Cisco Pushes Groundwork for Greener Networks - Page 2

Page 2 of 2

One of the key new mechanisms in the Nexus updates to help datacenter consolidation is a new take on network virtualization, called Virtual Device Context (VDC).

"Virtual Device Context allows a physical switch to logically be carved into four logical switches with complete isolation and security," Velaga said.

The benefits include a greater level of granular control for large networks, Cisco said.

VDC is the opposite approach of what Cisco rolled out in 2007 on its Cisco Catalyst 6550 switch, with its Virtual Switching System (VSS). VSS enables two physically separate Catalyst switches to be combined into one virtual switch.

Cisco and other networking vendors for years have enabled what's known as "virtual LAN," or VLAN , as a way to break up one physical network into multiple virtual networks.

Velaga said VDC solves an access control issue that could come up with VLANs: If you run a switch with VLANs, all line cards on the same physical switch see the same VLANs.

"So say a customer has 256 MAC addresses. All line cards would see the same addresses since they are all forwarding as if it was a single switch," he said, adding that the setup still enables admins to isolate traffic across the network.

But with VDC, "you can carve out the switch into four separate logical switches and each one sees a different set of addresses," he said. As a result, with VDC, one logical switch could be restarted or shut down without impacting traffic on the other logical switches.

Direct memory access via Ethernet

Cisco is also using the Nexus update as an opportunity to further consolidate the capabilities of Ethernet as the primary fabric for datacenters. In particular, the new Cisco RAB technology -- short for RDMA Accelerated Buffer -- brings Infiniband's low levels of latency to Ethernet.

"We're taking advantage of the lossless Ethernet capabilities in our Nexus portfolio and combining with our software, so Ethernet host adapters can run direct memory access," Velaga said. "So now you can get the same low latency of Infiniband on Ethernet infrastructure."

While Cisco is preaching the merits of consolidation to its customers and the market, Velaga added that Cisco itself is benefiting directly from its technology.

Velaga claimed that Cisco's WebEx infrastructure has now been consolidated with unified fabric and VDI to consume fewer resources. In fact, Velaga claimed that as a result of the consolidation Cisco has been able to deploy up to 30 percent more servers in its WebEx data centers.

"In these economic times when customers can't come up with outlays for new datacenters instead they can re-use their existing facilities by freeing up network resources that were otherwise consumed with network devices," Velaga said.