Review: Riverbed closes the WAN gap

Riverbed Steelhead with RiOS 7 takes a huge bite out of UDP, video, and VDI traffic over the WAN, adding to its excellent TCP and file access optimizations

InfoWorld |

"I'll just get a faster pipe" is an appropriate response to many network problems, but a slow WAN isn't one of them. Surprising though it may seem, a bandwidth upgrade will often do nothing to improve application response times or speed file transfers over a wide area network. To squeeze better performance out of a WAN, you need to resort to tricks -- tricks that only a WAN optimization solution such as Riverbed's Steelhead can provide.

Some simple math shows why. WAN performance is bound by two factors, TCP window size and network latency, that have almost nothing to do with the bandwidth of the link. It is easy to calculate the maximum possible throughput of a WAN link by using the following equation:

(TCP window size in bits) / (latency in seconds) = maximum bits per second

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For example, a 1Gb Ethernet link from St. Louis to Miami with a latency of 50ms and the standard 64KB TCP window size gives us a maximum possible throughput of 10.49Mbps -- and a bigger pipe wouldn't change a thing. Even if the pipe were a mythical 100Gb link, users would still see 10.49Mbps (and a lot of money wasted).

In order to "fill the pipe," either latency has to decrease or TCP window size has to increase. Riverbed's Steelhead can do both and a lot more. This combination of hardware and highly specialized software plays tricks with TCP window sizes, compresses data to squeeze more onto the wire, removes redundant data bits through deduplication, and uses application-specific optimization engines to reduce overall response time.

With the Riverbed Optimization System (RiOS) version 7, this feature-rich platform gets even richer, adding UDP optimization, IPv6 support, video stream splitting, and enhancements for remote desktop and VDI (virtual desktop infrastructure) environments. Riverbed continues to enhance its TCP optimization, and the inclusion of UDP closes a gap with competitors. Performance proved top-notch, as always, and the reporting engine gives admins all the information they could want.