Licensing Essentials
Get a grasp on the basics of Presentation Server and Microsoft Windows Terminal Services licensing. (Running time: 23:13 minutes)
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Transcript : Hello, this is Brian Madden. In this video, we are going to review one of everyone’s favorite topics: Citrix Presentation Server 4 Licensing. Before we look at the architecture and configuration of the Presentation Server licensing components, we should take a look at requirements. Now one thing that’s very important to understand, of course, is that Citrix Presentation Server sits on top of Microsoft Terminal Server. So anytime you use Citrix Presentation Server, you also have to have the appropriate Terminal Server licenses from Microsoft. So everything we’re talking about in this video today about Presentation Server licenses is in addition to any licenses that you need from Microsoft for you base terminal server product. So essentially every Presentation Server environment has Microsoft licenses plus Citrix Presentation Server licenses. That being said, one of the factors that sometimes causes a headache for people is the fact that Microsoft Terminal services and Citrix Presentation Server do not use the same licensing model. In the world of Microsoft products—and this applies to all Microsoft products, not just Terminal Server—licenses are for each device or each named user. That means, if you have 100 users in your environment, but only 10 at a time ever use Terminal Server, in the Microsoft world you still have to have 100 client access licenses, one for each user in your environment. That’s very different than the licensing model for Citrix Presentation Server. Citrix Presentation Server licenses are based on concurrent usage. So if you have a million users in your environment, but only five at a time ever use your Citrix Presentation Server environment, then you would only need five Presentation Server connection licenses. In this case, the Citrix licensing is much simpler than the Microsoft licensing. Of course, everyone asks Microsoft when they are going to change to a concurrent model for Terminal Server. But the reality is that’s never going to happen, because all of the rest of Microsoft’s products are also licensed per named user. The only other thing that’s worth mentioning from the requirement standpoint, is that Citrix’s small business product , which is called Citrix Access Essentials, that is for smaller environments with a maximum of one server and 75 users. That Access Essentials product actually includes the Microsoft Terminal Server CALs that you need for your environment. But for all the full-blown Presentation Server products from Citrix, you need to buy your Presentation Server connection licenses on top of your Microsoft Terminal Server client access licenses. Okay, let’s move on and take a look at the architecture of the Presentation Server licensing environment. First and foremost, it’s important to understand that within Presentation Server there is a server that is called a Citrix License Server. Now we’ll look more at the details of that later in this video, but for now understand that there is a Citrix License Server. And what happens is that the individual Presentation Servers within your Citrix Server farm communicates with that Citrix License Server. So the Citrix License Server maintains a list of licenses, and how many licenses you have, and which ones are in use by which users, things like that. And all of the individual Presentation Servers communicate with that one Citrix License Server. One of the things that’s always been very cool about Citrix Presentation Server licenses is, as I said earlier, of course they are based on concurrent connections. However, one user connecting to multiple servers will only use one license. So in the diagram on the screen, we have four Presentation Servers. The yellow arrows show that they are all communicating with a single Citrix License Server. In this particular case, if we had one user who had four separate ICA sessions open on each of those individual four servers, that user would only consume one single license. Which of course is very, very cool. Now, one of the new features of Citrix licensing that was introduced in Presentation Server 3, and of course carries forward to Presentation Server 4, is that fact that, as an administrator, you can manually configure which license server an individual Citrix Presentation Server connects to. And as a matter of fact, this is not limited to farm boundaries. So in this particular case, you see these four Citrix Presentation Servers are sharing one IMA data store. That means they’re on one farm. If we wanted to, we could build a separate Citrix License Server and configure it so that some of the Presentation Servers used the first license server, and some of the Presentation Servers used the second license server. Now, if you do this, one important fact is to remember that one user connecting to multiple servers will only consume a single Presentation Server connection license if those multiple Presentation Servers are talking to the same License Server. So in this particular case, if I have a user who opens a session on server 1, talking to License Server 1, and server 2, talking to License Server 2, that user would consume two connections. Now as far as strategy is concerned with how you build your license servers, we’ll look at this more later on in the video. But the key takeaway right now, is that multiple connections to multiple servers can share licenses, if those Presentation Servers are configured to use the same License Server. Now this diagram here, of course, shows one farm with multiple License Servers. What’s really cool about Presentation Server is that the opposite is also true. What I mean by that, is we can build multiple Presentation Server farms and configure the individual Presentation Servers in those farms to