Defining a strategy for using virtual switches in your network

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Defining a strategy for using virtual switches in your network

What's your virtualized switch strategy for your environment?SMB Managed Switches Server virtualization is obviously here to stay. If you are a networking professional working in the enterprise who hasn't had to deal with an environment that has multiple virtual machines at this point, I'd argue that you should be looking for a new environment. Few environments exist where virtualizing support servers using DNS, LDAP or DHCP doesn't make sense. As virtualized server environments mature, so grows the virtualized networking environment that accompanies them.

For most environments, it's inevitable that the number of physical hosts running virtual machines and their virtual switches grows from one server to two, three or dozens of physical servers, for that matter. If your plan is not well thought out, you could end up with an environment with dozens of basically dumb switches in your data center that don't tie into your network management infrastructure and tools. This can make troubleshooting a nightmare or impossible. What happens when you need to get Cisco Netflow data from one of these mystery devices? To what IP address do you point your tools, and to what ports are the virtual machines connected? What happens if a virtual machine moves from one host to another?

You can treat this blog as an introduction to virtual switches for us networking guys that don't get involved in x86 server virtualization. We'll take a look at four major hypervisors and their switch options. The four hypervisors are VMware vSphere, Microsoft Hyper-V, Citrix XenServer and Kernel-based Virtual Machine (KVM).Virtual switches basically fall into two categories -- distributed and non-distributed. Non-distributed switches are virtual switches that have many-to-one switch-to-server relationships. Distributed switches may have a one-to-many switch-to-server relationship. Non-distributed switches are therefore simpler and have fewer features than distributed switches. Non-distributed switches don't take much thought from a hypervisor management perspective to implement. If you are in an environment where there was no collaboration between the networking team and the server team, there's a pretty good chance you have a bunch of non-distributed switches in your environment. The worse scenario is that you have a bunch of distributed switches with no integration with your physical network. Not all configuration standards may apply to the virtual distributed switches, but they should be considered when creating the baseline configuration.