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Virtualization & Communications


Virtualization. Big word, big concept. It’s an even bigger value for the data center. Yet if you ask five experts to define it, you’ll get 10 answers, and that’s on a good day. In the broadest sense of the term, virtualizationwhether it involves servers, storage, or even networks themselvesis simply a way to maximize hardware and software investments by grouping them into logical structures divorced from their physical boundaries.

For instance, to save space and money, most data centers condense dozens of servers onto a single physical box using VMWare, XenSource, and other server virtualization software. Some data centers condense dozens (or even hundreds) of storage tools into one neat, logical unit through storage virtualization. No matter where those tools are, they appear as one entity through the wizardry of software, the simpler to manage and manipulate.

But there’s another level of virtualizationvirtualization at the communications layer, or virtualization of networks and network servicesthat lets admins leverage whole networks for maximum effect. We’ll take a look at its past, present, and future.

The Past: VLANs

Of course, the simplest form of network virtualization is VLANs, a strategy that’s so well-known it’s nearly commonplace.

A VLAN, or virtual LAN, is a group of computers that believe they’re attached to the same physical network, no matter where they are. They behave as one logical unit despite their location, making it simpler to move machines. Just unplug a box, haul it down the hall or across the street, and plug it back in. The 802.1Q standard that governs VLANs lets you drag a box from port to port without changing its MAC or IP address, a boon in an office world defined by cross-enterprise teams and ultra-max mobility. (Of course, the advent of DHCP took some wind out of VLAN’s sails because DHCP reassigns IPs on the fly.)

But VLANs offer more than just movement. They let you parse network traffic by type, putting VoIP traffic on one logical network and Wi-Fi on a second (a common strategy in many small to midsized enterprises). Yes, data can leak from VLAN to VLAN, but the logical structures are cleaner and even more elegant than merging all your traffic together.

Yet for all these benefits, the real value of virtualization at the communications layer lies in technologies just coming into voguevirtualization in the present tense.

Here & Now: Service Virtualization

You may already have equipment that lets you virtualize key network services. Take Cisco’s Catalyst line, whose 6500 switch offers an Application Control Engine (www The Engine has load balancing, security features, and data packet inspection, and according to Cisco’s John Yen, it lets you virtualize them all.

“Rather than having to rack up new hardware physically for each new application, all you have to do is go into this blade, do a few configuration changes, and now you can basically apply security services, as well as load balancing services” without painstaking, one-by-one setups, Yen says. The Catalyst 6500 also offers “contexts,” which, according to Yen, is “basically a set of different services that you can activate per application. If you turn on a new application, you can say, ‘This application needs these three services; it needs load balancing, security, and data packet inspection services,’ and within that one context you can activate multiple services.”

The result? You can “partition” a switch with up to 250 contexts, much the same way you partition a server. It results in fewer hand-offs among IT groups, which in turn cuts deployment lags because it takes longer to pass items through a process chain than it does to configure them on the fly. Yen says that Cisco used the technique in its own data centers and reduced deployment times by up to two-thirds.

But Cisco is not alone in seeking to virtualize key network functions. Software from Infoblox cuts network management overhead by giving admins the power to virtualize key protocols such as DNS, DHCP, and RADIUS and better manage IP and MAC addresses, user credentials, and other key data across LANs. Called NIOS, the software runs on Infoblox appliances such as the DNSone with Keystone, which, among other features, offers virtual DNS and enhanced Bind views (

On a larger scale, Marconi's ASX4000M switch router offers up to 900,000 virtual circuits; the BXR48000 offers more than 2 million ( (A virtual circuit is a device connection that mimics a direct connection, even though its true physical path may take it over many hops or nodes.)

The Future: The Intelligent Network

So what’s the future of network and internetwork virtualization? It might look like The High-Tech Campus Eindhoven in the Netherlands. The Campus supports the research arm of Philips Electronics and spans over 20 acres with 30 buildings, with office space, clean rooms, labs, and 5,000 workers from a whopping 50 countries.

According to Patrick Stemkens, Eindhoven’s CIO, it’s also an “open research environment” where the pace of research speeds up when researchers from different teams, buildings, and even companies put their heads togethertheir heads, and their data. To maximize sharing, Eindhoven’s physical networks were virtualized into logical structures that carry voice, collaboration, and security traffic, governed by VRF (virtual routing and forwarding) and service virtualization. All of it lets researchers roam freely, plug into colleagues’ systems, and share data through IP telephony, TV, and mobile tools without interruption.

Because the Campus infrastructure is defined more by logical networks than physical ones, it lets the IT group quickly provision startups, which not only promotes new research but makes the workand livesof network engineers simpler.

Or to use Yen’s words: “It’s not just about how fast your network can work, but how fast your people can operate.” Hence the future of virtualization could mean something that still eludes today’s data centers: networks where people move as fast as data itself.

Read the original, here.

Published Friday, October 20, 2006 6:57 AM by David Marshall
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