Expand Networks Accelerator 6910 review

Optimising the WAN is fast becoming a critical consideration for businesses implementing a distributed network, and Expand Networks offers an impressive family of appliances for the purpose. On review is the Accelerator 6910, which targets core data centre services. For testing, we used a pair of 6910s, but remote offices can choose from plenty of lower-cost and lower-specified models. All run the same code that delivers the company’s Compass platform, offering the full gamut of WAN optimisation, Layer 7 application inspection, acceleration, WAFS (wide area files services), QoS and security. In common with all other solutions, the appliances function as transparent TCP proxies that intercept and optimise all TCP traffic.

Every vendor claims to offer something unique – with Blue Coat’s SG family it’s object caching, while the Expand solution has the ability to become part of a Windows domain, allowing greater security to be extended to CIFS/SMB file operations. Much of the competition use CIFS spoofing, where the appliances terminate and respond locally to connection requests. Not so with Expand, as this approach allows it to protect domain integrity and other functions such as SMB signing. Furthermore, if the WAN goes down, the appliance retains locally cached read-only copies of files, but it also stores domain information for users that were authenticated while the WAN was up. However, unlike Blue Coat, the Accelerator products can’t currently optimise HTTPS traffic.

For testing, we used the Labs-resident Network Nightmare WAN simulator (www.networknightmare.com) set up in routing mode and configured for a 2Mb/sec E1 WAN link with 40ms latency. We placed a 6910 on one side and at one end added a Windows Server 2003 system configured with Kerio’s MailServer 6. To represent a remote office, we used another 6910 appliance on the other side of the simulator and connected a Windows Server 2003 system to act as a client. A 4.8MB PowerPoint presentation was used to test a variety of scenarios.

With optimisation turned off, remotely opening the file at the client using PowerPoint took 41 seconds and saving a small modification to the server took 47 seconds. With Expand in action and the file cached, these times were reduced to only 3.5 and 6.5 seconds. Mailing the file as an attachment from the client to the server with no optimisation took 3mins 7secs, while receiving the same file on the client took 41 seconds. With the file cached, the Expand appliances reduced these times to only 4 seconds and 4.5 seconds. Simple file-copy operations also saw significant improvements, with the presentation copied from client to server and back again in 24 seconds and 28 seconds respectively without optimisation, but only 1.5 seconds with optimisation activated and the file cached.

Expand has been in this game longer than most and it shows. The 6910 delivers the WAN performance improvements we’d expect to see and offers a wide range of traffic management and security features at a reasonable price.