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Chapter 11. Using PTP hardware

Important

Precision Time Protocol (PTP) hardware with single NIC configured as boundary clock is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

11.1. About PTP hardware

OpenShift Container Platform allows you use PTP hardware on your nodes. You can configure linuxptp services on nodes that have PTP-capable hardware.

Note

The PTP Operator works with PTP-capable devices on clusters provisioned only on bare-metal infrastructure.

You can use the OpenShift Container Platform console or oc CLI to install PTP by deploying the PTP Operator. The PTP Operator creates and manages the linuxptp services and provides the following features:

  • Discovery of the PTP-capable devices in the cluster.
  • Management of the configuration of linuxptp services.
  • Notification of PTP clock events that negatively affect the performance and reliability of your application with the PTP Operator cloud-event-proxy sidecar.

11.2. About PTP

The Precision Time Protocol (PTP) is used to synchronize clocks in a network. When used in conjunction with hardware support, PTP is capable of sub-microsecond accuracy, and is more accurate than Network Time Protocol (NTP).

The linuxptp package includes the ptp4l and phc2sys programs for clock synchronization. ptp4l implements the PTP boundary clock and ordinary clock. ptp4l synchronizes the PTP hardware clock to the source clock with hardware time stamping and synchronizes the system clock to the source clock with software time stamping. phc2sys is used for hardware time stamping to synchronize the system clock to the PTP hardware clock on the network interface controller (NIC).

11.2.1. Elements of a PTP domain

PTP is used to synchronize multiple nodes connected in a network, with clocks for each node. The following type of clocks can be included in configurations:

Grandmaster clock
The grandmaster clock provides standard time information to other clocks across the network and ensures accurate and stable synchronisation. The grandmaster clock writes time stamps and responds to time requests from other clocks.
Ordinary clock
The ordinary clock has a single port connection that can play the role of source or destination clock, depending on its position in the network. The ordinary clock can read and write time stamps.
Boundary clock
The boundary clock has ports in two or more communication paths and can be a source and a destination to other destination clocks at the same time. The boundary clock works as a destination clock upstream. The destination clock receives the timing message, adjusts for delay, and then creates a new source time signal to pass down the network. The boundary clock produces a new timing packet that is still correctly synced with the source clock and can reduce the number of connected devices reporting directly to the source clock.

11.2.2. Advantages of PTP over NTP

One of the main advantages that PTP has over NTP is the hardware support present in various network interface controllers (NIC) and network switches. The specialized hardware allows PTP to account for delays in message transfer and improves the accuracy of time synchronization. To achieve the best possible accuracy, it is recommended that all networking components between PTP clocks are PTP hardware enabled.

Hardware-based PTP provides optimal accuracy, since the NIC can time stamp the PTP packets at the exact moment they are sent and received. Compare this to software-based PTP, which requires additional processing of the PTP packets by the operating system.

Important

Before enabling PTP, ensure that NTP is disabled for the required nodes. You can disable the chrony time service (chronyd) using a MachineConfig custom resource. For more information, see Disabling chrony time service.

11.3. Installing the PTP Operator using the CLI

As a cluster administrator, you can install the Operator by using the CLI.

Prerequisites

  • A cluster installed on bare-metal hardware with nodes that have hardware that supports PTP.
  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.

Procedure

  1. To create a namespace for the PTP Operator, enter the following command: 

    $ cat << EOF| oc create -f -
apiVersion: v1
kind: Namespace
metadata:
  name: openshift-ptp
  annotations:
    workload.openshift.io/allowed: management
  labels:
    name: openshift-ptp
    openshift.io/cluster-monitoring: "true"
EOF

  2. To create an Operator group for the Operator, enter the following command: 

    $ cat << EOF| oc create -f -
apiVersion: operators.coreos.com/v1
kind: OperatorGroup
metadata:
  name: ptp-operators
  namespace: openshift-ptp
spec:
  targetNamespaces:
  - openshift-ptp
EOF

  3. Subscribe to the PTP Operator.

    1. Run the following command to set the OpenShift Container Platform major and minor version as an environment variable, which is used as the channel value in the next step. 

      $ OC_VERSION=$(oc version -o yaml | grep openshiftVersion | \
    grep -o '[0-9]*[.][0-9]*' | head -1)

    2. To create a subscription for the PTP Operator, enter the following command: 

      $ cat << EOF| oc create -f -
apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
  name: ptp-operator-subscription
  namespace: openshift-ptp
spec:
  channel: "${OC_VERSION}"
  name: ptp-operator
  source: redhat-operators
  sourceNamespace: openshift-marketplace
EOF

  4. To verify that the Operator is installed, enter the following command: 

    $ oc get csv -n openshift-ptp \
  -o custom-columns=Name:.metadata.name,Phase:.status.phase

    Example output

    Name                                        Phase
ptp-operator.4.4.0-202006160135             Succeeded

11.4. Installing the PTP Operator using the web console

As a cluster administrator, you can install the PTP Operator using the web console.