share a single License Server. Now, why would we want to do this? Because if we did, a user connecting to multiple Presentation Servers in multiple farms will still only consume a single Presentation Server connection license. And that is very, very cool. So in the diagram on the screen, we have two server farms, four servers each. If I had a user who’d connected to a couple servers in farm 1, a couple servers in farm 2, because all of those servers are using the same license server, then that means that that user would only consume a single Presentation Server connection license. And what’s nice is this licensing architecture, of course, is not related at all to Microsoft domains, or anything like that. So you can basically point any Presentation Server to any Citrix License Server that you want and share those licenses among users connecting to the Presentation Servers talking to that License Server. Again, very cool stuff. Before we get too much deeper into the Presentation Server licensing conversation, it’s worth mentioning a company called Macrovision. You may have heard of Macrovision in the news recently, when they bought InstallShield. Macrovision is a software company that makes products for licensing and digital rights management and things like that. And Citrix went to Macrovision and licensed Macrovision’s FlexLM product for use in the Presentation Server product. So all of the Citrix licensing architecture that we’re talking about today is based upon Macrovision’s FlexLM product suite. I would imagine that a lot of people watching this video now have existing Macrovision servers in their environments that are providing licenses for other applications. Now one of the things that’s interesting about Citrix’s implementation of Macrovision, is that Citrix environments need to scale very large. And, in fact, one of the requirements that Citrix took to Macrovision was that it must scale to 100,000 concurrent connections. So what this means is that Citrix and Macrovision worked together to customize the Macrovision product so that it works successfully in the Citrix environment. So that means that the version of Macrovision licensing that you get with Presentation Server is not necessarily 100% compatible with the version of Macrovision that you have already deployed in your environment. But the basics are the same. And the architecture is the same. So this might give you a head start in understanding how Citrix Presentation Server licensing works. That being said, let’s take a closer look at the Citrix License Server itself. Now in the diagrams we had earlier in this video, we just showed a Citrix License Server, and we showed the communication between multiple Presentation Servers. Well, the Citrix License Server can actually be pretty much any Windows server. So when you purchase your Presentation Server product, and you have your CD sent, one of the components that you need to install is the Citrix License Server product. But again, that’s a component you can install into a regular file server, or a database server, or a web server, or even onto one of your Presentation Servers itself. The bottom line is it doesn’t really matter where you install that Citrix License Server service, it just has to be somewhere that’s accessible to the Presentation Servers within your environment. Now, if you read the Citrix documentation, they tell you that Microsoft IIS web server is required in order to install the Citrix License Server product. And that’s actually partially true. What happens is Citrix includes a graphical web base license management console that you can use to manage your licensing environment. And this management console is something that we will take a look at later in this video. The key point, though, is this graphical management console is what requires IIS. However, you can also manage the Citrix licensing service from the command prompt and by editing text configuration files. In fact, this license management console is just a gooey frontend for these text configuration files. So in your environment, if you have the requirement to not use IIS, then you still can install the Citrix license service on a server not using IIS. You’ll just have to manage that service from the command prompt. Moving right along, let’s take a look at the architecture of the communication that takes place between the Citrix License Server and the Citrix Presentation Server. Earlier in this video we saw simple yellow arrows connecting both of these servers. So let’s look at what’s actually happening. The first thing that happens is that when a Presentation Server is started, it checks its configuration from the IMA data store and finds out what license server is configured to contact, and it makes an initial handshake connection over TCP port 27000. Now that’s a one-time connection that’s only used for initial establishment of communication. What happens after that is the Citrix License Server dictates a new port that will be used for the connection that is held open for the duration of the servers being online. Now this new port, it’s a random port. The Citrix License Server picks the port. It will use the same port for all of your Presentation Servers, but whenever the Citrix License Server is restarted, that port may change to a different port number. Later in this video we’ll show you how you can hard code that port in case you have a firewall, or anything like that, in between your Presentation Servers and your License Server. The key takeaway here, though, is that the Presentation Server to License Server communication is a two-step process, step one being that initial handshake over one port, step two being the actual connections held open for transmitting licensing information over a second port. What you’ll find is that there will be a decent amount of communication that takes place between these two servers. It’s certainly not a lot in terms of bandwidth. But