Secondary Connection Brokers
A secondary Connection Broker is added to a Site for redundancy. This way if the primary Connection Broker fails, the secondary Connection Broker is still available to handle the requests. Connection Brokers work in active/active manner to ensure high availability. In case of a Connection Broker failure, the next agent is always ready to handle the load. In general, the N+1 redundancy approach should be used per Site. Note that for auto-promotion you shouldn't have more than three Connection Brokers (auto-promotion is described later in this section).
When you have one more secondary Connection Brokers installed, the runtime data is replicated on each agent, so if any service fails, the downtime is reduced to a minimum. In addition, any active Connection Broker is used for authentication purposes with both the AD and any 2nd level authentication provider used.
The primary Connection Broker performs the same tasks as secondary Connection Brokers but has additional responsibilities. It manages certain processes that must be managed by a single Connection Broker. The following table lists processes managed by the primary Connection Broker and secondary Connection Brokers:
Monitor PAs (counters)
Yes
Yes
Monitor RD Session Hosts (counters)
Yes
Yes
Monitor Providers (counters)
Yes
Yes
Monitor RDS Sessions (reconnection)
Yes
Yes
Monitor Deployed RDS applications
Yes
Yes
Monitor VDI session (reconnections)
Yes
Yes
Manage system settings
Yes
No
Send licensing information & heart beat
Yes
No
Process and send CEP information
Yes
No
Send information to reporting server
Yes
No
Manage RDS scheduler
Yes
No
Reporting engine information
Yes
Future versions
Shadowing
Yes
Future versions
Send email notifications
Yes
No
As a demonstration of how load distribution between multiple Connection Brokers works, consider the following example:
Suppose we have two Connection Brokers: PA1 (primary) and PA2 (secondary).
Suppose we also have 10 RD Session Hosts: RDS1, RDS2 ... RDS10
The resulting load will be distributed as follows:
RDS1, RDS2 ... RDS4 will use PA1 as their preferred Connection Broker.
RDS5, RDS6 ... RDS10 will use PA2 as their preferred Connection Broker.
Planning for secondary Connection Brokers
RAS Connection Brokers running on the same Site communicate with each other and share the load. The amount of data being transmitted from one agent to another is quite large, so a reliable high-speed communication channel must be ensured (e.g. a subnetwork can be configured for Connection Broker communications).
When adding a secondary Connection Broker to a Site, you specify an IP address for it. Make sure that the IP addresses of all agents belong to the same network segment. The port that Connection Brokers use to communicate with each other is TCP 20030.
There's no physical limit to how many Connection Brokers you can add to a Site. However, the best results are achieved with only two-three agents present. The three-agent scenario is highly recommended, especially when you have Providers and want to enable high availability for VDI. Adding more than two secondary Connection Brokers to a Site may have a reverse effect and actually degrade the system performance. Note that this does not apply to secondary Connection Brokers in standby mode, which is explained in Configuring RAS Connection Brokers.
Adding a secondary RAS Connection Broker to a Site
To add a secondary Connection Broker:
In the RAS console, navigate to Farm > <Site> > Connection Brokers.
Click the Tasks drop-down list and choose Add to launch the Add RAS Connection Broker wizard.
The Server field specifies the FDQN or IP address of the server that hosts the RAS Connection Broker. To automatically resolve IP address to FQDN, enable the global Name Resolution option. For details, see Host Name Resolution.
The IP field specifies the server IP address. Click the Resolve button to obtain the IP address automatically using the FQDN specified in the Server field.
The Alternative IPs field specifies one or more alternative IP addresses, separated by a semicolon. These addresses will be used if RAS Secure Gateways fail to connect to the RAS Connection Broker using its FQDN or the address specified in the IP field. This can happen, for example, if Secure Gateways are connecting from a different network, which is not joined to Active Directory.
Select the Install a Secure Gateway with a Connection Broker option if you also want to install a RAS Secure Gateway on the specified server. If you select this option, you may also select the Enable HTML5 Gateway option (for more info, see Configure User Portal).
Select the Add Firewall Rules option to automatically configure the firewall on the server. See Port Reference for details.
Click Next.
On the next page, click Install to install the RAS Connection Broker on the server. The Installing RAS Redundancy Service dialog opens.
Select the server on which the RAS Connection Broker is to be installed and click Install.
Click Done.
Click OK to add the server to the Farm.