In expanded SLA mode, the primary shaper is used to limit the subscriber’s aggregate rate. Multiple SPIs can be associated with a subscriber and each SPI can be individually rate limited. An example of this scenario is shown in Figure: Expanded SLA mode.
In this example, two SPIs are associated with the subscriber (only the details of the SPI1 for subscriber 1 are shown in Figure: Expanded SLA mode). Each SPI is shaped to an aggregate rate while the aggregate rate of the subscriber is shaped by the aggregate rate of the primary shaper. This scaling configuration is limited by the number of available primary shapers per line card. See the scaling figures in the SR OS Scaling Guides.
The access to the aggregate rate of the primary shaper through a subscriber profile in expanded SLA mode is an important distinction between the two modes of operation. In single SLA mode aggregate rate of the primary shaper is not accessible and is set to max (no rate limiting function is performed by the primary shaper).