every time a user connects or disconnects or logs on, you’re going to have that Presentation Server checking with the License Server to make sure enough licenses are available. Of course what that means is that, if the License Server ever disappears, you could be potentially in a lot of trouble. Because a Presentation Server would not be able to validate any licenses. Now Citrix realizes this. And what Citrix has done, is they have built a 720 hour, which works out to 30 day grace period, in the licensing engine that runs on each individual Presentation Server. So if the License Server disappears, the Presentation Server is going to continue to function for 720 hours all by itself, without establishing communication with that License Server. Now when that License Server comes back on line, then the Presentation Server will re-establish communication and life moves on, no problems. The bottom line, though, is that your Presentation Servers can only run for 30 days without a License Server. So if a License Server fails, and it’s not going to come back up anytime soon, you need to make arrangements to create a new License Server. The final architectural component that we should look at before we look at the configuration of your license server is something that Citrix calls License Server Groups. And this also is a new feature of Presentation Server 3, which also carries forward into Citrix Presentation Server Version 4. And, basically, what License Server Groups are, is the way for you to group pools of licenses together that are used for certain Presentation Servers. A perfect example of this is based on the diagram we have on the screen. We’ve got a single Presentation Server environment, five Presentation Servers all using the same Citrix License Server. Three of those servers are serving Office applications, and two of those servers are serving Acrobat applications. In this environment, let’s imagine that we have 300 connection licenses. And that among those 300 licenses, we would like to reserve 200 licenses for Microsoft Office users and 100 licenses for Adobe users. Well the Citrix License Services allows us to configure groups of Presentation Servers, where we could pool 200 Office licenses among those three Office servers, and 100 Adobe licenses across those two Adobe servers. Now this has nothing to do with Presentation Server load balancing. You still need to configure that at the Presentation Server level. All this means is that your 200 licenses shared across your three Office servers can be distributed however they need to be. So maybe it’s about 60 users per server. Maybe you have one server fail, and then you put 100 licenses or 100 users on each of the other servers. Maybe you have 200 users on one server and 0 on the other two servers. The bottom line is that those licenses can be shared in whatever way is appropriate across those two servers. This is much better than the Meta from XP architecture where you could assign specific numbers of licenses to specific servers. You know the problem with Meta from XP was, if I had 4 servers, and I assigned 50 licenses to each of those 4 servers, that meant that if one of those servers failed, I reduced my licensed capacity from 200 users down to 150 users, since there’s only 3 servers left with 50 licenses each. Now, if I have more users I want to run on those servers, I would need to go into my configuration and move licenses around. This Presentation Server 3 and 4 license grouping is much, much smoother than that, since I can just configure the pools of servers and the system automatically makes sure the licenses are available for the specific servers. Now that we’ve talked through the architecture of Presentation Server licensing, let’s take a look at how we actually configure these License Servers. And to do this I’m going to jump onto a live License Server. Now this is the server where I have installed the Citrix licensing service. It’s just a regular file server. It’s not a terminal server or Citrix server or anything special like that. And I’m going to go ahead and launch the Citrix License Management Console. Now, through this License Management Console, here’s where I can actually do some basic configuration things, some basic configuration tasks. As I alluded to earlier, this License Management Console is just a gooey frontend to a text configuration file that the service actually uses on the backend. So if I go here into Program Files and then go to Citrix, I will see a folder here called Licensing. And, again, it’s okay if you install this licensing server on a Presentation Server. You’ll see several folders underneath the Citrix folder. But in my case it’s a standalone server, so I see a Licensing folder. If I go into this MyFiles folder, I see a folder here called CITRIX.opt. That stands for Citrix dot options. If I open this options file, I see a few different configuration options that have been listed here. And certainly there’s dozens of more settings and changes you can make. So, things we talked about earlier, those License Server Groups, for example, and configuring these kinds of things, these are all things that you can configure by editing that Citrix dot options file. It’s actually interesting to note, you will not see anything in here about Citrix License Server Groups. All of that kind of stuff you can only edit by accessing the CITRIX.opt file. By the way, if you like to see what can be done with this Citrix configuration file, then you can go to Citrix’s web site, and you can download the documentation that is packaged along with Presentation Server 4. And we’ll grab that here. And you should find on this list the suite licensing guide. Here it is. And if you read this PDF document, there is a very detailed listing of all the options you can configure in that opt file, including the License Server Groups and hard coding the ports, as we discussed earlier, and all sorts of things