Cisco Fabric Extenders May Make Top-Of-Rack Switches Obsolete

The company's latest Nexus products could help companies significantly cut back on operational expenses and time spent on switch-related tasks in the data center.

J. Nicholas Hoover

January 27, 2009

3 Min Read
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Nexus 2000 Series Fabric Extender(click for larger image)

Cisco on Tuesday introduced a new series of devices, the Nexus 2000 Series Fabric Extenders, which replace switches that sit atop a rack of servers in a data center.

These new devices are analogous to thin clients, in that they get their marching orders from a larger switch and have little inherent intelligence themselves. And they could transform data center architectures by allowing organizations to do away with standard top-of-rack switches altogether.

The devices, which Cisco refers to as "rack switch extenders," play a role not unlike that of line cards in a switch chassis. In this case, the extender simply pushes all of its traffic toward an end-of-row Nexus 5000 switch, which handles all traffic management (including of features like security and quality of service), configuration, and troubleshooting and switches the traffic elsewhere in the data center.

That could help companies significantly cut back on operational expenses and time spent on switch-related tasks in the data center. In an era of virtualization and cloud computing, data centers are growing larger and more complex. With more top-of-rack switches, there's more to manage.

With Cisco's fabric extenders, however, instead of having to upgrade 10 or 100 switches when there's a need to patch software, a network admin can simply upgrade once at the larger aggregation switch. And instead of having to upgrade all top-of-rack hardware when a new important technology comes along, companies can buy one new module or switch out the larger aggregation switch at the end of the row.

Moving forward, Cisco believes extenders will become part of standard preferred data center network architectures. Instead of switches, extenders will sit atop racks of servers.

"There doesn't seem to be any architectural advantage to a standard top-of-rack switch deployment when you have this capability," said Ed Chapman, Cisco's VP of product management for data center solutions. Cisco's already recommending the first model in the line, the 2148T, instead of standard top-of-rack switches in new data centers and data center expansions.

Cisco's making a sustained push in the data center with its Nexus line as it pushes what it's calling its Data Center 3.0 vision that revolves partially around unified network fabric and virtualization. On Tuesday, the company announced two new data center switches and a power management program called EnergyWise. In the next few months, it plans to unveil a combined server and switch. All this movement puts it into heavy competition with HP, which is increasingly looking to move in on Cisco's networking prowess, leveraging its own server market position to do so.

Some of the benefits of Cisco's extender come into play in a big way in a virtualized network. In traditional data center environments, in order to handle virtual traffic, network admins have to make sure VLANs are enabled and configured properly at every top-of-rack switch. However, since the extender is little more than a dumb repeater, they no longer have to make sure that's the case. Instead, all of the VLAN policies can be put into place at the end-of-row switch.

The Fabric Extender also works with Cisco's VN-Link technology, meaning the switch is capable of delivering network and storage services on a virtual machine by virtual machine basis and applying policy so that those settings will move with VMs if they need to be replicated or moved elsewhere in the data center.

The 2148T includes 48 Gigabit Ethernet server ports and four 10-Gigabit Ethernet uplink ports. Two Web sites that have the model on sale list it for $6,900 and $7,500, comparable with some other top-of-rack switches. The extender also will eventually work with the Cisco's Nexus 7000 series switches.

About the Author(s)

J. Nicholas Hoover

Senior Editor, InformationWeek Government

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