You know what makes network administrators happy? Making efficient use of their equipment and eliminating "performance stinks" calls from end-users. Thus, investing in an effective WAN optimisation and acceleration solution such as Silver Peak NX-5500 2.0 can put a big smile on your network admin's face.

WAN acceleration and optimisation products improve WAN performance by reducing, or sometimes even eliminating, obstacles found in "chatty" applications and TCP/IP. TCP/IP is greatly affected by latency and bit errors on the link, and application protocols that require a large number of round trips (such as CIFS) can bring an otherwise fast pipe down to nearly dial-up speeds.

No longer the new kid on the WAN optimisation block, Silver Peak has substantially raised the bar with its NX-5500 appliance. Targeting WAN speeds up to DS3, it delivers superior raw performance over varying WAN conditions.

The NX-5500 optimises and accelerates not only TCP traffic but also UDP (User Datagram Protocol), a feature not common in other acceleration appliances. The NX-5500 includes Network Memory, Silver Peak's name for its caching technology, as well as a solid QoS engine. Happily, all of this can be managed via a surprisingly intuitive web-based UI.

The NX-5500 comes standard with 2TB of local storage, 50Mbit/s of WAN capacity, redundant power supplies (my units had three each) and four Gigabit Ethernet interfaces (two for management, two for WAN traffic). I like that the NICs fail-through on system failure, preventing the appliance from blocking WAN traffic.

During the past couple of months, I tested a pair of NX-5500 appliances using my Shunra Virtual Enterprise 5.0 WAN simulator and a mix of HP servers and Windows XP PCs. My test results for this release blew away all previous Silver Peak performance results. For example, with the previous version of the Silver Peak box, a "cold" pass of a single, large file copied over a T1 WAN circuit with 500ms of latency using CIFS took more than 58 minutes to complete. The 2.0 release completes the same file copy in less than 11 minutes, far outpacing the unoptimised time of nearly three hours.

By comparison, the same cold test using Silver Peak rival Riverbed's Steelhead 3.01 delivered a time of 1 hour, 32 minutes. Other tests showed similar improvements, with FTP showing the smallest amount of improvement. (Riverbed still wins that particular race.)

This time around, I added a couple of new trials to my series of tests. Among them, I employed Double-Take Software's backup and recovery utility to set up a branch-office-to-data centre replication between two Windows 2003 Servers. Without any optimisation, the replication over a T3 with 44ms of latency never surpassed 6Mbit/s. With the NX-5500 in line, a cold pass netted about 80Mbit/s, with subsequent warm passes exceeding 200Mbit/s -- all over a 45Mbit/s link. Silver Peak's Network Memory handled the high traffic speeds without any trouble.

Another test added specifically for this review was a UDP video stream. To highlight the NX-5500's UDP and QoS capabilities, I set up a video stream using the open source VideoLAN software package. On the first pass, the video played correctly on my client PC and I saw a modest reduction in traffic on the WAN. Repeat plays of the same video showed a tremendous decrease in the amount of traffic on the WAN, owing its performance increase to Network Memory. The chunks stored in the cache are encrypted using hardware-based AES-128 (Advanced Encryption Standard) and are available across all data flows and applications, regardless of direction or session.

Setting up and configuring the appliance was more straightforward than in the previous release, requiring fewer steps to create my optimisation policies and tunnel definitions. I liked that I could define different policies based on application, protocol, source and destination address, and DSCP (differentiated services code point) marking. I was able to choose the type of optimisation to employ, such as TCP and CIFS accelerations, based on the policy, or to simply pass the traffic through without any optimisation. This granularity allowed me to define one policy for my Double-Take replication system and one for scripted tests on another PC.

The reporting engine in the NX-5500 provides a good all-around view of the health and efficiency of the optimised traffic. The graph of application stats details the amount of traffic on both WAN and LAN interfaces, total bytes on both, and also the overall reduction in traffic. The tunnel statistics show the amount of traffic between a pair of appliances, the overall latency, and reduction in traffic.

The historical graphs for applications and tunnels are very easy to read, but unfortunately only store one month of data. True historical reporting requires sending the collected information to another reporting engine for analysis, such as Netflow or a CSV (comma-separated value) file.

Now available with the Silver Peak appliance is a GMS (Global Management System) that allows for centralised administration and detailed reporting capabilities. GMS users can view detailed stats on application behavior, WAN performance, such as latency and loss, and bandwidth utilisation. GMS is available on a stand-alone appliance and can handle as many as 500 NX appliances.

The NX-5500 is a smooth mix of application and protocol support, and its performance is, without question, one of the best I've ever tested. The TCP and UDP support is first rate, providing all traffic types excellent acceleration and optimisation. The reporting engine provides enough day-in/day-out information to be useful, but to really see your WAN optimisation over a long period of time requires an external reporting system. This one shortcoming aside, Silver Peak's NX-5500 should be on every network admin's short list for WAN acceleration and optimisation.


Silver Peak's NX-5500 should be on every network admin's short list for WAN acceleration and optimisation.