The PfRv3 Per Interface Probe Tuning feature is configured on border hub routers via the profile-id argument in the smart-probes command and applied to an interface via the domain smart-probe profile command.
If you do not configure these commands, the default profile 0, is set on a device. The default profile has predefined parameters of 1 packet every 1 second for a default monitor and 20 packets every 1 second for a quick monitor.
The following is a sample topology to explain the working of the PfRv3 Per Interface Probe Tuning feature.
Figure 1. Per Interface Probe Tuning—Sample Topology
A hub branch router communicates to two branch routers Branch 1 Router and Branch 2 Router via ISP. Branch 1 Router has a regular interface, while Branch 2 Router has an Long-Term Evolution (LTE) interface. The LTE interface requires different probing parameters on the channel connected to the interface as LTE radio channels are established when data needs to be transmitted over the interface and radio frequency band occupies the transmission.
The profile parameters for the LTE interface are 100 packets every 1200 seconds for default monitor and default values for quick monitor. The profile parameters for the regular interface is the default parameters, which is, one packet every one second for default monitor and 20 packets every one second for quick monitor.
The hub border router establishes channels through its WAN interface to Branch 1 Router and Branch 2 Router via the ISP. Based on the defined profile parameters, channels from the hub border router to the Branch 1 Router are probed at regular intervals. Channels from the hub border router to Branch 2 Router wil have not have incoming probes for 19 minutes. The following happens before data is transmitted to the LTE interface:
Burst probe packets are sent over the channel to measure the metrics.
The burst interval range is increased to allow a longer duration so that radio bandwidth is not stagnated.
Unreachable probe packets are not sent after sending the burst probe packets. This is to free up the radio bandwidth. to transmit the data.
The burst interval range is configured to a longer duration so that radio bandwidth is not occupied.
Unreachability detection is suppressed to ensure that there is no unreachability from a remote device for a period of time.