Citrix Query - Citrix Performance

Our latency from India to US is 260ms to 280ms, Whenever it crosses 300ms ++++ users started facing slowness in accessing the citrix applications.

- When we checked the bandwidth its less than 50% utilization from total bandwidth
- Found few users who downloads the files\data through internet or downloading large mails, To fix the problem we requested users to stop the downloads.

Management requested us to fix the problem without requesting the users to stop the downloading and logoff, as the utilization of total bandwidth is less than 50% why citrix session is slow when it cross 300ms.

- Is there any limitation in citrix which works fine in 260ms to 280ms?
- If we go for a ica compression (Cisco WAAS or Citrix Branch Repeater) will fix the issue? If so which one is the best tool to procure.
- Is the any default compression available in citrix without using any compression devices?

Environment
- Presentation Server 4.5
- Xenapp 6.5
LVL 26
Sekar ChinnakannuStaff EngineerAsked:
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dipopoCommented:
I'd look at Speed Screen Latency reduction for mitigating your latency issues.

http://www.brianmadden.com/blogs/brianmadden/archive/2004/09/06/understanding-citrix-s-speedscreen-latency-reduction.aspx
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BlueComputeCommented:
From that article (which by the way is from 2004)
SpeedScreen is automatically used on a MetaFrame server whenever a user connects to a session that has between 150 and 500ms of latency. As long as the client supports it, it's used.

I believe that the Citrix Branch Repeater would improve the user experience here.
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Sekar ChinnakannuStaff EngineerAuthor Commented:
can you answer these queries

- Is there any limitation in citrix which works fine in 260ms to 280ms?
- If we go for a ica compression (Cisco WAAS or Citrix Branch Repeater) will fix the issue? If so which one is the best tool to procure.
- Is the any default compression available in citrix without using any compression devices?
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Casey HermanCitrix EngineerCommented:
In the web interface you can dial down the session display settings from 32bit to 16bit. Set the audio rate to low.   These alone will give performance improvements.  When it comes to traffic you need to also look at the client connections. If you are only utilizing 50% on your bandwidth it means that the client it probably slow to talk back to your datacenter. Speed screen can help here as well as mentioned by others.  

We had a similar issue here and the solution I came up with was to add secondary set of application servers at the large office. We published a desktop so Pointed all of their thin clients to a published desktop on the remote site. Then the only thing that talked across the network was servers to the zone data collector and DFS that replicates the files via sites and services. It has been working really well. We should have probably set up a branch repeater.

-Casey
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BlueComputeCommented:
Hi sekarc4u,  to answer your questions:
1) Specific limitation around 260-280ms?  No
2) A WAN acceleration device will almost certainly improve the user experience, not so much by compression but through caching and de-duplication.  I'd expect the Citrix product top work better with XenApp than the Cisco WAAS.  I don't think that's what WAAS is mainly intended for.
3) By default Citrix XenApp uses its own ica/HDX compression, ie. it is already using compression, so further compression is unlikely to offer much benefit.
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Sekar ChinnakannuStaff EngineerAuthor Commented:
ok How can we calculate ICA compression as per http://community.citrix.com/display/edgesight/ICA+Session+Compression
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BlueComputeCommented:
Apparently you can do it using Edgesight, according to your link.  The real question is why you would do that?  You already know that your latency is giving you grief over 300ms.  Compressing the heck out of the ica stream (or not) isn't going to make the slightest difference to that, is it?
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Sekar ChinnakannuStaff EngineerAuthor Commented:
It's slow when we cross 300ms
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BlueComputeCommented:
Right, you said that.  And that's a latency issue, not a bandwidth issue, so I'm confused as to why you're still asking questions about compression?
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Casey HermanCitrix EngineerCommented:
This is where speed screen comes in.
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joharderCommented:
First, I would never recommend using SpeedScreen Latency Reduction.  Not only is it painful to set up, users typically hate it because the fonts change on the screen.  It's a very old technology, and there are much better options available.

Your WAN connection is somewhat latent, and there isn't a lot of breathing room before you get to 300 ms and your users start to feel some pain.  So, yes, something like Branch Repeater would likely help you.

One of the key differences between Branch Repeater and Cisco WAAS is that Branch Repeater lets you get more granular with ICA prioritization.  With XenApp 6.5, for example, you can use multi-streaming, which lets you reclassify the ICA prioritization groups into TCP ports, and then you can prioritize that way.  Bottom line either way is that Branch Repeater will likely help you, and I'd recommend trying that solution first.

Although EdgeSight is great for seeing the compression of connections, you can't do much about it unless you add something like Branch Repeater.  I must say that I do love EdgeSight for it's ICA related info, but you must have Platinum in order to see that data.

So far as the users downloading/transferring large files, you should limit those transfers via either your router or Branch Repeater.  Although you have asked the users not to do this, you should force a cap to be sure.

One of the most overlooked bandwidth hogs is ClearType.  It can use 2x bandwidth.  It is automatically enabled on Win7 devices and disabled on WinXP devices.  Users like ClearType, but if you don't have the bandwidth to support it, disable it.

Of course, you can also set some limitations on bandwidth for printing and other functionality within Citrix policies.
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