1. Essentials Guide
  2. The Session Load Balancer and Route Manager
  3. SLRM Operation
  4. Balancing

Balancing

Balancing is the act of the SLRM maintaining an ordered list of Oracle Communications Core Session Managers to which it sends traffic for a given core.

Having established each Oracle Communications Core Session Manager state, the SLRM groups all Oracle Communications Core Session Managers that service a given core into clusters. The SLRM then establishes load balance lists labeled:

  • Preferred — The administrator has configured both the target Oracle Communications Core Session Manager and the source P-CSCF within the same cluster.
  • Alternative — The target Oracle Communications Core Session Manager and the source P-CSCF are not in the same cluster.

Note:

For single cluster deployments, all Oracle Communications Core Session Managers registered to the SLRM function belong to the default cluster. If all P-CSCFs are in the default cluster, then every Oracle Communications Core Session Manager is "Preferred" for every registration.

Having categorized each Oracle Communications Core Session Manager within their clusters, the SLRM then creates, and on an on-going, dynamic basis using KPIs from SLRM-registration updates, maintains the load balance order as follows:

  • Preferred Oracle Communications Core Session Managers — Sorted by free endpoint capacity.
  • Preferred, Out of Sync Oracle Communications Core Session Manager — Add to the bottom of the preferred list, sorted by free endpoint capacity.
  • Alternative Oracle Communications Core Session Managers — Sort by free endpoint capacity and add to list after all preferred Oracle Communications Core Session Managers.
  • Alternative, Out of Sync Oracle Communications Core Session Manager — Add to the bottom of the alternative list, sorted by free endpoint capacity.

There may be multiple Alternative Oracle Communications Core Session Manager groups. Alternative groups are selected in round-robin fashion.

Free endpoint capacity is calculated as percent utilization based on supported capacity and current utilization. It is reported by the Oracle Communications Core Session Manager to the SLRM via the Sc interface.

SLRM distributes each message individually based on the criteria above. If a message fails at a Oracle Communications Core Session Manager in the list, SLRM proceeds by sending the message to the next Oracle Communications Core Session Manager in the composite list.