Merge branch '57-finalize' into stage

content/cumulus-linux-57/System-Configuration/Date-and-Time/Precision Time Protocol-PTP.md

@@ -484,6 +484,144 @@ cumulus@switch:~$ sudo systemctl restart ptp4l.service
 {{< /tab >}}
 {{< /tabs >}}
 
+### Noise Transfer Servo
+
+ITU-T specifies the following key elements to measure, test, and classify the accuracy of a clock:
+- Noise generation&mdash;jitter and wander noise in the output of a clock in reference to a <span style="background-color:#F5F5DC">[PRTC](## "Primary Reference Time Clock")</span>.
+- Noise tolerance&mdash;how much noise the clock can tolerate before it switches to another stable source.
+- Noise transfer&mdash;smoothe out the input noise so that noise does not accumulate and increase over a network of clocks.
+- Transient response&mdash;the response from the clock to a transient.
+- Hold over&mdash;the time interval during which the clock maintains its output after losing the input reference signal.
+
+Cumulus Linux PTP has an option to use a servo specifically designed to handle ITU-T’s Noise Transfer specification. When you use this option, the <span style="background-color:#F5F5DC">[PHC](## "Physical Hardware Clock")</span> is disciplined by Noise Transfer Servo, which smoothes the jitter and wander noise from the Master clock.
+
+{{%notice note%}}
+- To use Noise Transfer Servo, you need to enable SyncE on the switch and on PTP interfaces. 
+- Cumulus Linux supports Noise Transfer Servo on Spectrum ASICs that support SyncE.
+- NVIDIA recommends you do not change the default Noise Transfer Servo configuration parameters.
+- NVIDIA recommends you use Noise Transfer Servo with PTP Telecom profiles. If you use other profiles or choose not to use a profile, make sure to set the sync interval to -3 or better.
+{{%/notice%}}
+
+To enable Noise Transfer Servo:
+
+{{< tabs "TabID500 ">}}
+{{< tab "NVUE Commands ">}}
+
+The following example enables PTP, sets the profile to `default-itu-8275-1`, enables SyncE, enables PTP on swp3, and enables Noise Transfer Servo.
+
+```
+cumulus@switch:~$ nv set service ptp 1 enable on
+cumulus@switch:~$ nv set service ptp 1 current-profile default-itu-8275-1
+cumulus@switch:~$ nv set system synce enable on
+cumulus@switch:~$ nv set interface swp3 ptp enable on
+cumulus@switch:~$ nv set service ptp 1 servo noise-transfer
+cumulus@switch:~$ nv config apply
+```
+
+{{< /tab >}}
+{{< tab "Linux Commands ">}}
+
+Edit the `/etc/ptp4l.conf` and the `/etc/firefly_servo/servo.conf` files; see examples below.
+
+```
+cumulus@switch:~$ sudo nano /etc/ptp4l.conf
+[global]
+#
+# Default Data Set
+#
+slaveOnly                      0
+free_running                   1
+slave_event_monitor            /var/run/servo_slave_event_monitor
+priority1                      128
+priority2                      128
+domainNumber                   24
+
+twoStepFlag                    1
+dscp_event                     46
+dscp_general                   46
+network_transport              L2
+dataset_comparison             G.8275.x
+G.8275.defaultDS.localPriority 128
+ptp_dst_mac                    01:80:C2:00:00:0E
+#
+# Port Data Set
+#
+logAnnounceInterval            -3
+logSyncInterval                -4
+logMinDelayReqInterval         -4
+announceReceiptTimeout         3
+delay_mechanism                E2E
+
+offset_from_master_min_threshold   -50
+offset_from_master_max_threshold   50
+mean_path_delay_threshold          200
+tsmonitor_num_ts                   100
+tsmonitor_num_log_sets             2
+tsmonitor_num_log_entries          4
+tsmonitor_log_wait_seconds         1
+#
+# Run time options
+#
+logging_level                  6
+path_trace_enabled             0
+use_syslog                     1
+verbose                        0
+summary_interval               0
+#
+# servo parameters
+#
+pi_proportional_const          0.000000
+pi_integral_const              0.000000
+pi_proportional_scale          0.700000
+pi_proportional_exponent       -0.300000
+pi_proportional_norm_max       0.700000
+pi_integral_scale              0.300000
+pi_integral_exponent           0.400000
+pi_integral_norm_max           0.300000
+first_step_threshold           0.000020
+step_threshold                 0.000000025
+servo_offset_threshold         20
+servo_num_offset_values        10
+write_phase_mode               1
+max_frequency                  50000000
+sanity_freq_limit              0
+#
+# Default interface options
+#
+time_stamping                  hardware
+
+[swp3]
+udp_ttl                      1
+masterOnly                   0
+delay_mechanism              E2E
+```
+
+```
+cumulus@switch:~$ sudo nano /etc/firefly_servo/servo.conf
+[global]
+free_running                        0
+domainNumber                        24
+
+offset_from_master_min_threshold    -50
+offset_from_master_max_threshold    50
+
+# Debugging & Logging
+doca_logging_level                  50
+
+init_max_time_adjustment            0
+max_time_adjustment                 1500
+hold_over_timer                     0
+# Sampling Window & servo logic
+servo_window_timer                  3000
+servo_window_min_samples            10
+servo_num_offset_values             5
+```
+
+{{< /tab >}}
+{{< /tabs >}}
+
+To show Noise Transfer Servo configuration settings, run the `nv show service ptp <instance-id> servo` command.
+
 ## Optional Global Configuration
 
 Optional global PTP configuration includes configuring the DiffServ code point (DSCP). You can configure the DSCP value for all PTP IPv4 packets originated locally. You can set a value between 0 and 63.