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We are currently reviewing the bandwidth of our WAN links. How much bandwidth does a "typical" Citrix session utilize over a WAN link? JFYI - we are using Citrix Program Neighborhood V10 and each session is configured to use 256 colors.

I have set up PRTG and it appears that for a server hosting 4 users, the traffic is approximately 100k to 300k per session. Is that about right?

If you had to set a benchmark on a per-user basis, how much bandwidth would you assign to each user?

Thanks in advance.

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4 Answers 4

That seems too high. I would have expected about 100k max and more like 60k. Are you able to log in to one of the Citrix sessions yourself? If so the client can show you stats on bandwidth. Similarly at the server end you can see this, for example in Windows counters and possibly in the zone data collector (that's from foggy memory though).

What kind of applications and window resolutions are in use, and how many at once? Or is it published desktop sessions? Are there additional local peripherals or other custom session traffic?

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In our typical setup, we have a farm with 3 servers hosting a single published application. Whenever we set it up for the user, we use the Basic encryption, 256 Colors and Window Size is 640x480. No sounds are enabled but printers are mapped. Apps are finance related and data refreshes are very frequent. –  molecule Mar 12 '10 at 7:44
    
@molecule: Just so you know, no actual application data ever passes through the ICA (or RDP) session. The only "data" that passes through the session is print data, drive mapping data, sound data (if sound is being redirected), mouse clicks, key strokes, and screen draws\refreshes, in a nutshell. –  joeqwerty Mar 12 '10 at 12:43
    
@joe: thanks for the clarification :) –  molecule Mar 15 '10 at 1:04

100-300k seems a little high using that color level. Are you just noting the total amount of bandwidth used by the server and dividing by four? You might want to account for other traffic from the box. Edit: I'm assuming you're monitoring the switch port or the server NIC with PRTG? Do this: Monitor the traffic with no users. Write that number down. Add one user. Write that number down. Repeat. Find out what the increments are. This number will be inaccurate (in fact, very misleading) if the users' applications within the session generate LAN traffic : for example, if they're running a SQL client that connects to a local SQL server, or a local file share, that's not internet-bound traffic

You could measure the bandwidth used by ICA (TCP 1494) at the gateway if your router supports that kind of monitoring. That gives you an immediate and correct answer for total bandwidth.

What problem are you trying to solve? If you need to minimize bandwidth, Citrix has a lot of options for defining policies, as well as optimizing different parts of the ICA protocol. What version of Citrix are you running? If you're running a recent version at the highest-level edition, it has SNMP support for monitoring, the answer may be right in there and you could monitor that with PRTG.

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Hi, Thanks for your reply. Yes, since I do not have any other method of estimating bandwidth, I am currently just noting the total amount of bandwidth and dividing by four. Completely agree that other traffic need to be accounted for as well. How much would you allocate for each session? –  molecule Mar 12 '10 at 2:13
    
Yes, I currently have PRTG monitoring the switchport that the server NIC is connected to. I understand it is a bit difficult to capture the exact number (given my limited knowledge and tools) but was looking more for a ballpark figure. I am also not completely familiar with Citrix. As indicated, Program Neighborhood is v10 and MetaFrame Presentation Server is v4.0. As for my "problem" - we have a 6Mb point to point link which we are planning to downgrade as it appears to be under-utilized and I was going through this exercise just to make sure that I have accounted for Citrix traffic. –  molecule Mar 12 '10 at 3:41
    
Well OK then, you should definitely read up on ica and citrix, and what you can do with them (and what they do out the box) –  mfinni Mar 12 '10 at 4:31
    
@mfinni: Can't get an accurate measurement? Why not? It's not difficult to install PRTG on the server, set up a packet sniffing sensor, and filter your capture for just ICA traffic. Connect one user, capture traffic, filter for ICA, and bada-bing, bada-boom, you have your ICA bandwidth mesaurement per user. What's so hard? –  joeqwerty Mar 12 '10 at 4:46
    
@mfinni: Note that I didn't downvote your answer, even though your suggested monitoring method is prone to producing innaccurate, misleading results. If the OP wants to know exactly how much bandwidth is consumed by a Citrix session then the best way is detailed in my previous comment. –  joeqwerty Mar 12 '10 at 4:51

XenApp should NEVER use 100-300kbps for general usage. Printing would increase outbound usage from your servers and scanning with a scanner or using other USB peripherals with input other than typical XenApp activity would be the only way you should even come close to 100kbps.

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100K to 300K sounds about right to me, although for that color depth it might be a little high. We've measured our bandwidth usage at roughly the same levels, although we have our color depth set to 16 bit. The way we measured it was to have one of our support engineers run a PRTG packet sniffer sensor, filtered to capture only RDP traffic for 8 hours and then averged the results over those 8 hours. The average turned out at about 200Kbps. The big bandwidth hogs (and session killers) are PDF documents and web browsing (because of all the dynamic content on most web pages these days).

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If that's for rdp, not ica, then you're not making a valid comparison for what the question is asking. –  mfinni Mar 12 '10 at 4:29
    
@mfinni: C'mon. My answer gives the OP some info to go on and also suggests a valid method for measurement. Yes, ICA is "supposedly" less bandwidth intensive than RDP, but my answer gives the OP good info. While my answer doesn't specifically address ICA, it's hardly worth a downvote. Me thinks you're too liberal with the down button. Ease up, mate. –  joeqwerty Mar 12 '10 at 4:39
    
it's not "supposedly", at all - out of the box to begin with, and there's a lot of optimization and/or throttling you can do. You can optimize ICA to the point that it uses about 10-20k per session. It was created when common connection methods used phone lines - you used to be able to dial-in, not even over PPP, to a Citrix server, and could host 3-5 sessions per phone line at 56k. –  mfinni Mar 12 '10 at 5:12
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@mfinni: I've read the hype many, many times about how great ICA is and how much better it performs vs. RDP, but I've yet to see definitive, unbiased evidence to that effect. If you could point me to such evidence, I'd appreciate it as I'd like to finally put the question to rest for myself. Thanks. –  joeqwerty Mar 12 '10 at 12:08

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