As everyone is aware, in remote user situations or in installations where corporate branch offices may be located in remote facilities, WAN bandwidth is at a premium. And, in many cases IT departments struggle to make the most efficient use of the available bandwidth because of WAN latency. Citrix WANScaler and Branch Repeater are proven networking appliance solutions for compressing and accelerating traffic across the WAN, and has aided many customers in increasing the overall efficiency of their enterprise networks.

However, questions have always existed regarding ICA performance across the WAN. Although the ICA protocol is very efficient by design, it has been questioned whether ICA traffic could be accelerated or compressed even more by WANScaler, making even better use of limited bandwidth situations.

With help from customer input, Citrix has developed and implemented new technology which greatly improves performance of ICA over the WAN. With upcoming releases of XenApp (in conjunction with future firmware release for WANScaler and Branch Repeater) partners and customers will be able to deploy hosted XenApp applications over the WAN with more predictability and higher performance for end users. By taking advantage of the newly developed compression algorithms in WANScaler and Branch Repeater, designed specifically for ICA, XenApp traffic across the WAN will be greatly enhanced.

Recently, Citrix performed an in-house performance assessment in order to test the upcoming ICA compression enhancements. The purpose of this project was to conduct an assessment of XenApp performance (with and without WANScaler) in order to compile performance data reflecting the increased performance of the latest enhancements. This, in turn, would show the advantage and the increased performance of a network infrastructure that includes either a WANScaler or Branch Repeater in conjunction with a XenApp server farm.

The key findings from the assessment showed impressive ICA performance increases when using WANScaler in conjunction with XenApp servers. These findings include increases in overall amounts of data sent over a fixed-size WAN link, increases in compression rates of ICA traffic, and reduced wait times for the end-user. Ultimately, these results show improvements the overall end-user experience, and show availability for increased user traffic without increasing existing server & bandwidth infrastructure.

With the changes to WANScaler and Branch Repeater, XenApp users accessing hosted apps over the WAN will be more productive with Citrix ICA WAN acceleration. For example, some of the initial test data showed:

  • Improved application startup time by up to 22-39% per user. 
  • Improved file download capabilities via ICA client drive mapping by transferring data 2-6x faster while using an average of 2-20x less bandwidth.
  • Streamlined ICA print jobs over UPD by reducing bandwidth utilization by 3-30x and thus saving bandwidth for higher priority interactive traffic even while improving the speed of remote print spooling.


Over the coming weeks, we’ll be talking more about the upcoming enhancements to WANScaler and Branch Repeater.  We’ll dive into more details concerning some of the specific assessment testing results, and what they might mean to end-users who already have a Citrix WAN device in place, or are considering the possibility of integrating a device into their existing Citrix infrastructure.

Stay tuned…