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SSR Cluster Overview


A standalone SBR Carrier server runs the entire AAA process using local session database processes on a single machine.

The Session State Register (SSR) module implements a stateless, highly reliable and highly available AAA platform. It separates SBR Carrier front end processes from back end data functions that take place on two or four Session State Register data servers.

The SBR Carrier front end and SSR back end servers collaborate to create a virtual AAA server that provides:

  • High availability

  • Session state preserved during failover of front end SBR Carrier nodes

  • Application session awareness

  • Centralized IP address management

  • Concurrency management (if the optional Concurrency and Wholesale Module is installed on all SBR Carrier servers)

To work efficiently and to provide redundancy, a production SSR cluster must be built on a fast, isolated, and redundant network infrastructure. It must include multiple hosts and nodes so a single node failure cannot prevent the cluster from operating.

Because the SSR database contains detailed attributes for each session it serves, it is a logical source for applications that query the AAA environment for correlative and verification purposes. The default SSR database schema addresses standard requirements for most wireless and wireline service providers. You can also customize it to address unique requirements or to support other applications. For example, a video portal or streaming server that has the IP address for a session but requires the user identity attached to the session for billing or personalization. The video gateway can query the SSR database in real time to correlate information about any active session.


The Session State Register Database is not, and cannot be used as, a permanent subscriber database.

RADIUS Class Attributes are part of the RADIUS standard, but not all network access devices (NADs) fully support them. In order for the SSR to reliably track sessions throughout each session’s lifetime, the network NADs must support the RADIUS Class Attributes.