Note

You have to create the namespace and Operator group as mentioned in the previous section.

Procedure

  1. Install the PTP Operator using the OpenShift Container Platform web console:

    1. In the OpenShift Container Platform web console, click Operators OperatorHub.
    2. Choose PTP Operator from the list of available Operators, and then click Install.
    3. On the Install Operator page, under A specific namespace on the cluster select openshift-ptp. Then, click Install.

  2. Optional: Verify that the PTP Operator installed successfully:

    1. Switch to the Operators Installed Operators page.

    2. Ensure that PTP Operator is listed in the openshift-ptp project with a Status of InstallSucceeded.

      Note

      During installation an Operator might display a Failed status. If the installation later succeeds with an InstallSucceeded message, you can ignore the Failed message.

      If the Operator does not appear as installed, to troubleshoot further:

      • Go to the Operators Installed Operators page and inspect the Operator Subscriptions and Install Plans tabs for any failure or errors under Status.
      • Go to the Workloads Pods page and check the logs for pods in the openshift-ptp project.

11.5. Automated discovery of PTP network devices

The PTP Operator adds the NodePtpDevice.ptp.openshift.io custom resource definition (CRD) to OpenShift Container Platform.

The PTP Operator searchs your cluster for PTP-capable network devices on each node. It creates and updates a NodePtpDevice custom resource (CR) object for each node that provides a compatible PTP device.

One CR is created for each node and shares the same name as the node. The .status.devices list provides information about the PTP devices on a node.

The following is an example of a NodePtpDevice CR created by the PTP Operator: 

apiVersion: ptp.openshift.io/v1
kind: NodePtpDevice
metadata:
  creationTimestamp: "2019-11-15T08:57:11Z"
  generation: 1
  name: dev-worker-0 1
  namespace: openshift-ptp 2
  resourceVersion: "487462"
  selfLink: /apis/ptp.openshift.io/v1/namespaces/openshift-ptp/nodeptpdevices/dev-worker-0
  uid: 08d133f7-aae2-403f-84ad-1fe624e5ab3f
spec: {}
status:
  devices: 3
  - name: eno1
  - name: eno2
  - name: ens787f0
  - name: ens787f1
  - name: ens801f0
  - name: ens801f1
  - name: ens802f0
  - name: ens802f1
  - name: ens803
1
The value for the name parameter is the same as the name of the node.
2
The CR is created in openshift-ptp namespace by PTP Operator.
3
The devices collection includes a list of the PTP capable devices discovered by the Operator on the node.

To return a complete list of PTP capable network devices in your cluster, run the following command: 

$ oc get NodePtpDevice -n openshift-ptp -o yaml

11.6. Configuring linuxptp services as ordinary clock

The PTP Operator adds the PtpConfig.ptp.openshift.io custom resource definition (CRD) to OpenShift Container Platform. You can configure the linuxptp services (ptp4l, phc2sys) by creating a PtpConfig custom resource (CR) object.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.
  • Install the PTP Operator.

Procedure

  1. Create the following PtpConfig CR, and then save the YAML in the ordinary-clock-ptp-config.yaml file. 

    apiVersion: ptp.openshift.io/v1
kind: PtpConfig
metadata:
  name: ordinary-clock-ptp-config 1
  namespace: openshift-ptp
spec:
  profile: 2
  - name: "profile1" 3
    interface: "ens787f1" 4
    ptp4lOpts: "-s -2" 5
    phc2sysOpts: "-a -r" 6
    ptp4lConf: "" 7
    ptpSchedulingPolicy: SCHED_OTHER 8
    ptpSchedulingPriority: 10 9
  recommend: 10
  - profile: "profile1" 11
    priority: 10 12
    match: 13
    - nodeLabel: "node-role.kubernetes.io/worker" 14
      nodeName: "compute-0.example.com" 15
    1
    The name of the PtpConfig CR.
    2
    Specify an array of one or more profile objects.
    3
    Specify the name of a profile object that uniquely identifies a profile object.
    4
    Specify the network interface name to use by the ptp4l service, for example ens787f1.
    5
    Specify system config options for the ptp4l service, for example -2 to select the IEEE 802.3 network transport. The options should not include the network interface name -i <interface> and service config file -f /etc/ptp4l.conf because the network interface name and the service config file are automatically appended.
    6
    Specify system config options for the phc2sys service, for example -a -r. If this field is empty the PTP Operator does not start the phc2sys service.
    7
    Specify a string that contains the configuration to replace the default /etc/ptp4l.conf file. To use the default configuration, leave the field empty.
    8
    Scheduling policy for ptp4l and phc2sys processes. Default value is SCHED_OTHER. Use SCHED_FIFO on systems that support FIFO scheduling.
    9
    Integer value from 1-65 used to set FIFO priority for ptp4l and phc2sys processes when ptpSchedulingPolicy is set to SCHED_FIFO. The ptpSchedulingPriority field is not used when ptpSchedulingPolicy is set to SCHED_OTHER.
    10
    Specify an array of one or more recommend objects that define rules on how the profile should be applied to nodes.
    11
    Specify the profile object name defined in the profile section.
    12
    Specify the priority with an integer value between 0 and 99. A larger number gets lower priority, so a priority of 99 is lower than a priority of 10. If a node can be matched with multiple profiles according to rules defined in the match field, the profile with the higher priority is applied to that node.
    13
    Specify match rules with nodeLabel or nodeName.
    14
    Specify nodeLabel with the key of node.Labels from the node object by using the oc get nodes --show-labels command.
    15
    Specify nodeName with node.Name from the node object by using the oc get nodes command.

