> For the complete documentation index, see [llms.txt](https://docs.parallels.com/landing/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.parallels.com/landing/ras-reference-architecture/v19/deployment-scenarios/parallels-ras-deployment-scenarios/high-availability-with-multiple-gateways.md).
# High Availability with Multiple Gateways
This scenario is ideal for high availability environments with more than 300 concurrent users connected in SSL mode. Each client gateway should optimally handle 300 to 500 concurrent user connections\* (see the note below). This can be scaled horizontally accordingly.
Both LAN and WAN users connect to IP address of the HALB VS which represents the HALB virtual appliances in the internal network.
Please note that the diagram above includes an optional secondary RADIUS server which can be used as active/active or active/passive to provide high availability.
See also [**Capacity Considerations**](/landing/ras-reference-architecture/v19/capacity-considerations.md).
All RAS Secure Gateways must be configured to connect to the same RAS Connection Brokers (using the Advanced Client Gateway Settings—see above).
**Installation Notes**
RAS Connection Broker is installed using the Parallels RAS installer (standard installation).
HALB is installed as a ready-to-use virtual appliance and configured in HALB VS properties.
All other components are push-installed from the RAS console.
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