Review: Software push the WAN performance envelope

I sometimes wonder why there aren't any movies made about IT superheroes. Sure, there's always Superman (able to leap tall buildings in a single bound) and Batman (the caped crusader), but what about WANman -- the IT superhero that accelerates high-latency traffic and saves the company from additional Internet bandwidth costs? Well, the tights and cape might not go over well (except on casual Fridays), but any IT staffer that can give enterprise users more performance is well on their way to superhero stardom.

Luckily, WANman has his own utility belt when it comes to making traffic flow faster over the WAN. A variety of hardware solutions available attack the problem using compression, TCP/IP optimization, and advanced caching techniques, all in an effort to get more out of what is available. Riverbed Technologies has long been out in front of the WAN optimization and acceleration space, helping IT staffers become superheroes in their own right. Riverbed not only addresses site-to-site WAN optimization, but now has a software client for mobile and small branch office deployments. Both appliance and client are based on the same optimization engine, and in my tests proved very adept at making WAN circuits appear cleaner and faster than they really were.

Steelhead Mobile 1.0.2

Not every situation needs -- or can justify -- a hardware-based solution. In many cases, what is needed is a software client that can provide the same type of WAN acceleration as a full-blown appliance. The Steelhead Mobile client is one of the first WAN acceleration clients for individual users. Steelhead Mobile provides all of the basic features found in the Steelhead appliance: sequenced byte reduction (SDR), TCP optimization, and CIFS- and MAPI-specific support. A central management appliance, the Steelhead Mobile Controller, manages the optimization and cache policy for each deployed end point, and collects performance metrics for reporting. The only thing missing from this release is HTTPS support.

Testing Steelhead Mobile required a slightly different test bed than what I've used in the past for site-to-site optimization. This go-round I used my trusty Shunra VE to emulate two different WAN circuits and physical connection types. One scenario mimicked a typical cable modem connection (3Mbps/512Kbps, 65ms latency) to a Dell OptiPlex client PC running Windows XP Pro. The other depicted a Wi-Fi hotspot with the Shunra emulating a DSL connection (1.5Mbps/386Kbps, 50ms) over a true 802.11g wireless link back to the same Dell PC. As in my previous tests of WAN devices, I used the Macro Scheduler utility from MJT Net to execute and time the tests.

The performance increases delivered by the Steelhead Mobile client were nothing short of tremendous. One of my tests, copying a large number of small files over CIFS, took longer than 20 minutes to complete over both WAN circuits without optimization. On the first pass with Steelhead Mobile installed, the transfer took just over 5 minutes to complete -- a 3.9X increase in performance. Other tests over CIFS showed similar results, with FTP traffic posting a 1.5X improvement on first pass. Saving a file attachment from an Exchange server showed the most modest increase, a 1.7X improvement on a cold pass.

When deploying Steelhead Mobile clients, there has to be at least one Steelhead WAN accelerator appliance at the datacenter to be the other "end point" for the optimized traffic. Another requirement is the addition of a second appliance, the Steelhead Mobile Controller (SMC), to create the optimization policies and to manage each installed end point. The SMC boosts the cost of the overall deployment a minimum of US$12,995, which includes 30 concurrent Mobile licenses. You'll want to keep that in mind when considering software client deployments. The SMC is capable of managing up to 2,000 end points on a single appliance and collects usage and performance statistics for each connected user. These stats are sent over to the core Steelhead appliance for inclusion in its overall performance reporting.

For branch offices with more than 10 users, installing one of the smaller Steelhead appliances, like the model 300 (MSRP US$9,995), makes better sense than deploying the software client. But for situations where there are a large number of users in many different locations, Steelhead Mobile fits perfectly and allows these users to see better WAN performance. Another excellent use case is the laptop user who is always on the go. Steelhead Mobile can speed up traffic to and from the central office no matter where the mobile user connects from.

In order to optimize traffic, admins create an end-point acceleration policy using the Web-based UI of the SMC. Each package defines which traffic to accelerate or ignore, any source/destination rules to apply, and whether TCP, CIFS, and MAPI optimizations are enabled. The end-point policy defines the cache size and which controller the client will communicate with. The acceleration and end-point policies are bound together in a deployment package suitable for all Windows clients from Windows 2000 to Vista -- sorry, no Mac or Linux support.