Overlay networks: Understanding the basics, making it a reality
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Nuage Networks announced a top-of-rack services gateway for connecting bare-metal servers to its network virtualization overlay.
Nuage's Virtual Services Gateway (VSG) 7850 is engineered to integrate with the company's Virtual Services Platform overlay. Based on merchant network silicon, the VSG 7850 has full Layer 2 and Layer 3 functionality. Like all products from Nuage, which is an Alcatel-Lucent (ALU) subsidiary, the device runs SR-OS, ALU's network operating system.
Nuage's approach to integrating bare-metal servers with its own gateway contrasts with VMware's strategy of partnering with top-of-rack switch vendors --like Juniper Networks, Brocade and Arista Networks -- to deliver that functionality to its NSX network virtualization overlay customers. Nuage said it is also working with undisclosed partners to develop so-called "white box" top-of-rack gateway devices.
Hardware gateways offer high-performance integration of non-virtualized infrastructure
While network virtualization overlays are good at automating network services for hypervisor hosts, bare-metal servers lack the software to allow them to participate in the overlay. In that case, network engineers need a services gateway to connect these servers to the overlay.
"If you're looking at deploying overlay networking in a grayfield environment, chances are there is some non-virtual infrastructure in play," said blogger Bob McCouch, a network engineer with a technology services firm. "Without some type of overlay gateway function, these devices wouldn't easily be able to participate in those overlay networks."
"Without gateways, there's no implementation, much less a migration path," said Brent Salisbury, a network engineer for the University of Kentucky. "It's a whole lot like taking vanilla IP networks and migrating them to MPLS 10 years ago. You have this juggling act where half the network is X and the other[is] Y."
Software-based gateways or gateway appliances situated further from the server rack can offer this integration, but they lack the high-performance capabilities of a top-of-rack device, which is why VMware announced so many top-of-rack gateway partners at VMworld in August. The VSG 7850 gives Nuage customers an integrated 10 and 40 Gigabit Ethernet device with 1 Tbps of capacity.
"The VSG 7850 is chock-full of 10 Gb and 40 Gb ports," McCouch said. "No virtual appliance gateway could reasonably scale to that performance." By having a hardware gateway that is fully integrated with its overlay, Nuage also offers a seamless product to customers. "I would liken Nuage's approach to Apple's with computers. VMware's approach is more like Microsoft's approach to Windows: There are a number of hardware manufacturers, and hopefully they'll all be building things just right so the software works consistently. If two of the third-party vendors begin to diverge in their implementation of some relevant detail, it could make problems for VMware in trying to keep the behavior and experience consistent."
McCouch said a homegrown gateway also gives Nuage a potential technical support advantage.
"Although VMware has gotten better with providing end-to-end support for partner-integrated solutions -- like the Cisco Nexus 1000V -- there could still come a time when they end up in a finger-pointing match with one of these ecosystem customers," he said. "If Nuage is selling a Nuage-branded piece of hardware loaded with Nuage software, the buck will stop with Nuage."
Full Layer 3 functionality for muli-tenant networks, cloud bursting
Nuage claimed the VSG 7850's Layer 3 functionality outstrips the Layer 3 capabilities of the top-of-rack gateway options presented by VMware NSX. Nuage is using merchant silicon that has a limited Layer 3 feature set, as do many of the switch vendors that have partnered with VMware. But Nuage has added some "enhancements" to the platform to extend its Layer 3 capabilities.
"This is the only gateway that has Layer 3, high-scale, multi-tenant capabilities," said Sunil Khandekar, CEO of Nuage. The VSG 7850's complete Layer 3 feature set enables Nuage's overlay to support high-performance networking for multi-tiered Web applications. It also enables hybrid clouds and cloud bursting across the WAN.
"If I am an enterprise, I have to keep sensitive applications separate in my own data center, but I also would like to burst into the public cloud," said Houman Modarres, senior director of product marketing at Nuage. "You can do exactly that with Layer 3, but you need a robust, multi-tenant, Layer 3 implementation."
"If they can drive MPLS to the gateway, that makes it a lot easier for carriers, because then the provider edge is also the SDN edge," Salisbury said.
With the VSG 7850 and SR-OS, Nuage is aiming its overlay product at ALU's sweet spot of customers: telecom service providers that are looking for network virtualization options in their data centers and cloud service offerings.
"Alcatel-Lucent has a significant install base in wireless operators and a variety of service providers, and I think this is a gateway option that had to be there [for those customers]," said Brad Casemore, research director at IDC. Those service providers have large data centers with a significant footprint of bare-metal servers, and a high-performance gateway based on ALU's technology will appeal to them, he said.
Nuage might find the enterprise a harder sell for its overlay technology, given ALU's limited presence there and the range of established enterprise vendors who are introducing overlay products, including VMware, Juniper and IBM, Casemore said.
The Nuage VSG 7850 will be generally available in the fourth quarter of this year.