  2. Create the CR by running the following command: 

    $ oc create -f ordinary-clock-ptp-config.yaml

Verification steps

  1. Check that the PtpConfig profile is applied to the node.

    1. Get the list of pods in the openshift-ptp namespace by running the following command: 

      $ oc get pods -n openshift-ptp -o wide

      Example output

      NAME                            READY   STATUS    RESTARTS   AGE   IP               NODE
linuxptp-daemon-4xkbb           1/1     Running   0          43m   10.1.196.24      compute-0.example.com
linuxptp-daemon-tdspf           1/1     Running   0          43m   10.1.196.25      compute-1.example.com
ptp-operator-657bbb64c8-2f8sj   1/1     Running   0          43m   10.129.0.61      control-plane-1.example.com

    2. Check that the profile is correct. Examine the logs of the linuxptp daemon that corresponds to the node you specified in the PtpConfig profile. Run the following command: 

      $ oc logs linuxptp-daemon-4xkbb -n openshift-ptp -c linuxptp-daemon-container

      Example output

      I1115 09:41:17.117596 4143292 daemon.go:107] in applyNodePTPProfile
I1115 09:41:17.117604 4143292 daemon.go:109] updating NodePTPProfile to:
I1115 09:41:17.117607 4143292 daemon.go:110] ------------------------------------
I1115 09:41:17.117612 4143292 daemon.go:102] Profile Name: profile1
I1115 09:41:17.117616 4143292 daemon.go:102] Interface: ens787f1
I1115 09:41:17.117620 4143292 daemon.go:102] Ptp4lOpts: -s -2
I1115 09:41:17.117623 4143292 daemon.go:102] Phc2sysOpts: -a -r
I1115 09:41:17.117626 4143292 daemon.go:116] ------------------------------------

Additional resources

11.7. Configuring linuxptp services as boundary clock

The PTP Operator adds the PtpConfig.ptp.openshift.io custom resource definition (CRD) to OpenShift Container Platform. You can configure the linuxptp services (ptp4l, phc2sys) by creating a PtpConfig custom resource (CR) object.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.
  • Install the PTP Operator.

