We sometimes get questions regarding the scalability of the RSA SecurID Access Cloud Authentication Service. Customers who are used to managing on-premises solutions want to know how many machines they need to set up to support their end user population during peak periods. But since the Cloud Authentication Service is a hybrid solution, the scaling considerations are a bit different.
If you use the Cloud Authentication Service to provide primary and/or additional authentication to relying parties, scalability is simple because the cloud components are designed to scale to meet your needs. The hybrid architecture still involves an on-premises identity router, which provides a secure connection to your identity source(s), but its role is minimal at runtime. Just make sure you deploy more than one identity router for redundancy, in case one goes down.
If you use the identity router for RADIUS-based access control, all you need to do is make sure you have redundant identity routers with RADIUS enabled. The Cloud Authentication Service handles the heavy lifting.
If you want information about scalability and you use the SSO Agent capabilities, you can read more about that in the RSA SecurID Access SSO Agent Performance and Scalability Guide.