Virtual network switches add scalability to server virtualization

With virtual switches, Cisco Systems and now Arista Networks are trying to clear the networking bottlenecks that occur when enterprises do large-scale server virtualization.

Cisco's Nexus 1000v aims to give the networking team control over virtual infrastructure management. Meanwhile, Arista's vEOS product, announced today, integrates with VMware's existing technology and promises to be more appealing to system administrators who want to bypass network administrators when managing virtual environments.

One of the key networking challenges with server virtualization is the management of virtualized network and security profiles, as well as virtual machine configurations, as they migrate across physical hosts. Performing that task in a scalable way is tough and often prevents enterprises from taking their server virtualization efforts beyond server consolidation and into dynamic resource allocation. This is very much a networking problem, and companies like Cisco Systems and now Arista Networks are trying to solve it.

Technologies like VMware's vMotion and vSphere make it easy for virtual machines to migrate from one physical host to another as needed and for applications to scale up and down by combining the resources of multiple physical hosts. However, a networking bottleneck occurs when enterprises try to create such a dynamic virtual infrastructure. Network and system administrators struggle to make sure that the virtual network and security settings and profiles migrate with the virtual machines as they traverse across physical hosts. VMware and other hypervisor vendors offer some form of virtual switching technology that allows server administrators to manage the virtual network and security settings within the physical hosts, but typically these virtual switching products don't scale up to the level that some enterprises need.
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"If vMotion moves a workload from one machine to another to balance out load or to recover from failure, that's great," said Joe Skorupa, research vice president with Gartner. "But if you have to manually go back and reconfigure the switches, that's not so good."

These networking bottlenecks often limit the extent of server virtualization that can occur within an enterprise.

"Having spoken with customers about this problem going on three years now, this has been one of the key points with trying to get past the 15% to 20% [ceiling] of your servers being virtualized," said Rob Whiteley, vice president and research director at Forrester Research. "At a small scale, you don't bump into networking problems. But typically, around 15% to 20% of your production servers going virtual, you're going to start having issues."

This problem of scale motivated Cisco to release the Nexus 1000v earlier this year. This virtual switch actually replaces VMware's vSwitch technology and manages the virtual network and security connections that take place within virtualized servers. It also gives network administrators a familiar interface for managing those connections, which are quite often handled by server administrators without the network administrators' knowledge.

Now, startup switch vendor Arista Networks has introduced its new virtual Extensible Operating System (vEOS). In some ways similar to the Nexus 1000v concept, Arista's vEOS is actually a software image of the EOS operating system that runs on all of Arista's physical switches. It functions as a virtual appliance, running inside the physical server that is hosting virtual servers. It doesn't replace VMware's vSwitch technology. Instead, the vEOS works with it, making vSwitch more scalable and familiar to network administrators, who find many of VMware's products too foreign.

"Clearly, the virtual switch that comes with VMware infrastructure is good, but it won't scale to the data center networking that people need," Whiteley said. "I think what Arista has done is very elegant from a software engineering perspective. They're not beating their chests on their ASICs and their hardware. They're appropriately spending a little more time on the concept of a truly stateful operating system."

Systems vs. networking: Battling for virtual network management control

The difference in approach between Arista and Cisco is also indicative of a quiet struggle that has been going between system administrators and network administrators for control of switching and management in virtualized data centers.

"Cisco wants to extend [its] control all the way up into servers and take control of them," Skorupa said. "Arista is certainly aligning [itself] with VMware."

Arista's vEOS may be based on the operating system that runs on its physical switches, but Skorupa believes the vEOS will go largely unused by network administrators. Instead, system administrators will have more of a use for it, he said. Systems guys have been managing switching within virtual hosts for a few years now, much to the chagrin of network administrators. The vEOS will allow them to continue on that path.

"It's the battle we've seen brewing and going on quietly in the background for the past year or so, which is: Who is in control?" Skorupa said. "Is the network guy in control when he puts the Cisco virtual switch into the VMware server? Or is the server guy in control when he uses the VMware embedded switch and then integrates with whichever networking vendor [such as Arista] he chooses?

Server administrators usually support virtual switching products that enable them to manage the process without relying on the networking team, Skorupa said.

"It creates political problems for the network guys," he said, "because they lose their influence and control."

Doug Gourlay, Arista's vice president of marketing, emphasized that the vEOS is aimed squarely at network administrators.

"The server guy can access vSphere with his familiar Web interface," Gourlay said. "The network administrator gains CLI and SMNP."

A new breed of administrator for the virtualized environment?

The so-called war between server and network factions in virtualized data centers may ultimately give way to a new hybrid data center role, a concept Whiteley describes as the virtualization administrator. These admins will be mostly server-oriented but will have strong storage and networking skills as well.

"The $5,000 price point [of Arista's vEOS] is the perfect price point to attack these virtualization administrators because they're going to be able to quickly solve the problems they have, which is scaling the network," Whiteley said. "At the same time, I don't think it completely alienates the networking team because it puts a decent working product in there that they will be able to use. Now, there will still be politics at play here because if the server team keeps procuring its own network infrastructure, even in a virtual form fact , let's hope they're looping in the network team. I don't think that's Arista's problem to solve. That's an internal challenge that companies have to work through."

Arista's vEOS comes free of charge with the purchase of an Arista 7000 switch. A scaled-back version of vEOS that addresses only visibility and troubleshooting is available free to anyone for a limited time. The full network configuration version is priced at $5,000.

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