Limitations with VoIP SLAs

A maximum of 80 concurrent VoIP SLAs can be scheduled in a 20 second slot.

A single VoIP probe takes 20 seconds to complete.

The default and minimum probe interval for VoIP SLA is 120 seconds.

SLAs scheduled in the same slot, periodically sends 1000 probe packets for 120 seconds in 20 second intervals.

Default 120 second probe interval is divided in to 6 slots of 20 seconds to avoid synchronization of all configured VoIP SLAs sending probes at the same time.

SLAs started at the same time exceeding the concurrent limit of 80 must wait for the next 20 second VoIP slot to open before moving to ‘running’ state.

The maximum number of VoIP SLAs supported is 80 X 6 slots = 480 SLAs.

SLAs exceeding 480 will continue to remain in the 'waiting for VoIP slot' until any slot is freed by stopping the running SLA.

To avoid high RTT, a single switch with more than 20 SLAs should not have single responder SLA.