Peribit's SM-250

After building a basic topology, I confirmed Peribit's out-of-box configuration claim. The unit can be quickly added and configured locally or over the wire in several ways. Basic setup via SSL or SSH took minutes, but the best was yet to come.Value Realized

Before entering anything of substance on the GUI configuration pages, I took some baseline traffic-speed measurements across my WAN link. Then I examined available combinations of compression and acceleration. It's easy to tell the box to push all traffic as fast as it can, but the biggest gains come by letting Application Flow Acceleration work its magic on some of your least-efficient traffic.

The SM-250 promised the biggest gains for us in Exchange, CIFS (Common Internet File System, Microsoft file transfers) and Web traffic. By employing a fast local drive and a combination of caching, requesting data blocks in advance of the application's own requests, and HTTP "prefetching" for varying content, the SM-250 made sure traffic transferred several times faster than the link could do on its own.

All traffic routed through my SM-250 tunnel traveled fast enough to impress, and I was pleasantly surprised by some huge individual gains. For example, before acceleration, one FTP transfer took 74 seconds; with acceleration turned on, less than 2 seconds; and after the SM-250 learned enough about the traffic to only send changed parts of the file, or "delta changes" through the entire link, the transfer speed dropped to less than 1 second.

The effect was duplicated with Exchange traffic and CIFS file transfers. Transfers that natively took minutes to traverse the WAN whizzed through the accelerated link in seconds. One pass showed that my 1.544-Mbps T1 was acting better than a 45-Mbps DS-3 line. Got voice? Throw some QoS into the mix using the wizard utility or by assigning bandwidth or weights to traffic classes manually. Also, the device's congestion control increases network efficiency by not letting available space in the link saturate.

The Rest of the Story

The SM-250 comes ready to dazzle, but administrators may want more functionality when characterizing traffic. Reporting is granular enough, but exporting reports is limited to a single Web page view, CSV files or screenshots. But these criticisms are petty compared with the SM-250's performance gains--it will kick your slow WAN links up several notches.

Lee Badman is a network engineer at Syracuse University. Write to him at [email protected].