VMware's vNetwork Distributed Switch explained

By Bridget Botelho
Wednesday, 27 May, 2009

VMware's vNetwork Distributed Switch is quite possibly the most badass new feature of the 150 new technologies in VMware vSphere, which became available last week.

Included in vSphere 4 (or VMware Infrastructure 4) Enterprise Plus edition, the feature provides a centralized point of control within VMware vCenter Server for cluster-level networking so administrators don't have to provision network configurations for each virtual machine (VM) individually.

"So instead of going to each individual server and making sure the connections are exactly the same, vNetwork sets up cluster-level network configurations across many servers, making configurations quick and very simple," said Leena Joshi, a product manager at VMware.

The feature is immensely useful to network administrators, because tools like Distributed Resource Scheduler (DRS) that move VMs from one server to another work only if every host server has the same port group and network connections, and getting all the servers configured this way is a real time suck, Joshi explained.

Increasing admin productivity

At a recent VMware User Group meeting, VMware engineers said the vNetwork Distributed Switch (VDS) is "one of the most exciting new technologies in vSphere" because of the time-saving benefits it offers administrators. VMware users at the event showed enthusiasm over the distributed virtual switch technology, and that excitement is evident on the blogosphere as well.

Rick J. Scherer, a systems administrator and vExpert/VMware Certified Professional at the San Diego Data Processing Corp. and the author of the VMwaretips.com blog, has experimented with vNetwork Distributed Switch in his test and development lab and is pleased with the results.

"I can really see how it will increase productivity, especially when deploying new ESX hosts to an existing cluster," Scherer said. "Instead of having to create individual vSwitches and port groups on each ESX host within a cluster, you only create it once and every host within the cluster effectively "joins" the [vNetwork Distributed Switch], made available by the cluster."

The technology works by abstracting configurations of individual virtual switches (click to see Figure 1) and enabling administrators to manage, provision and monitor network configurations from vCenter.

Eric Sloof, a VMware certified instructor and blogger, wrote about setting up VDS, and the process appears pretty straightforward. Administrators can use the Create vNetwork Distributed Switch wizard to create a distributed switch on a vCenter Server. Once the switch is installed, they can add hosts, create distributed virtual port groups -- a task that specifies port configuration options for each member port on the vNetwork -- and edit vNetwork Distributed Switch properties and policies.

Each distributed switch supports up to 32 ESX host servers, and it works on any kind of x86 server and networking equipment, Joshi said.

A major benefit of the vNetwork Distributed Switch is that it allows customers to replace the standard virtual networking programs such as VMnet with other third-party tools, the first being the Cisco Nexus 1000V virtual switch. This is good from a comfort standpoint, because it lets admins use their familiar interfaces and features, Joshi said.

With vNetwork, the Nexus 1000V acts like a standard virtual switch, only better. It integrates with services such as Session Initiation Protocol, Access Control Lists, and networking Quality of Service, add has management and visibility enhancements.

"The switch management is taken out of the vSphere client and put back into the network engineers' hands by allowing them to manage with [the Cisco Nexus 1000v management interface] Virtual Supervisor Module," Scherer said.

Gaining better insight into VM traffic

Combining vNetwork with Cisco Nexus gives virtualisation users deeper visibility into VM traffic than they had with Nexus alone. That allows them to track data movement within VMs, Joshi said.

"Before, a Cisco network admin had visibility up to the host level, but limited visibility into VMs. Now they have host-level and individual VM-level visibility into their environment, using their familiar tools and management controls," Joshi said. "It is like they have x-ray vision and can watch all of the VM movement."

The vNetwork Distributed Switch also maintains network runtime states for VMs as they move across multiple hosts with VMotion, enabling inline monitoring and centralized firewall services, which makes network security much easier to implement, Joshi said.

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