or a combination of them).

Cisco is fully committed to the Nexus 1000V for vSphere, Hyper-V and KVM and also the Application Virtual Switch (AVS) for Application Centric Infrastructure (ACI), in addition to our open source contributions to OVS.  Cisco has a large R&D investment in virtual switching, with a lot of talented engineers dedicated to this area, inclusive of those working on open-source contributions.

Nexus 1000V 3.0 release for vSphere is slated for August 2014 (general availability). This release addresses scale requirements of our increasing customer base, as well as an easy installation tool in the form of Cisco Virtual Switch Update Manager.   The Cisco AVS for vSphere will bring the ACI policy framework to virtual servers.  With ACI, customers will for the first time benefit from a true end-to-end virtual + physical infrastructure being managed holistically to provide visibility and optimal performance for heterogeneous hypervisors and workloads (virtual or physical).  These innovations and choices are enabled by the availability of open choices in virtual switching within hypervisors.

As we look forward to VMworld next month, we are excited to continue the collaborative work with platform vendors VMware, Microsoft, Red Hat, Canonical, and the open source community to maintain and continue development of openness and choice for our customers.  We are fully committed to this vision at Cisco.

Acknowledgement:  Juan Lage (@juanlage) contributed to this blog.

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  1. I appreciated the table offered in this blog that provides a complete summary of existing virtual switching offering.
    Both N1k and OVS seem in the best position to be the two leading contenders for hypervisor agnostic customers.
    But you say it well: in the end, customers are the ones who pay and decide and they should be given choice from tech vendors.

  2. With VMware’s constant innovation with NSX what is Cisco doing to ensure the 1000v maintains a place in the data center? It seems as though the 1000v is being cut from VMware vCloud deployments and certain things can only be achieved by using NSX vs. 1000v. My concern is the “Cisco” network presence being removed when data centers have a large VMware virtual environment or cloud deployments…

    • Hi Michael, Thanks for your comment. Nexus 1000V has addressed specific needs of many of our customers requiring segmentation (VSG) and Cisco Nexus OS features across multiple hypervisors and orchestration platforms. Also, we recently introduced Application Centric Infrastructure and as part of that we introduced Application Virtual Switch. AVS is managed directly from the APIC (ACI controller) and hence ACI offers full end-to-end visibility, local switching/forwarding and policy enforcement at the hypervisor level. In our view, you need to consider Cisco’s physical + virtual with heterogenous hypervisor support compared to primarily VMware centric NSX solution. You should visit http://www.cisco.com/go/aci for more information about offering.

      Thanks again for taking time to read our article and hoping you agree with the primary premise that we need open choice in hypervisor vSwitching offerings and hence choice in DC/cloud solutions.

  3. You said “By some estimates, more than 60% of the workloads are virtualized although less than 16% of the physical servers (IDC) are virtualized (running a hypervisor).”

    That being said, according to Gartner, less than a third of the Linux servers in data center have been virtualized. So, there’s apparently lots of untapped optimization.

    Granted, the rising license fee costs of traditional virtualization solutions, such as vSphere, are likely to be a key inhibitor for some CIOs and IT managers.

    In contrast, the alternatives you mentioned — such as Red Hat Virtualization — are a good choice for those who want to reduce their OPEX with a lower-cost open source KVM-based subscription. In fact, there are significant additional savings when combining enterprise Linux + Virtualization http://red.ht/KBgLO5

    Clearly, as you say, there’s also a huge advantage for those who previously deployed only VMware solutions to migrate to a multi-Hypervisor configuration. Reduced ongoing data center operating costs are just one of the very real benefits enabled by a multi-vendor coexistence strategy.

    • Hi David, Thanks for taking time to read and respond to this blog. I am in complete agreement that ton of customers are deploying at Hyper-V and KVM/OpenStack solutions and there is huge cost savings going down that path.

      Thanks again