The Riverbed Blog (testing)

A blog in search of a tagline

The benefits and limitations of virtualized WAN optimization

Posted by riverbedtest on November 4, 2010

Virtualized WAN optimization is not a new or unique idea–today, virtualized WAN optimization products are available from most vendors in this space.  And when considering the use of virtualized WAN optimization products, it's important to keep in proper perspective the capabilities and limitations of virtualization technology.

A key principle to remember is that virtualized editions of WAN optimization products will not resolve issues and shortcomings of the original appliance-based products.  Generally, a virtualized WAN optimization product will have the same capabilities–including strengths and weaknesses–as the original physical appliance-based product.  To illustrate, suppose you have a poorly-written or poorly-performing application hosted on the server's native operating system; hosting that same lousy application on an ESX hypervisor isn't going to make the software application's problems disappear.  The same principle applies for WAN optimization products.   

Be skeptical of any vendor that claims that the virtualized editions of their product have somehow resolved the weaknesses that plague the physical versions of the original product.  Just because a vendor's offering is virtualized does not make it more scalable or perform any better.  Per-peer data store problems do not go away just because the product is virtualized.  For example, with a per-peer data store sending a corporate email with a 10MB attachment to 100 sites still requires that 1GB (gigabyte) be written to and/or read from disk for just that one operation, regardless of whether the WAN optimization product is virtualized or not.

It's also important to realize that virtualization does incur a cost.  There is some processing and memory overhead required for the hypervisor that can negatively affect overall capacity and throughput.  In addition, in-path or in-line deployments become problematic because there currently is no way that the WAN optimization software can control the hardware platform, including in-path bypass cards.  Use of WCCP or PBR become requirements, rather than convenient deployment options.

However, as a technology, virtualization does provide some benefits and flexibility as far as deployment options, as I have noted below:

1)  Virtualization provides additional options for deploying WAN optimization into the Cloud — While it's possible to deploy physical appliances into the Cloud (Microsoft Online offers an option to deploy physical Steelheads into their BPOS-D infrastructure), the availability of software-based virtual WAN optimization offering provides additional options that were not previously available.  The virtual WAN optimization appliance can now be uploaded to virtual servers provisioned in a Public Cloud environment (IaaS).

2)  Ruggedized deployment requirements — Some environments are not suitable for the hardware platform supplied by the vendor in appliance-based WAN optimization offerings.  Issues might include deployment requirements in high altitudes (> 10,000 ft), extremely cold or hot temperatures, etc.  A software-only WAN optimization product allows the customer to install it on their own specialized hardware that does meet ruggedized environmental requirements.

3)  Import taxes — Some countries levy heavy taxes on hardware imports in order to encourage their citizens to procure hardware locally.  When deploying WAN optimization in order to support operations in these countries, importing only the virtualized software component can significantly reduce the amount of import duties that are due.


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