* The ins and outs of Citrix
We’ve written quite a bit about the challenges of supporting remote users. One piece of the remote picture we shouldn’t neglect is the Citrix Systems thin-client Independent Computing Architecture. Citrix remains in use, often alongside Web-enabled applications, in many enterprises.
Citrix ICA evolved to provide LAN-like connectivity to WAN-connected users. Users run a Citrix thin client and basically work in terminal application mode running so-called Citrix Published Applications. These can be any applications published to special Citrix MetaFrame Presentation Servers in corporate data centers.
Citrix servers proxy the usually chatty applications developed for LANs. The servers and thin-client software exchange only user inputs, mouse movements, and GUI updates over the WAN. Because of this streamlining and use of Citrix compression technology, each Citrix Published Application, including print jobs, consumes a stream of just 10K to 25K bit/sec of WAN bandwidth, according to Russ Naples, Citrix vice president of product development.
This is what keeps user response times LAN-like and, for some users, trumps the bursty Web experience.
The architecture supports five client operating systems and returns a screen formatted appropriately to the device in use, be it a Windows CE handheld or a Mac OS-based laptop. The compression has tunings that help wireless devices minimize latency, Naples says.
Citrix is reportedly looking into accommodating converged voice and data applications, as well. “That’s clearly an important piece of improved access our customers will expect us to deliver,” Naples says.
The overarching Citrix MetaFrame Access Suite supports security policies that identify users, determine what device and connection type they are using and grant permissions based on these variables. For mobile/wireless users, the system can also provide access to a printer local to wherever they are.
Meanwhile, if you are using Layer-7 traffic management and running multiple Citrix Published Applications, you can assign a unique performance-management policy to each Citrix application.
You’ll likely want to ensure each session per Published Application gets its required 10K to 25K bit/sec. Otherwise, if you assign an aggregate amount of bandwidth to each app, more and more concurrent sessions might be opened, but none might have sufficient bandwidth to perform adequately.
CORRECTION: In our Nov. 9 newsletter, “Service bundles gain cellular access options,” 1xRTT service usage should have been estimated at speeds of about 144K bit/sec, not 144M bit/sec. We regret the typographical error.