Procedure

  1. Create the following PtpConfig CR, and then save the YAML in the boundary-clock-ptp-config.yaml file. 

    apiVersion: ptp.openshift.io/v1
kind: PtpConfig
metadata:
  name: boundary-clock-ptp-config 1
  namespace: openshift-ptp
spec:
  profile: 2
  - name: "profile1" 3
    interface: "" 4
    ptp4lOpts: "-2" 5
    ptp4lConf: | 6
      [ens1f0] 7
      masterOnly 0
      [ens1f3] 8
      masterOnly 1
      [global]
      #
      # Default Data Set
      #
      twoStepFlag                       1
      #slaveOnly                        1
      priority1                         128
      priority2                         128
      domainNumber                      24
      #utc_offset                       37
      clockClass                        248
      clockAccuracy                     0xFE
      offsetScaledLogVariance         0xFFFF
      free_running                      0
      freq_est_interval               1
      dscp_event                        0
      dscp_general                      0
      dataset_comparison              G.8275.x
      G.8275.defaultDS.localPriority  128
      #
      # Port Data Set
      #
      logAnnounceInterval          -3
      logSyncInterval                -4
      logMinDelayReqInterval       -4
      logMinPdelayReqInterval      -4
      announceReceiptTimeout       3
      syncReceiptTimeout           0
      delayAsymmetry                 0
      fault_reset_interval         4
      neighborPropDelayThresh      20000000
      masterOnly                     0
      G.8275.portDS.localPriority  128
      #
      # Run time options
      #
      assume_two_step              0
      logging_level                6
      path_trace_enabled         0
      follow_up_info               0
      hybrid_e2e                   0
      inhibit_multicast_service  0
      net_sync_monitor           0
      tc_spanning_tree           0
      tx_timestamp_timeout       10
      #was 1 (default !)
      unicast_listen          0
      unicast_master_table  0
      unicast_req_duration  3600
      use_syslog              1
      verbose                   0
      summary_interval      -4
      kernel_leap             1
      check_fup_sync          0
      #
      # Servo Options
      #
      pi_proportional_const     0.0
      pi_integral_const         0.0
      pi_proportional_scale     0.0
      pi_proportional_exponent  -0.3
      pi_proportional_norm_max  0.7
      pi_integral_scale         0.0
      pi_integral_exponent      0.4
      pi_integral_norm_max      0.3
      step_threshold            2.0
      first_step_threshold      0.00002
      max_frequency               900000000
      clock_servo                 pi
      sanity_freq_limit         200000000
      ntpshm_segment              0
      #
      # Transport options
      #
      transportSpecific   0x0
      ptp_dst_mac          01:1B:19:00:00:00
      p2p_dst_mac          01:80:C2:00:00:0E
      udp_ttl                1
      udp6_scope           0x0E
      uds_address          /var/run/ptp4l
      #
      # Default interface options
      #
      clock_type             BC
      network_transport    UDPv4
      delay_mechanism        E2E
      time_stamping          hardware
      tsproc_mode            filter
      delay_filter           moving_median
      delay_filter_length  10
      egressLatency          0
      ingressLatency         0
      boundary_clock_jbod  0 9
      #
      # Clock description
      #
      productDescription    ;;
      revisionData            ;;
      manufacturerIdentity  00:00:00
      userDescription         ;
      timeSource              0xA0
    phc2sysOpts: "-a -r" 10
    ptpSchedulingPolicy: SCHED_OTHER 11
    ptpSchedulingPriority: 10 12
  recommend: 13
  - profile: "profile1" 14
    priority: 10 15
    match: 16
    - nodeLabel: "node-role.kubernetes.io/worker" 17
      nodeName: "compute-0.example.com" 18
    1
    The name of the PtpConfig CR.
    2
    Specify an array of one or more profile objects.
    3
    Specify the name of a profile object which uniquely identifies a profile object.
    4
    This field should remain empty for boundary clock.
    5
    Specify system config options for the ptp4l service, for example -2. The options should not include the network interface name -i <interface> and service config file -f /etc/ptp4l.conf because the network interface name and the service config file are automatically appended.
    6
    Specify the needed configuration to start ptp4l as boundary clock. For example, ens1f0 synchronizes from a grandmaster clock and ens1f3 synchronizes connected devices.
    7
    The interface name to synchronize from.
    8
    The interface to synchronize devices connected to the interface.
    9
    For Intel Columbiaville 800 Series NICs, ensure boundary_clock_jbod is set to 0. For Intel Fortville X710 Series NICs, ensure boundary_clock_jbod is set to 1.
    10
    Specify system config options for the phc2sys service, for example -a -r. If this field is empty the PTP Operator does not start the phc2sys service.
    11
    Scheduling policy for ptp4l and phc2sys processes. Default value is SCHED_OTHER. Use SCHED_FIFO on systems that support FIFO scheduling.
    12
    Integer value from 1-65 used to set FIFO priority for ptp4l and phc2sys processes when ptpSchedulingPolicy is set to SCHED_FIFO. The ptpSchedulingPriority field is not used when ptpSchedulingPolicy is set to SCHED_OTHER.
    13
    Specify an array of one or more recommend objects that define rules on how the profile should be applied to nodes.
    14
    Specify the profile object name defined in the profile section.
    15
    Specify the priority with an integer value between 0 and 99. A larger number gets lower priority, so a priority of 99 is lower than a priority of 10. If a node can be matched with multiple profiles according to rules defined in the match field, the profile with the higher priority is applied to that node.
    16
    Specify match rules with nodeLabel or nodeName.
    17
    Specify nodeLabel with the key of node.Labels from the node object by using the oc get nodes --show-labels command.
    18
    Specify nodeName with node.Name from the node object by using the oc get nodes command.

  2. Create the CR by running the following command: 

    $ oc create -f boundary-clock-ptp-config.yaml

Verification steps

  1. Check that the PtpConfig profile is applied to the node.

    1. Get the list of pods in the openshift-ptp namespace by running the following command: 

      $ oc get pods -n openshift-ptp -o wide

      Example output

      NAME                            READY   STATUS    RESTARTS   AGE   IP               NODE
linuxptp-daemon-4xkbb           1/1     Running   0          43m   10.1.196.24      compute-0.example.com
linuxptp-daemon-tdspf           1/1     Running   0          43m   10.1.196.25      compute-1.example.com
ptp-operator-657bbb64c8-2f8sj   1/1     Running   0          43m   10.129.0.61      control-plane-1.example.com

