VMware NSX networking: What you need to know before investing
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Are there any hardware or software requirements involved in deploying network virtualization platforms like NS...
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Virtualization has had a profound influence on system efficiency, allowing a software layer to host and manage multiple workloads sharing a pool of common computing resources. But the benefits of virtualization have only just started to penetrate the greater network, and vendors are introducing a new generation of tools intended to pool network resources, which can be allocated to specific workloads and even provisioned to higher-level tasks like cloud services.
When considering a network virtualization platform like VMware's NSX, it's important to ensure that the data center environment can accommodate the requirements. Start by considering support for the current hypervisor versions, since network virtualization typically interacts with virtual switch features of system hypervisors. NSX is compatible with other VMware products such as vSphere/ESXi, vCloud Director and vCloud Automation Center, but it is also compatible with XenServer and KVM along with OpenStack and CloudStack protocols.
The most noteworthy potential problem with NSX is the lack of support for physical networking devices. Products like NSX generally do not interact directly with network switches, routers and other devices, so the new virtualization layer is network-agnostic. However, translating physical device activity to virtual activity usually incurs a performance penalty unless VXLAN Termination End Point (VTEP) capabilities are available in the hardware devices. Switch operating software must also support the Open vSwitch Database (OVSDB) so that the network virtualization layer (NSX in this case) can interact with VTEP.
VTEP and OVSDB support is coming, but it may be years before they are both broadly available and interoperable among network device vendors. In the meantime, network performance may suffer under another layer of abstraction like NSX. It's a bit like server virtualization: It worked poorly until virtualization extensions like Intel-VT and AMD-V were widely available in server processors.
It's critical to verify these issues early in the evaluation process, otherwise it may be necessary to change or update problematic network devices. NSX provides a gateway function to nonvirtualized network systems and workloads, but be sure to evaluate the effect of mixing virtualized and nonvirtualized servers within network virtualization.
VMware's NSX uses a separate controller system to manage the interaction between hypervisor virtual switches. The controller then determines how to forward traffic across the network and make changes to the traffic flow as network conditions change (network virtualization bears similarities to software-defined networking in this respect). But, the presence of a controller will require at least one x86 server capable of running the required software. In many cases, multiple controllers are arranged into a cluster to provide resilience and workload balancing for critical network virtualization control tasks.
Be sure to also consider the importance of cloud computing and its impact on network virtualization. A private cloud can often benefit from versatile and scalable network configuration, so network virtualization platforms should offer some support for higher-level cloud management software. For example, VMware's NSX supports vCloud along with OpenStack using APIs. An organization with current cloud infrastructure -- or plans for future cloud deployment -- should evaluate cloud support before selecting a network virtualization product.
Another issue with NSX is poor communication between the network virtualization layer and the underlying physical network. Remember that network virtualization is supposed to bring scalability and dynamic configurability to networks, but this really requires the ability for NSX or other network virtualization platforms to know how well the underlying network and its constituent devices are working.
For example, there isn't a sound method of communicating network problems (like jitter) on one network segment to the network virtualization layer, so the network virtualization layer cannot make changes to correct the issue and optimize performance, or even report the issue to an administrator.
Network virtualization promises a new level of scalable and dynamically configurable networking that is well suited for virtualized data centers, and VMware's NSX is one platform emerging to address network virtualization initiatives. However, deploying and managing a product like NSX can have a profound effect on the data center network. IT professionals will undoubtedly want a lengthy evaluation period and follow through with large-scale proof-of-concept projects to gain experience and understand the effects of network virtualization.
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