The tutorial will go through the steps of installing an additional RD Session Host Server, and how to deploy it as part of a Farm that hosts an application collection. It will show how to connect via Remote Desktop into the RD Session Host Farm from the internal network.
Accessing the RD Session Host Farm from an external network (e.g. internet) can be done through the use of the Remote Desktop Gateway. This will be discussed in another tutorial.
This tutorial requires that Remote Desktop Services for Windows 2016 be already installed. It will show how to add an additional RD Session Host server to the RD Session Host Farm.
Summary of Steps
The following is the list of steps required to set up load balancing between the RD Session Host servers.
- Plan the installation
- Setup Remote Desktop Services
- Install Remote Desktop Session Host Server on a 2nd Server
- Add the 2nd RD Session Host server to the Collection
- Configure Load Balancing
- Add DNS Entries for the RD Connection Broker Farm
- Testing Remote Desktop Connection Broker on the Internal Network
Plan the Installation and Setup Remote Desktop Services
You will need to plan what servers will have the necessary roles to be installed.
We need servers for the following roles:
- Remote Desktop Web Access
- Remote Desktop Gateway
- Remote Desktop Connection Broker
- Remote Desktop Session Host (1st Server)
- Remote Desktop Session Host (2nd Server)
Follow this related article to plan and install Remote Desktop Services in Windows 2016.
We will use the same server naming convention used in the related article and place the same corresponding roles on the servers.
Install the first Remote Desktop Session Host role on the RDSERVICES server.
Follow the below information to install the Remote Desktop Session Host role on the second server. The second server will be called RDSERVICES2.
Install the Remote Desktop Session Host Server Role on the 2nd Server
Install a Windows 2016 Server called RDSERVICES2 and join it to the domain.
Connect via Remote Desktop to the RDSERVICES server. This was the server we had used to configure Remote Desktop Services from the steps above.
On the RDSERVICES Server, launch Server Manager, and we will add RDSERVICES2 to be managed.
On the left hand pane of Server Manager, click on Remote Desktop Services.
Configure a Collection Across Multiple RD Session Host Servers
We will now configure the Applications1 collection (created in the related article on How to Setup Remote Desktop Services in Windows 2016) to also be hosted on RDSERVICES2.
Click on the Applications1 collection.
Scroll down to the Host Servers section. Currently only RDSERVICES is hosting the collection. We will now add RDSERVICE2 to also host the collection.
Select the Add RD Session Host Servers option from the Tasks menu.
Configure Load Balancing
We will now configure the load balancing settings for the Applications1 collection.
Scroll up to the Applications1 properties section.
Select Edit Properties from the Tasks menu.
Open up the load balancing section.
The current setting is Relative Weight 100 for both the RD Session Host servers. What this means is both servers will share the users remote desktop sessions 50-50.
You can increase (or decrease) the relative weight to control which servers will end up having more sessions.
If you want to drain a particular server of users if you are going to be doing maintenance on the server, use a value of 1 for the relative weight of that server, and keep your administrator account logged into that server. This means any new connections will be redirected to the second server. Existing connections will not be affected. As users log off, the server will be drained of user sessions so you can begin doing your maintenance.
Note: You cannot use a value of 0.
Bypassing Connection Broker
If you try to Remote Desktop to a server that's load balanced and you are using the server's name, you may get an error message. The reason is that the connection broker may try to redirect your session to a different server than the server that you initially tried to connect to. When this happens, you will get the following message:
However, there are times when you really do need to connect to a specific server in the farm. In this case, you will need to start up the Remote Desktop client with the "/a" switch. This can be typed in the command line or the run box.
e.g. mstsc /a
This will launch the Remote Desktop client in administration mode, and its session will not get redirected.
Add DNS Entries for the RD Connection Broker Farm
Following on from the above, where you will sometimes get an error message if you try to Remote Desktop into load-balanced servers using one of the server's name, you will need to create DNS entries for the RD Farm. The DNS server should be enabled for round robin DNS. The RD Farm name can be anything you like, as long as it's accepted by the DNS server e.g. RDFarm. The reason why we need the DNS server to be enabled for round robin DNS is that we will have multiple entries for the RD Farm name, with each entry pointing to each server's IP address that is in the farm.
