The SLB introduces a Peer Overload Control functionality. A configurable "neverRetry" option is provided in the system > SLB configuration for regular calls rejected due to congestion. Depending on the Global Utilization, the "neverRetry" flag decision to retry the call, a drop, or 503 relay is made.
On the SBC Main screen go to All > System > SLB > Overload Control Options.
The SBC provides the Utilization Override option to override the weight of the SBC on the SLB.