What Is WAN Optimization, and How Can It Help You?

Updated: August 07, 2009


It's not unusual for SMBs to operate from multiple locations. Some of those locations may even be overseas, making such companies multinational SMBs. Other locations may consist merely of people working out of their home offices. WAN (wide-area network) and related communication technologies are key to making such arrangements work. But several cost and performance issues keep them from working as well as they should. An emerging technology called WAN optimization addresses those issues.

WAN optimization uses appliances located in a company's different sites. Suppliers range from smaller vendors like Blue Coat Systems, Citrix Systems, and Riverbed Technology to large manufacturers like Cisco Systems and Juniper Networks. The appliances use a number of techniques to process the IP traffic traveling between the sites over the company's WAN. The techniques cut the bandwidth needed and increase the speed and responsiveness of the connection. This brings numerous benefits, from slashing the cost of inter-branch communication to improving its effectiveness in various ways. The combination often lets companies work in ways that would otherwise be impossible. Not all solutions, however, use all of the techniques, so it's necessary to confirm with vendors just what their appliances can and cannot do.


A key WAN optimization technique is caching, which puts copies of files in different locations. That makes it unnecessary for users to fetch files 20 MB to 100 MB or more in size across a WAN connection whenever they want to use them. And when someone changes a file, the system doesn't need to retransmit the entire file to the caching locations — it only sends the parts that were changed. It also compresses files so there is less data to transmit and store. The practical result is that users can often fetch in 30 seconds or less files that used to require 60 minutes to obtain.

A second technique is protocol optimization, which cuts the amount of electronic chit-chat between sites. Communication protocols such as TCP send several messages back and forth when they're working to ensure that each end knows what the other is sending and has received. That results in a lot of time spent waiting for confirmation rather than actually transmitting data. To make matters worse, each chunk of data transmitted is relatively small. Protocol optimization drastically reduces the number of messages necessary and thus the transmission delays, which increases both the transmission speed and the responsiveness of the links. Some WAN optimization solutions can similarly speed up the response of various applications themselves, which can be quite chatty and inefficient as they access email, database or other files.

Some solutions can also manage bandwidth or quality of service. For example, they can put limits on how much bandwidth certain kinds of resource-greedy applications can hog. Conversely, they can guarantee that other types of applications always have access to a certain amount of bandwidth. Or they can just ensure that some types of data traffic have priority over others. Such capabilities make it easier to run real-time, delay-sensitive applications such as voice and video over corporate networks.

Measurable Benefits

The most easily measurable benefit of WAN optimization technology is the savings on communication costs it generates. Vendors say their gear can cut the bandwidth necessary between branches by 50 percent to 95 percent or more. Starting prices on appliances range from $2,000 to $6,000 and up. Thus in some circumstances, the gear can pay for itself in as little as 18 months, vendors claim. Savings will be particularly large when some of the connected sites are in overseas locations with high communication costs. Alternatively, optimization can free up existing inter-branch bandwidth for other purposes. Combined with the QOS capabilities, for example, that may allow the addition of inter-branch IP telephony or video conferencing.

Another measurable benefit of WAN optimization is the application consolidation that it allows. Rather than having individual e-mail servers in each location, for example, companies can use one centralized one. Likewise with file and print servers, and other more specialized applications and databases. Such consolidation can significantly reduce the cost of equipment and software a company needs, as well as the amount of trained IT staff it must employ.

WAN optimization also makes remote backup of data easier. Backup is crucial for disaster recovery, ensuring that businesses can continue to operate in case catastrophe wipes out their corporate data at one or more locations. The same techniques that reduce bandwidth requirements and data volume allow companies to back up their data in one or two locations over the corporate network, rather than doing so manually in each location. That can produce big savings in backup equipment, while making it unnecessary to assign someone at each office to feed tapes into said equipment on a regular schedule.

Transforming Operations

The powerful capabilities of WAN optimization systems can help some companies literally transform their operations. Businesses that routinely deal with huge electronic files, for instance, face inherent limitations on what they can do. If they have employees in a number of locations, those employees have a hard time collaborating when collaboration requires working on the same electronic document. When one employee makes changes and sends it to others for their input, it may take an hour or more to get the revised document back. Thus a few minor changes can eat up most of a working day. Use of WAN optimization, however, allows employees in different locations to make collaborative changes almost in real time. That in turn allows companies to take advantage of talent wherever they can find it. It even makes possible 24-hour operation, with teams in different time zones around the world working on projects around the clock.