    2. Check that the profile is correct. Examine the logs of the linuxptp daemon that corresponds to the node you specified in the PtpConfig profile. Run the following command: 

      $ oc logs linuxptp-daemon-4xkbb -n openshift-ptp -c linuxptp-daemon-container

      Example output

      I1115 09:41:17.117596 4143292 daemon.go:107] in applyNodePTPProfile
I1115 09:41:17.117604 4143292 daemon.go:109] updating NodePTPProfile to:
I1115 09:41:17.117607 4143292 daemon.go:110] ------------------------------------
I1115 09:41:17.117612 4143292 daemon.go:102] Profile Name: profile1
I1115 09:41:17.117616 4143292 daemon.go:102] Interface:
I1115 09:41:17.117620 4143292 daemon.go:102] Ptp4lOpts: -2
I1115 09:41:17.117623 4143292 daemon.go:102] Phc2sysOpts: -a -r
I1115 09:41:17.117626 4143292 daemon.go:116] ------------------------------------

Additional resources

11.8. Configuring FIFO priority scheduling for PTP hardware

In telco or other deployment configurations that require low latency performance, PTP daemon threads run in a constrained CPU footprint alongside the rest of the infrastructure components. By default, PTP threads run with the SCHED_OTHER policy. Under high load, these threads might not get the scheduling latency they require for error-free operation.

To mitigate against potential scheduling latency errors, you can configure the PTP Operator linuxptp services to allow threads to run with a SCHED_FIFO policy. If SCHED_FIFO is set for a PtpConfig CR, then ptp4l and phc2sys will run in the parent container under chrt with a priority set by the ptpSchedulingPriority field of the PtpConfig CR.

Note

Setting ptpSchedulingPolicy is optional, and is only required if you are experiencing latency errors.

Procedure

  1. Edit the PtpConfig CR profile: 

    $ oc edit PtpConfig -n openshift-ptp

  2. Change the ptpSchedulingPolicy and ptpSchedulingPriority fields: 

    apiVersion: ptp.openshift.io/v1
kind: PtpConfig
metadata:
  name: <ptp_config_name>
  namespace: openshift-ptp
...
spec:
  profile:
  - name: "profile1"
...
    ptpSchedulingPolicy: SCHED_FIFO 1
    ptpSchedulingPriority: 10 2
    1
    Scheduling policy for ptp4l and phc2sys processes. Use SCHED_FIFO on systems that support FIFO scheduling.
    2
    Required. Sets the integer value 1-65 used to configure FIFO priority for ptp4l and phc2sys processes.
  3. Save and exit to apply the changes to the PtpConfig CR.

Verification

  1. Get the name of the linuxptp-daemon pod and corresponding node where the PtpConfig CR has been applied: 

    $ oc get pods -n openshift-ptp -o wide

    Example output

    NAME                            READY   STATUS    RESTARTS   AGE     IP            NODE
linuxptp-daemon-gmv2n           3/3     Running   0          1d17h   10.1.196.24   compute-0.example.com
linuxptp-daemon-lgm55           3/3     Running   0          1d17h   10.1.196.25   compute-1.example.com
ptp-operator-3r4dcvf7f4-zndk7   1/1     Running   0          1d7h    10.129.0.61   control-plane-1.example.com

  2. Check that the ptp4l process is running with the updated chrt FIFO priority: 

    $ oc -n openshift-ptp logs linuxptp-daemon-lgm55 -c linuxptp-daemon-container|grep chrt

    Example output

    I1216 19:24:57.091872 1600715 daemon.go:285] /bin/chrt -f 65 /usr/sbin/ptp4l -f /var/run/ptp4l.0.config -2  --summary_interval -4 -m

11.9. Troubleshooting common PTP Operator issues

Troubleshoot common problems with the PTP Operator by performing the following steps.

Prerequisites

  • Install the OpenShift Container Platform CLI (oc).
  • Log in as a user with cluster-admin privileges.
  • Install the PTP Operator on a bare-metal cluster with hosts that support PTP.

Procedure

  1. Check the Operator and operands are successfully deployed in the cluster for the configured nodes. 

    $ oc get pods -n openshift-ptp -o wide

    Example output

    NAME                            READY   STATUS    RESTARTS   AGE     IP            NODE
linuxptp-daemon-lmvgn           3/3     Running   0          4d17h   10.1.196.24   compute-0.example.com
linuxptp-daemon-qhfg7           3/3     Running   0          4d17h   10.1.196.25   compute-1.example.com
ptp-operator-6b8dcbf7f4-zndk7   1/1     Running   0          5d7h    10.129.0.61   control-plane-1.example.com

    Note

    When the PTP fast event bus is enabled, the number of ready linuxptp-daemon pods is 3/3. If the PTP fast event bus is not enabled, 2/2 is displayed.

