Cisco OTV: Virtually Spanning Data Centers

On Monday Cisco Systems (CSCO) will officially introduce a new technology that will make it easier to move groups of virtual machines between data centers, potentially opening new frontiers in disaster recovery, data center consolidation, and even energy management.

Rich Miller

February 8, 2010

4 Min Read
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In the beginning, there were text files. As the Internet evolved, the files moving across the network grew in size - first photos, then videos, then widgets. And now, with virtualization transforming many IT departments, virtual machines loom as the next payload networks must confront.

On Monday Cisco Systems (CSCO) will officially introduce a new technology that will make it easier to seamlessly move groups of virtual machines between data centers.

Cisco says its Overlay Transport Virtualization (OTV) solves many of the challenges that have made it difficult to shift large workloads between facilities, potentially opening new frontiers in disaster recovery, data center consolidation, and even energy management.

Tunneling Over IP
OTV is a new feature of the Nexus OS operating system that encapsulates Layer 2 Ethernet traffic within IP packets, allowing Ethernet traffic from a local area network (LAN) to be tunneled over an IP network to create a "logical data center" spanning several data centers in different locations. OTV technology will be supported in Cisco's Nexus 7000 in April 2010, and existing Nexus customers can deploy OTV through a software upgrade.

Cisco says its overlay approach makes OTV easier to implement than using a dark fiber route or MultiProtocol Label Switching (MPLS) over IP to move workloads between facilities.

"This way the server team can move virtual servers and the network team doesn't have to reinvent the wheel," said Craig Huitenga, director of marketing for Cisco's data center solutions.

Here are some details that Cisco is expected to emphasize in its announcement:

  • Operational Simplicity: Since OTV is an overlay technology, it does not require a network redesign to deploy. "With just four commands per site required, OTV can be enabled in a matter of minutes over existing networks," Cisco says. "Adding a new data center to the OTV domain is simple, configuration is only required at the new location, OTV automatically synchronizes with all other sites."

  • Transport-independent: OTV is a MAC routing scheme. Ethernet frames are encapsulated in IP packets and transported over any network that supports IP, therefore, OTV can be deployed over the Internet, private IP network or MPLS.

  • Increased Resiliency: Cisco says it has built resiliency features into OTV, which are automatically enabled when OTV is configured. These include multi-pathing, multi-homing and loop prevention. OTV also automatically suppresses flooding of unknown Layer 2 traffic. It says these features ensure that failures (such as broadcast storms or spanning-tree loops) in one data center are contained and do not propagate to other data centers.

“Moving workloads between data centers has typically involved complex and time-consuming network design and configurations,” said Ben Matheson, senior director, global partner marketing, VMware. “VMware VMotion can now leverage Cisco OTV to easily and cost-effectively move data center workloads across long distances, providing customers with resource flexibility and workload portability that span across geographically dispersed data centers.

"This represents a significant advancement for virtualized environments by simplifying and accelerating long-distance workload migrations,” Matheson added.

Terremark An Early Adopter
Among the early adopters of OTV is managed hosting and colocation specialist Terremark Worldwide, a key partner for both Cisco and VMware. Michael Duckett, Terremark’s General Manager of Network Services, says OTV has "already proven to be beneficial for the multi-site deployments of our Enterprise Cloud and the delivery of our cloud-based disaster recovery services.”

“After extensive testing, Cisco OTV appears to be a groundbreaking technology for data center interconnect, and could be a very significant contribution to the industry,” said  Duckett. “With OTV, we are able to more easily manage virtualization and cluster domains beyond a single data center, enable workload mobility between data centers, optimize compute resources across data centers, and help ensure business continuity by distributing applications and resources."

Telenor Consolidates Data Centers
Another OTV customer is Norwegian telecom provider Telenor Group, which is planning to use the new technology to consolidate 22 data centers in Norway down to four large data centers, which will operate as one large logical data center.

OTV's potential benefits extend beyond disaster recovery and server consoldiation scenarios. As we’ve previously noted, the ability to seamlessly shift workloads between data centers creates energy management possibilities, including a “follow the moon” strategy which takes advantage of lower costs for power and cooling during overnight hours. In this scenario, virtualized workloads are shifted across data centers in different time zones to capture savings from off-peak utility rates.

One likely point of debate: OTV is a Cisco technology that extends an existing standard, which is likely to be noted by rivals in the highly-competitive Battle for the Data Center. Cisco says it expects to eventually take OTV to standards bodies.

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