Navigate to the DNS zone, and create the DNS entries for the farm.
DNS Round Robin Load-Balancing and Connection Broker
By using the farm DNS name for the server name in the Remote Desktop client, we are using DNS round robin to decide which RD session host server is going to have the initial connection. This is called DNS round robin load balancing.
Once the user has authenticated to the RD session host server in the farm, the server then contacts the connection broker to determine whether to continue with the login process or to redirect the connection to another RD session host server in the farm.
The connection broker firstly determines whether the authenticated user account has a disconnected session on one of the servers in the farm. If there is a disconnected session on one of the farm servers, the user will be re-directed to that session. If the user doesn't have a disconnected session in the farm, the broker uses the Session Collection Load Balancing settings to determine which server to redirect to.
An exception to the Session Collection Load Balancing settings, as mentioned previously, is if the remote desktop client was started from the command line or the run box with the "/a" option e.g. mstsc /a .
Testing Remote Desktop Connection Broker on the Internal Network
To connect to the farm, use the DNS name of the farm for the computer name in the Remote Desktop client.
To test if the connection broker is doing its job, we can adjust the relative weight of the server that we have just connected to in the farm to 1.
In the above example, we have connected to the RDServices server. We will adjust the relative weight for it to 1. We can then remote desktop into the farm using a second user account and we should see it connect to the second server.
If you have a disconnected user session or even a non-disconnected user session on a server in the farm, the connection broker will redirect your connection to this session if you try to log in as that same account.
To test this, we can remote desktop to the farm as the account that’s currently logged into the RDServices server. Despite the relative weight being 1, the connection broker will redirect the user to the RDServices server.
We have now completed creating a Remote Desktop Session Host Farm, serving an Application Collection, and managed by the Remote Desktop Connection Broker.
We can connect to the RD Farm on the internal network.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: What happens, when the rd-sessionhost is offline? Then he couldn't contact ste SB and therefore, alls initialconnections (RR) will not get connected.
Answer: Yes, what happens when the rd-sessionhost is offline, and it's part of the DNS load balancing? I haven't confirmed via WireShark or other networking tools, but I have done this test, and have one server which is part of DNS load balancing turned off. The RDP Client looks to do a retry and the only noticeable sign to the user is it takes a little longer before it eventually logs in. A Microsoft engineer can probably confirm how it works, but on the surface, it looks like it's engineered to retry by re-connecting to the Computer name again. Then eventually it will resolve to the IP address of an online server.
Question: Did you know, I found that for the DNS alias to work you have to edit your Resource Allocation Policy to "allow all network resources"? Otherwise, very help guide.
Answer: If you click "allow all network resources", it will allow those users in the group to access every server and PC in the network. Perhaps you haven't assigned a group of computers to be accessed in that policy? Also, I found on one network, when I assigned an AD group of computers, I had to use the computer name and not its FQDN i.e. COMPUTERNAME instead of COMPUTERNAME.domain.local, to connect to it.
Question: When trying to connect to a specific Remote Session Host by using the /admin parameter, a domain user (not admin) gets the message "requested access to the session was denied". Is there any way to connect to a specific host for standard users?
Answer: Not that I am aware of. The /admin mean does mean for users with administrator privileges.
Question: I have a question regarding taking a server offline using the "do not allow connections." How do you ensure the user does not connect to the offline server with DNS round robin enabled?
Answer: When a user remote desktops to an RD server that is part of an RD Connection Broker farm, the RD server firstly checks with the RD Connection Broker server whether it's allowed to continue the user login process on that RD Server or gets redirected to another server. If the server that the user first hits have the "do not allow connections" settings, it will be redirected to another server in the farm. The only exception is that if the user already has a disconnected or active session on an RD Server in the farm, then the Connection Broker will redirect it back to that server with the existing user connection, even if it has the "do not allow connections" settings.
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