  2. Check that supported hardware is found in the cluster. 

    $ oc -n openshift-ptp get nodeptpdevices.ptp.openshift.io

    Example output

    NAME                                  AGE
control-plane-0.example.com           10d
control-plane-1.example.com           10d
compute-0.example.com                 10d
compute-1.example.com                 10d
compute-2.example.com                 10d

  3. Check the available PTP network interfaces for a node: 

    $ oc -n openshift-ptp get nodeptpdevices.ptp.openshift.io <node_name> -o yaml

    where:

    <node_name>

    Specifies the node you want to query, for example, compute-0.example.com.

    Example output

    apiVersion: ptp.openshift.io/v1
kind: NodePtpDevice
metadata:
  creationTimestamp: "2021-09-14T16:52:33Z"
  generation: 1
  name: compute-0.example.com
  namespace: openshift-ptp
  resourceVersion: "177400"
  uid: 30413db0-4d8d-46da-9bef-737bacd548fd
spec: {}
status:
  devices:
  - name: eno1
  - name: eno2
  - name: eno3
  - name: eno4
  - name: enp5s0f0
  - name: enp5s0f1

  4. Check that the PTP interface is successfully synchronized to the primary clock by accessing the linuxptp-daemon pod for the corresponding node.

    1. Get the name of the linuxptp-daemon pod and corresponding node you want to troubleshoot by running the following command: 

      $ oc get pods -n openshift-ptp -o wide

      Example output

      NAME                            READY   STATUS    RESTARTS   AGE     IP            NODE
linuxptp-daemon-lmvgn           3/3     Running   0          4d17h   10.1.196.24   compute-0.example.com
linuxptp-daemon-qhfg7           3/3     Running   0          4d17h   10.1.196.25   compute-1.example.com
ptp-operator-6b8dcbf7f4-zndk7   1/1     Running   0          5d7h    10.129.0.61   control-plane-1.example.com

    2. Remote shell into the required linuxptp-daemon container: 

      $ oc rsh -n openshift-ptp -c linuxptp-daemon-container <linux_daemon_container>

      where:

      <linux_daemon_container>
      is the container you want to diagnose, for example linuxptp-daemon-lmvgn.

    3. In the remote shell connection to the linuxptp-daemon container, use the PTP Management Client (pmc) tool to diagnose the network interface. Run the following pmc command to check the sync status of the PTP device, for example ptp4l. 

      # pmc -u -f /var/run/ptp4l.0.config -b 0 'GET PORT_DATA_SET'

      Example output when the node is successfully synced to the primary clock

      sending: GET PORT_DATA_SET
    40a6b7.fffe.166ef0-1 seq 0 RESPONSE MANAGEMENT PORT_DATA_SET
        portIdentity            40a6b7.fffe.166ef0-1
        portState               SLAVE
        logMinDelayReqInterval  -4
        peerMeanPathDelay       0
        logAnnounceInterval     -3
        announceReceiptTimeout  3
        logSyncInterval         -4
        delayMechanism          1
        logMinPdelayReqInterval -4
        versionNumber           2

11.10. PTP hardware fast event notifications framework

Important

PTP events with ordinary clock is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

11.10.1. About PTP and clock synchronization error events

Cloud native applications such as virtual RAN require access to notifications about hardware timing events that are critical to the functioning of the overall network. Fast event notifications are early warning signals about impending and real-time Precision Time Protocol (PTP) clock synchronization events. PTP clock synchronization errors can negatively affect the performance and reliability of your low latency application, for example, a vRAN application running in a distributed unit (DU).

Loss of PTP synchronization is a critical error for a RAN network. If synchronization is lost on a node, the radio might be shut down and the network Over the Air (OTA) traffic might be shifted to another node in the wireless network. Fast event notifications mitigate against workload errors by allowing cluster nodes to communicate PTP clock sync status to the vRAN application running in the DU.

Event notifications are available to RAN applications running on the same DU node. A publish/subscribe REST API passes events notifications to the messaging bus. Publish/subscribe messaging, or pub/sub messaging, is an asynchronous service to service communication architecture where any message published to a topic is immediately received by all the subscribers to the topic.

Fast event notifications are generated by the PTP Operator in OpenShift Container Platform for every PTP-capable network interface. The events are made available using a cloud-event-proxy sidecar container over an Advanced Message Queuing Protocol (AMQP) message bus. The AMQP message bus is provided by the AMQ Interconnect Operator.

Note

PTP fast event notifications are available only for network interfaces configured to use PTP ordinary clocks.

11.10.2. About the PTP fast event notifications framework

You can subscribe Distributed unit (DU) applications to Precision Time Protocol (PTP) fast events notifications that are generated by OpenShift Container Platform with the PTP Operator and cloud-event-proxy sidecar container. You enable the cloud-event-proxy sidecar container by setting the enableEventPublisher field to true in the ptpOperatorConfig custom resource (CR) and specifying a transportHost address. PTP fast events use an Advanced Message Queuing Protocol (AMQP) event notification bus provided by the AMQ Interconnect Operator. AMQ Interconnect is a component of Red Hat AMQ, a messaging router that provides flexible routing of messages between any AMQP-enabled endpoints.