like that. So this is a great document to have. It looks like it’s 106282 for that document. But anyway, going back to the configuration of our License Server, the other important concept we have is the concept of license files. And what you may remember, is that in older versions of MetaFrame, you received a product code from Citrix, which you entered into the MetaFrame administrative console, and that allowed you to add licenses. Well, in the new way that Citrix functions, everything is done via MyCitrix. So I log into my MyCitrix account. You’ll see I have an option here for licensing, which is where I can add license keys and download my license files, and things like that. So I download these license files, and I copy them into the MyFiles folder under the Licensing Server on my Citrix License Server. Now, what’s interesting is when you download a file from Citrix, it has a name license and then underscore with a time stamp associated with when you downloaded that file. I find, personally, that it’s easier to rename that file so that it has some kind of meaningful name. So, perhaps this is Presentation Server 1000 concurrent users expiring in June 2007. So I’ll rename those files so that they’re meaningful to me. The Citrix License Server doesn’t care what the files are called. As long as they have the .lic extension and they are in the MyFiles folder, then they’re going to be okay. Let’s actually open up one of these files and take a quick look at it. To do so, I’m going to right click and do Open With, and choose to open with WordPad, not with Notepad. The reason is, these are UTF-8 encoded, and so Notepad doesn’t really handle all the special characters properly. Well, what you’ll see here, everything that starts with a hash sign is just a comment. But you’ll see I have in here all sorts of things, like, here’s my grace period, the version that I am was Enterprise Advanced and Standard. We have all sorts of things, expiration dates, numbers of users. This is a 1000 user license, for example. So we’ll see all sorts of data that is here in this license file. Of course, people look at this file and say, “Oh, wow, it’s 1000 users. Well why can’t I just take my 5 user license file and change the text right there and turn it into a 1000 user file?” And the answer is because of this sign option you see right here, this SIGN key with all these hex codes after it. This is sort of an encrypted hash that signs everything that precedes it here. So what that means is, if you change anything up in this area right here, that won’t match that encrypted signature that’s down here, and the license file will be invalid. So you don’t want to change anything in the license file, unless it’s something that you can specifically change. A couple other interesting things to mention about Citrix licensing. Number one, you’ll notice the host name here. In my case, it’s called bmlab-dc1. What’s important is that when you download your license file from MyCitrix, it’s going to ask you the host name of the server that you intend on using that license file with. And you need to type that server name into the web site, and when it builds that license file for you, it has embedded into it, as you can see right here, the host name. And this is the host name; you cannot change this later. If you change this host name later on in your license file, that will invalidate this signature down here, and the license file will not work. So you need to think about what server you’re putting your license file on. And if you end up moving it or having to move it, you need to go back to MyCitrix.com and turn in your old license file and have them generate a new license file for you. The second very important key to mention about license files, is that Citrix license files are not tied to specific versions of Presentation Server. Instead, they are tied to dates. Now what this means is there is no difference between a Presentation Server 3 and a Presentation Server 4 license. All that happens is these license files are for Presentation Server and a specific edition--like Standard, Advanced, or Enterprise—and a certain number of users. So, for example, you may have a license file that is for Presentation Server Enterprise edition 1000 concurrent users. And that license file will have a date embedded into it, and that is a date of when your subscription advantage expires. So what happens is that all license files can be used with any version of the Citrix Presentation Server product, as long as long as that product was released before the expiration date of your subscription advantage. The way Citrix handles this is that every single Citrix product has what they call a burn-in date. And so, for example, the burn-in date for Presentation Server 4 might be April 27, 2005. So any Citrix Presentation Server license file you have that shows your subscription advantage expired after that date is going to be valid for that specific version of Presentation Server. So what this means is, that as Citrix releases new versions of Presentation Server, you do not need to download new license files, because your existing license files will be fine as long as your subscription advantage is up-to-date. This does mean, though, if you renew your subscription advantage, you will need to go to Citrix’s web site to download new license files, because you’ll need to download new license files that have the new expiration date of your subscription advantage. With that, you now are up to speed on the basics of Citrix Presentation Server licensing. I’d like to thank you for listening today. I would like to thank my colleague, Katie Kepkie, for building all the slides and animations for us. And I’d like to wish you all happy licensing. Thank you.
anonymous - Well done, Very interesting topic with fragile information on citrix licensing and presentation server.<br>
erimushousing - Brian talks like a fool
erimushousing - like a cyborg