How to Optimize the WAN for Virtual Desktops and Video Conferencing

If you have remote offices and desktop virtualization is on your IT roadmap, remember that every keystroke and screenshot must traverse the WAN. Look for optimization technologies that are designed for these predominantly unidirectional data flows.

One important component is the ability to store user-specific information caches at branch locations and then send pointers when a user requires the information. “That way, there’s less data traveling over the WAN, and response times are faster because the information is closer to the end user,” says Prashanth Shenoy, senior manager for borderless networks marketing at Cisco Systems.

This approach also frees up cache resources in the data center for use in applications with heavily multidirectional communications. “We’re seeing a number of organizations that have been thinking about deploying virtual desktops now warming up to the idea because of WAN optimization,” Shenoy says.

Video Conferencing and WAN Use

WAN optimization frees up bandwidth and improves network performance. However, for critical and time-sensitive applications such as video conferencing, more tuning of the network may be needed.

Video conferencing relies on time-sensitive transmission of data over the network. Any reduction in bandwidth allocation will result in significant deterioration in media quality — the resulting picture and audio may be so poor that they’re unusable.

Blue Coat Systems’ PacketShaper is an example of a WAN optimization appliance that’s specifically targeted for such applications. PacketShaper allows network managers to allocate priority to certain traffic over the network.

For example, a branch worker may be connected to headquarters on a 1-megabit-per-second uplink, but the bandwidth required for video conferencing is 800 kilobits per second. That doesn’t leave much room to do anything else.

If there’s no other traffic in the pipe, video quality will be excellent, but as soon as one party shares a file with another, the battle for bandwidth begins. The effect is immediate degradation in video quality.

This is where a tool like PacketShaper steps in. Network managers can allocate a high priority to the video conferencing traffic, which will ensure it gets the bandwidth it needs. If the file transfer has been deemed not time-sensitive, PacketShaper would still allow the transfer to take place but would queue it up after the conference or at a lesser speed so that it wouldn’t infringe on video quality.

“WAN optimization allows companies to really embrace video technology, which was almost impossible before,” says Mark Urban, a senior marketing director at Blue Coat. “Now, live video can be delivered with no upgrade in bandwidth.”