WAN optimization appliances improve use of existing bandwidth by transparently reducing the amount of traffic pumped into the WAN. They smooth over TCP shortcomings via better window management, for example. They optimize chatty upper-layer LAN protocols like MAPI, HTTP, and Windows file sharing.
We surveyed 486 IT professionals who use or have evaluated WAN optimization appliances to find out how they perform. Not surprisingly, Cisco Systems gets invited to the WAN optimization party by nearly half (49%) of respondents, largely because of its ubiquity in enterprise data centers. Riverbed is a close second, with 40%, handily beating out the rest of our field. Citrix, Juniper, Blue Coat, and F5 round out the top six.
Blue Coat, Cisco, and Riverbed have the highest rankings based on 10 evaluation criteria, including product performance and reliability (see chart).
While Blue Coat and Riverbed lead on performance in our survey, you generally won't find much variation in raw deduplication rates among products. Where you will find differentiation is in how much data the appliances can process on the LAN side. Vendors tend to scale their appliances based on WAN capacity, from T1 speeds to 1 Gbps and beyond. This scaling doesn't reflect network performance as much as the size of the internal storage array containing the deduplication data set, the number and types of CPUs, and RAM. The larger the WAN pipe and the more capacity that's consumed, the larger the disks must be to build an adequate dictionary. And, of course, adequate CPU and RAM are needed to be responsive.
Automatic application detection and detection within HTTP are the WAN optimization features that are particularly important as companies "webify" more applications and adopt VDI. Blue Coat and Citrix have long touted their automated application discovery features that can poke into oft-used protocols, such as HTTP, and differentiate Outlook Web Access from PeopleSoft and act accordingly. Citrix, in its quest to move everyone to VDI, has a leg up on optimizing its own popular VDI protocols.
Not to be left out, other WAN optimization vendors say their products can perform some VDI optimization as well, though they're usually limited to TCP optimizing and packet coalescing. While many optimizers offer manual configuration, where administrators specify the server IP address and other details, having built-in detection means one less task set added to your change-control processes. This is a key distinction to look for when shopping for a WAN optimization product.
Most respondents using WAN optimization are happy with their appliances and aren't actively looking to replace them. Still, vendors shouldn't become complacent. Respondents say advances in technology and a more cost-effective offering could spur them to kick out an incumbent.