The cloud-event-proxy sidecar container can access the same resources as the primary vRAN application without using any of the resources of the primary application and with no significant latency.

The fast events notifications framework uses a REST API for communication and is based on the O-RAN REST API specification. The framework consists of a publisher, subscriber, and an AMQ messaging bus to handle communications between the publisher and subscriber applications. The cloud-event-proxy sidecar is a utility container that runs in a pod that is loosely coupled to the main DU application container on the DU node. It provides an event publishing framework that allows you to subscribe DU applications to published PTP events.

DU applications run the cloud-event-proxy container in a sidecar pattern to subscribe to PTP events. The following workflow describes how a DU application uses PTP fast events:

  1. DU application requests a subscription: The DU sends an API request to the cloud-event-proxy sidecar to create a PTP events subscription. The cloud-event-proxy sidecar creates a subscription resource.
  2. cloud-event-proxy sidecar creates the subscription: The event resource is persisted by the cloud-event-proxy sidecar. The cloud-event-proxy sidecar container sends an acknowledgment with an ID and URL location to access the stored subscription resource. The sidecar creates an AMQ messaging listener protocol for the resource specified in the subscription.
  3. DU application receives the PTP event notification: The cloud-event-proxy sidecar container listens to the address specified in the resource qualifier. The DU events consumer processes the message and passes it to the return URL specified in the subscription.
  4. cloud-event-proxy sidecar validates the PTP event and posts it to the DU application: The cloud-event-proxy sidecar receives the event, unwraps the cloud events object to retrieve the data, and fetches the return URL to post the event back to the DU consumer application.
  5. DU application uses the PTP event: The DU application events consumer receives and processes the PTP event.

11.10.3. Installing the AMQ messaging bus

To pass PTP fast event notifications between publisher and subscriber on a node, you must install and configure an AMQ messaging bus to run locally on the node. You do this by installing the AMQ Interconnect Operator for use in the cluster.

Prerequisites

  • Install the OpenShift Container Platform CLI (oc).
  • Log in as a user with cluster-admin privileges.

Procedure

Verification

  1. Check that the AMQ Interconnect Operator is available and the required pods are running: 

    $ oc get pods -n amq-interconnect

    Example output

    NAME                                    READY   STATUS    RESTARTS   AGE
amq-interconnect-645db76c76-k8ghs       1/1     Running   0          23h
interconnect-operator-5cb5fc7cc-4v7qm   1/1     Running   0          23h

  2. Check that the required linuxptp-daemon PTP event producer pods are running in the openshift-ptp namespace. 

    $ oc get pods -n openshift-ptp

    Example output

    NAME                     READY   STATUS    RESTARTS       AGE
linuxptp-daemon-2t78p    3/3     Running   0              12h
linuxptp-daemon-k8n88    3/3     Running   0              12h

11.10.4. Configuring the PTP fast event notifications publisher

To start using PTP fast event notifications for a network interface in your cluster, you must enable the fast event publisher in the PTP Operator PtpOperatorConfig custom resource (CR) and configure ptpClockThreshold values in a PtpConfig CR that you create.

Prerequisites

  • Install the OpenShift Container Platform CLI (oc).
  • Log in as a user with cluster-admin privileges.
  • Install the PTP Operator and AMQ Interconnect Operator.

Procedure

  1. Modify the spec.ptpEventConfig field of the PtpOperatorConfig resource and set appropriate values by running the following command: 

    $ oc edit PtpOperatorConfig default -n openshift-ptp
    ...
spec:
  daemonNodeSelector:
    node-role.kubernetes.io/worker: ""
  ptpEventConfig:
    enableEventPublisher: true 1
    transportHost: amqp://<instance_name>.<namespace>.svc.cluster.local 2
    1
    Set enableEventPublisher to true to enable PTP fast event notifications.
    2
    Set transportHost to the AMQ router you configured where <instance_name> and <namespace> correspond to the AMQ Interconnect router instance name and namespace, for example, amqp://amq-interconnect.amq-interconnect.svc.cluster.local