But while companies that regularly deal with large files, such as architectural and engineering firms, are a natural fit for WAN optimization, vendors such as Blue Coat and Riverbed say their customers include every type of company. A lot of businesses, for instance, live and die by huge, centralized Excel spreadsheets. Others regularly send large numbers of bulky Microsoft Office and other documents among their far-flung staff. And many have centralized databases or applications that employees may avoid using because it's easier to provide crucial information to the head office by phone than it is to update a database via a poky file transfer.

Vendors' Offerings Vary

As noted, vendors' products vary in the number of capabilities they offer. Some focus mainly on accelerating all traffic between sites, while others have the ability to treat different types of traffic and applications in different ways, providing more flexibility and customization.

Riverbed's flagship offering is its Steelhead line of acceleration-oriented appliances. They range from the low-end 250-Series models, with 40-GB data storage and the ability to handle 1 Mbps WAN connections, to the 6050 Series with 3.5-TB storage and 310 Mbps WAN capacity. Riverbed also extends its technology to home workers, offering a so-called "mobile" software application that runs on windows PCs and works with its Steelhead appliances. The app provides employees working from home the same WAN acceleration benefits without requiring a separate appliance.

Blue Coat categorizes its ProxySG line of appliances by the number of concurrent users they support and numerous other factors. The low-end 210-5 product handles up to 10 users, while the 210-10 handles 50 users and the 210-25 allows unlimited users. The 510-5 product permits 50 users to access all the appliance's features, including those that set different policies for different kinds of traffic, or 200 users using the basic acceleration capabilities without the additional features. The 510-20 is for 300 users accessing the full range of features or 1,200 using only the basic capabilities, while the 510-25 permits unlimited users. There are also 810 and 8100 models which mainly target large corporate datacenters.

Juniper Networks offers what it calls the WX and WXC series of application acceleration platforms. The WX series ranges from the WX15 that handles WAN speeds of up to 1 Mbps and six "tunnels," or links to other sites with all features enabled, to the WX100 for up to 20 Mbps and 105 tunnels supporting all features. The WXC series starts with the 250 model for up to 2 Mbps and 10 tunnels, with the high-end WXC1800 handling up to 45 Mbps and 140 tunnels.

Citrix Systems offers a WAN optimization product it calls the Citrix Repeater (formerly known as WANScaler), which is also available bundled with Microsoft Windows Server to provide branch offices with functions such as file and print authentication as well as other network services. Cisco Systems provides a comprehensive enterprise-level solution it calls Wide Area Application Services, or WAAS, that works through existing Cisco routers and infrastructure.


The most important step in choosing a WAN optimization solution is deciding what you want it to do for you. If your goal is straightforward cost savings, you have several calculations to make.
One is how much you will be able to cut your bandwidth costs, and perhaps your phone bill as well if the solution lets you move to inter-branch VoIP. The other is how much you can save by consolidating or centralizing various IT applications and functions.

Consolidation can help cut both equipment and personnel costs. When calculating equipment savings, you'll have to take your existing infrastructure into account. If you've already bought several servers and other gear for your various locations, WAN optimization won't save you much unless you turn around and sell that equipment. But if it helps you avoid buying hardware and software you would otherwise need as you expand your operations, optimization can produce considerable savings.

Calculating the value of productivity gains is trickier. In some cases, WAN optimization will let you do things you couldn't otherwise do, such as set up global collaboration. In other cases, it will simply help you get more done in less time. Either way, you may or may not have a clear idea of what those less-tangible benefits are worth. If you don't, consider hiring a consultant to analyze your business processes and estimate the bottom-line value WAN optimization will bring you.

In talking with vendors, remember that all WAN optimization solutions are not equal. Some do little more than accelerate all WAN traffic between sites. Others give special treatment to particular types of applications and traffic, providing benefits that, while hard to quantify, may make a huge difference in how you run your business.

The best fit will naturally be the one that focuses on the applications you use. But even if all a particular solution offers is acceleration, the resulting savings may make it worth the cost.

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