Both vendors claim to offer the industry's highest performance, but Silver Peak's appliance uses standard PC components rather than the dedicated hardware of Infineta's. In common with previous Silver Peak products, it targets a much wider range of applications than either Infineta or the popular WAN optimization vendors such as Riverbed.
"We aim to be able to optimize any and all links," said Damon Ennis, vice president of product management at Silver Peak in an interview. The NX-10K is aimed primarily at links between data centers involved in virtualization and cloud computing, the same market that Infineta is targeting, but it is based on the same software platform that powers other Silver Peak appliances so can also optimize links to branch offices and data centers.
Whereas Infinite uses field programmable gate arrays (FPGAs), Silver Peak uses a standard PC platform, an approach it says makes it much more adaptable. "Although FPGAs are more flexible than ASICs, they still require a long design cycle and they're impossible to virtualize," said Ennis. "Ten years ago, everything was done using custom ASICs. Now more is done in software so that you can scale up to take advantage of abundant CPUs and RAM." Its long term plan is to have WAN optimization running in virtual machines on routers or switches, an approach also championed by Cisco.
Still, scaling up isn't just a matter of adding more processors or memory. The new NX-10K is currently only available as a physical box, not yet a virtual appliance, primarily because all those CPUS and memory chips are hard to manage. For example, the box contains 16 solid-state disk drives for a total storage capacity of 1.6 TB along with multiple CPUs. Coordinating all these, so that access is fast enough to process WAN traffic without introducing unacceptable latency, is difficult--a virtual appliance version of the 10-K won't be available until the next iteration of PC hardware improves.
As well as high data rates, Silver Peak distinguishes itself from competitors like Riverbed by working at the IP layer, optimizing any IP traffic while most others target particular applications running over TCP. Ennis thinks that the growth in voice and video traffic validates this choice, as neither of these run over TCP and so are ignored by other WAN optimizers. The other vendors' main justification for this is that voice and video aren't amenable to data reduction, their technique for cutting bandwidth consumption: Reduction works by replacing large chunks of network traffic with a pointer to a local cache, something that only works if the same data is being sent repeatedly or to multiple recipients. However, Silver Peak thinks it can still apply other optimizations to voice and video.
"We want to make the IP network behave like it's a leased line," said Ellis. "We can overcome problems with packet-loss, and we're unique in that capability." For example, the Silver Peak appliances add forward error correction (FEC) to voice and video packets so that their contents can be reconstructed in the event of a lost data link. Such error correction isn't needed in TCP applications because TCP will simply re-send packets that aren't received, but the low latency requirements of voice and video mean that there isn't time for that. One downside is that FEC is in some ways the inverse of data reduction, adding redundancy and increasing bandwidth requirements, but Silver Peak thinks that extra reliability is worth the relatively small additional overhead.
Despite its general IP focus, Silver Peak doesn't try to optimize storage traffic over the cloud, an important area for other WAN optimization vendors. For example, Riverbed sees WAN storage as a big opportunity to apply its technology to cloud computing, offering the Whitewater line of appliances for enterprises connecting to storage services. "If we were to do something like Whitewater, it would compete with our partners," said Ennis. Its storage partners include Dell, which resells the Silver peak appliances, and EMC, with which it announced a cloud partnership last month.
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