In today’s business-critical landscapes, high availability (HA) is not just a luxury—it’s a necessity. Enterprises running SAP systems require seamless, secure, and resilient access to their applications. SAP Single Sign-On (SSO) enhances user experience and security by allowing users to log in once and access multiple SAP systems without re-entering credentials. When deployed in high-availability environments, SAP SSO must be architected to support fault tolerance, failover, and redundancy to ensure uninterrupted authentication services.
This article explores how to implement SAP SSO in high-availability scenarios, the architectural considerations involved, and best practices for ensuring secure and resilient identity management.
SAP SSO integrates several components that need to be considered for HA deployment:
Secure Login Server (SLS)
The Secure Login Server is responsible for issuing short-lived X.509 certificates used in authentication. It plays a crucial role in certificate-based SSO mechanisms.
Secure Login Client (SLC)
Installed on end-user machines, this client manages the authentication tokens and certificates provided by the SLS.
Kerberos Authentication
When integrated with Microsoft Active Directory, SAP SSO can leverage Kerberos for seamless authentication in Windows-based environments.
SAP Web Dispatcher / Load Balancer
Used to route authentication requests to the appropriate SAP backend systems.
LDAP/AD Integration
Essential for user identity validation and retrieval of credentials or certificates.
To achieve HA for SAP SSO, you need to consider both application-layer redundancy and infrastructure-level fault tolerance.
Clustered Deployment:
Deploy multiple SLS nodes in an active-active or active-passive configuration. Use a network load balancer or DNS-based load balancing to distribute client requests.
Session Replication:
Ensure that session data is replicated or shared across SLS nodes (using a shared database or session management strategy) to prevent session loss during failover.
Failover Handling:
Clients should be configured with fallback URLs or be able to retry authentication against alternate SLS nodes.
Use clustered or replicated databases (e.g., SAP HANA System Replication, Oracle RAC) for storing configuration data and certificates issued by the Secure Login Server.
The database should be reachable from all SLS nodes with consistent latency.
Integrate SAP SSO with highly available LDAP or Active Directory services.
Use multiple domain controllers and configure redundancy via DNS or load balancing mechanisms.
Place SAP Web Dispatcher or an external reverse proxy in front of your SAP systems to manage incoming authentication traffic.
Implement health checks and failover rules to automatically redirect traffic if a backend system or SLS node becomes unavailable.
Certificate Management
Audit Logging
Monitoring Tools
Keep SSO Infrastructure Separate: Avoid deploying SSO services on the same nodes as application servers to minimize risk and performance bottlenecks.
Use Secure Communication: Enforce HTTPS and encrypted communication for all components, including between clients and the SLS.
Test Failover Scenarios: Regularly simulate failures to validate that the HA configuration works as intended.
Document and Automate Recovery Steps: Automate service restarts and ensure system administrators have clear runbooks for failover scenarios.
SAP Single Sign-On significantly enhances user convenience and security in SAP environments. In high-availability setups, it is essential to architect SSO services with redundancy, load balancing, and robust failover strategies. With proper design, SAP SSO can deliver both seamless access and resilient authentication infrastructure, ensuring business continuity and user productivity even during outages or maintenance events.