Citrix over MPLS

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Jan 25th, 2008
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Our company is going to implement a Citrix Farm at the data-center. There will be 6 presenation servers with two access gateways. There will be 60 concurrent users at a remote site. These Citrix users will be accessing via an MPLS WAN. The data-center MPLS connection is load-balanced with two DS3s (45mb). The remote site is load-balanaced with two sub-rate DS3s (9mb).

I want the best user/client performance as possible. The user (Citrix) client will use a web application. There will no printing or drive mapping etc. I have experience with end-to-end QoS. But I wasn't sure whether to investigate WAAS or other types of WAN optimization.

I was going to apply a QoS policy on the network for Citrix data. Should I look at WAN optimization as well? Has anyone had any experience with latency or problems? Could someone recommend a best practice or link?

Thanks a lot , always appreciated.


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Overall Rating: 5 (2 ratings)
paolo bevilacqua Sat, 01/26/2008 - 03:29
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I know that this may not be the reply consider it comes you expect, but consider it comes in full honesty from almost 20 yrs experience in networking.

Do not design QoS on paper, implement the network in the simplest manner first, and monitor it for a while.

Check that traffic volumes and patterns are the ones that you have dimensioned the circuits for.

Check that you can make huge copies across, do voip, whatever else without disturbing the core business.

Check that there are no errors anywhere, redundancy is working as expected, and most important, everyone is happy.

Also secure it as necessary.

Measure, with netflow, span port or whatever you like, traffic volumes per application, that will be your baseline for eventual QoS configuration.

In a word, sanitize your network 100%.

After you have done all that, chances are, you will need QoS as a safety precaution, and you have all the elements to make an intelligent guess of how much and where you need it.

Joseph W. Doherty Sat, 01/26/2008 - 06:02
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My experience has been, if your Citrix traffic shares the media with other traffic, enough so that any congestion forms, QoS is a must to insure the best possible performance.

Assuming you're MPLS topology is some kind of mesh, besides your interfaces feeding into MPLS, critical congestion points can form at the MPLS egress points (feeding to you). For instance, your DC has a 45 Mbps feed that only has a 9 Mbps egress. You need to know what the MPLS provider's QoS model is and use it (usually by marking traffic) to insure the Citrix traffic has sufficient bandwidth that it rarely, if ever, queues. (If you don't have a mesh, just a logical point-to-point, you can shape and use QoS before you feed into MPLS.)

You note that you won't have Citrix printing or drive mapping traffic. If you do in the future, the latest Citrix NBAR version can look into the Citrix packet and tell the difference. I.e. you can treat the different kinds of Citrix traffic differently.

As to the various WAN optimization products, they often deliver amazing performance for most types of larger, non-encrypted or not compressed, data transfers. They're usually not nearly as effective with highly interactive small volume data transfers. One caution, their deployment can push a WAN link much harder, in a short duration, actually increasing the need for QoS. (Also note, as Vista and its corresponding servers become widely deployed, they too push data much harder in short durations.)

Other things to consider: you might want to look at Corvil bandwidth analysis, if your IOS supports it, to confirm you have provisioned enough bandwidth. You might also consider using OER/PfR (12.3T or later) to insure your critical traffic runs across the best performing path.

msrohman Sat, 01/26/2008 - 10:36
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Wow. Both of these replies are really helpful, thanks a lot. I'm going to study these responses and include changes into my project plan.

I'm never let down in the amount of knowledge and experience in these forums.



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