Probing helps in measuring the metrics of a channel. A “profile” is a set of probing parameters configured on a device to send a probe packet on a channel that must be monitored. Before sending a probe packets on a channel, the channel that is to be monitored must be understood because each monitor has different profiles. In most cases, there are two monitors—default and quick. Each probe has two parameters, namely, burst packets and burst interval, which can be configured to define the probe packets sent on a PfR channel.

The PfRv3 Probe Reduction feature allows reducing traffic probe on channels that do not carry any traffic. For more information see the PfRv3 Probe Reduction module.

The PfRv3 Probe Reduction feature enforces similar probing on all interfaces irrespective of an interface through which a channel goes out, whereas the PfRv3 Per Interface Probe Tuning feature provides the flexibility to enforce different profiles on channels associated with an interface.

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.

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.

The profiles are associated with the channel and not the interface because it is possible that the same interface may host different channels, especially on border hub routers. If two channels have different profile numbers, the channel with a higher profile number is chosen to transmit data. The profile negotiation rule requires a profile with higher ID number to have a slower probing rate. The default profile (one packet every one second for default monitor and 20 packets every one second for quick monitor) has sufficient probing rate.When a channel probes at a slower rate (bigger profile ID number) another channel in the network probes at a higher rate (smaller profile ID number).

Note	There is no automatic detection mechanism to calculate the rate of different profiles if the profile negotiation rule (higher-ID-slower-rate) is violated.

domain domain1
 border
  advanced
   smart-probe 1 burst quick 10 packets every 20 seconds 1

interface tunnel 100
 domain smart-probe profile 1

The following is a sample output of the show platform software pfrv3 command that displays the profile parameters applied to an device:

HubBr2# show platform software pfrv3 rp active smart-probe
PfRv3 smart probe parameters :
Profile ID: 0
Attribute: 0x0000
Probe Burst interval: 1 second
Probe Burst number: 1 packets
Quick Monitor Probe Burst interval: 1 second
Quick Monitor Probe Burst number: 20 packets
Unreachable interval: 4 second
Profile ID: 1
Attribute: 0x0000
Probe Burst interval: 0 second
Probe Burst number: 0 packets
Quick Monitor Probe Burst interval: 0 second
Quick Monitor Probe Burst number: 0 packets
Unreachable interval: 4 second
Profile ID: 2
Attribute: 0x0000
Probe Burst interval: 0 second
Probe Burst number: 0 packets
Quick Monitor Probe Burst interval: 0 second
Quick Monitor Probe Burst number: 0 packets
Unreachable interval: 4 second

The following is a sample output of the show platform hardware qfp command that displays the profile parameters associated with a channel:

Branch100# show platform hardware qfp active feature pfrv3 client channel id 7 detail
Chan id: 7 tbl-id: 0, if_h: 14(Tunnel100), site-id: 10.3.1.1, in_uidb: 65528, dscp: 0, pfr-label: 0:0 | 0:0 [00000000]
  Supports zero-sla: Yes
  Muted by zero-sla: No
  Plr rx state: No
  Plr tx state: No
  Plr establish state: No
  next hop: 100.1.1.1
  State:    Discovered and open
  rx state: Reachable
  tx state: Reachable
  Smart Probe in Burst: No
  Unreach Probing only: Off
  Profile_ID: 0
  V4 Smart Probe Received: Yes
  V4 Smart Probe Sent: Yes
  Current profile_id: 1 <<< different than "Profile ID" (two lines above), resulted from negotiation
  Remote profile_id: 1
  hash val: 25699
  exmem info:
        PPE addr: 0xebd26000
  stats:
    RX pkts: 0  bytes: 0
    TX pkts: 0  bytes: 0
    Blackhole pkts: 0  bytes: 0
    Loop pkts: 0  bytes: 0
    Probes: rx: 6288 tx: 474
    Number of SMP Profile Bursts sent: 100
    Number of Active Channel Probes sent: 374
    Number of Reachability Probes sent: 0
    Number of Force Unreaches sent: 0
    Last Probe rx: 44115 ms Ago
    Last Probe tx: 3379 ms Ago