Peribit SR-50 Sequence Reducer review

Traffic management is one of the most common ways of getting the best value from a high-capacity WAN link, which works by controlling what goes through the connection. The PacketLogic from Netintact (see issue 122, p202) is a prime example, but there are other methods and Peribit’s Sequence Reducer (SR) takes a completely different tack.

The SR-50 is aimed at WAN speeds of up to 20Mb/sec and can manage up to 120 connections with other Peribit devices. SR products all apply a range of measures that includes MSR (molecular sequence reduction), which Peribit likens to DNA pattern matching. If it spots repeated patterns it replaces the data with labels so reducing the amount of traffic: data compression by any other name. Next comes PFA (packet flow acceleration), which increases the TCP packet receive window size to get the TCP source to send more data. Called flow pipelining, this can be used for selected applications. Functions such as SMB (server message block), which have short session times, can have responses improved as the SR can acknowledge session requests for active destinations locally. QoS (quality of service) features extend to controlling outbound traffic by guaranteeing bandwidth to specific applications and prioritising inbound traffic into four classes.

Installation is fairly straightforward. The unit’s IP address can be entered manually from the front control panel, after which you can turn to the well-designed secure browser interface. For traffic reduction you can decide whether the unit can assemble data from another SR unit and reduce it as well. You can also decide which devices it can communicate with. A smart wizard is provided to help set up QoS parameters. PFA requires information about the units performing this function and the applications to be accelerated.

For testing, we opted to look at Peribit’s reduction functions, so we used a pair of SR-50s and placed a Windows Server 2003 system with two 10/100BaseTX network cards in between. Each card was connected to an SR-50 and configured for different IP subnets, and the server had Windows routing enabled so traffic could pass across the subnets. The SR-50s were configured for the relevant IP subnets and a Server 2003 system was hung off the other side of each unit. Essentially, we had a routed link from one end server that passed through an SR-50, onto the central server, out to the second SR-50 and onward to the other end server.

To test throughput we copied a variety of files from one server to the other and monitored progress from the routing server using the Windows performance utility counter log for the network connections. For a general mixture of files we saw a slight performance improvement of about 7 to 10 per cent. Using a set of five highly compressible files produced the best results. Without any intervention from the SR-50s, the files were copied across the link in 122 seconds. But with a reduction tunnel established, the same copy took only 90 seconds, or a 35 per cent improvement in overall performance.

Unlike products such as the PacketLogic, the SR-50 doesn’t provide any security measures and is designed purely to improve WAN performance. However, it does this particularly well with a range of unique features that also includes good QoS controls. Despite the level of control, it’s pleasantly simple to install and configure.