  2. Create a PtpConfig custom resource for the PTP enabled interface, and set the required values for ptpClockThreshold, for example: 

    apiVersion: ptp.openshift.io/v1
kind: PtpConfig
metadata:
  name: example-ptpconfig
  namespace: openshift-ptp
spec:
  profile:
  - name: "profile1"
    interface: "enp5s0f0"
    ptp4lOpts: "-2 -s --summary_interval -4" 1
    phc2sysOpts: "-a -r -m -n 24 -N 8 -R 16" 2
    ptp4lConf: ""                            3
  ptpClockThreshold:                         4
    holdOverTimeout: 5
    maxOffsetThreshold: 100
    minOffsetThreshold: -100
    1
    Append --summary_interval -4 to use PTP fast events.
    2
    Required phc2sysOpts values. -m prints messages to stdout. The linuxptp-daemon DaemonSet parses the logs and generates Prometheus metrics.
    3
    Specify a string that contains the configuration to replace the default /etc/ptp4l.conf file. To use the default configuration, leave the field empty.
    4
    Optional. If the ptpClockThreshold stanza is not present, default values are used for the ptpClockThreshold fields. The stanza shows default ptpClockThreshold values. The ptpClockThreshold values configure how long after the PTP master clock is disconnected before PTP events are triggered. holdOverTimeout is the time value in seconds before the PTP clock event state changes to FREERUN when the PTP master clock is disconnected. The maxOffsetThreshold and minOffsetThreshold settings configure offset values in nanoseconds that compare against the values for CLOCK_REALTIME (phc2sys) or master offset (ptp4l). When the ptp4l or phc2sys offset value is outside this range, the PTP clock state is set to FREERUN. When the offset value is within this range, the PTP clock state is set to LOCKED.

11.10.5. Subscribing DU applications to PTP events REST API reference

Use the PTP event notifications REST API to subscribe a distributed unit (DU) application to the PTP events that are generated on the parent node.

Subscribe applications to PTP events by using the resource address /cluster/node/<node_name>/ptp, where <node_name> is the cluster node running the DU application.

Deploy your cloud-event-consumer DU application container and cloud-event-proxy sidecar container in a separate DU application pod. The cloud-event-consumer DU application subscribes to the cloud-event-proxy container in the application pod.

Use the following API endpoints to subscribe the cloud-event-consumer DU application to PTP events posted by the cloud-event-proxy container at http://localhost:8089/api/cloudNotifications/v1/ in the DU application pod:

  • /api/cloudNotifications/v1/subscriptions

    • POST: Creates a new subscription
    • GET: Retrieves a list of subscriptions

  • /api/cloudNotifications/v1/subscriptions/<subscription_id>

    • GET: Returns details for the specified subscription ID

  • api/cloudNotifications/v1/subscriptions/status/<subscription_id>

    • PUT: Creates a new status ping request for the specified subscription ID

  • /api/cloudNotifications/v1/health

    • GET: Returns the health status of cloudNotifications API
Note

9089 is the default port for the cloud-event-consumer container deployed in the application pod. You can configure a different port for your DU application as required.

11.10.5.1. api/cloudNotifications/v1/subscriptions

11.10.5.1.1. HTTP method

GET api/cloudNotifications/v1/subscriptions

11.10.5.1.1.1. Description

Returns a list of subscriptions. If subscriptions exist, a 200 OK status code is returned along with the list of subscriptions.

Example API response

[
 {
  "id": "75b1ad8f-c807-4c23-acf5-56f4b7ee3826",
  "endpointUri": "http://localhost:9089/event",
  "uriLocation": "http://localhost:8089/api/cloudNotifications/v1/subscriptions/75b1ad8f-c807-4c23-acf5-56f4b7ee3826",
  "resource": "/cluster/node/compute-1.example.com/ptp"
 }
]

11.10.5.1.2. HTTP method

POST api/cloudNotifications/v1/subscriptions

11.10.5.1.2.1. Description

Creates a new subscription. If a subscription is successfully created, or if it already exists, a 201 Created status code is returned.

Table 11.1. Query parameters
ParameterType

subscription

data

Example payload

{
  "uriLocation": "http://localhost:8089/api/cloudNotifications/v1/subscriptions",
  "resource": "/cluster/node/compute-1.example.com/ptp"
}

11.10.5.2. api/cloudNotifications/v1/subscriptions/<subscription_id>

11.10.5.2.1. HTTP method

GET api/cloudNotifications/v1/subscriptions/<subscription_id>

11.10.5.2.1.1. Description

Returns details for the subscription with ID <subscription_id>

Table 11.2. Query parameters
ParameterType

<subscription_id>

string

Example API response

{
  "id":"48210fb3-45be-4ce0-aa9b-41a0e58730ab",
  "endpointUri": "http://localhost:9089/event",
  "uriLocation":"http://localhost:8089/api/cloudNotifications/v1/subscriptions/48210fb3-45be-4ce0-aa9b-41a0e58730ab",
  "resource":"/cluster/node/compute-1.example.com/ptp"
}

11.10.5.3. api/cloudNotifications/v1/subscriptions/status/<subscription_id>

11.10.5.3.1. HTTP method

PUT api/cloudNotifications/v1/subscriptions/status/<subscription_id>

11.10.5.3.1.1. Description

Creates a new status ping request for subscription with ID <subscription_id>. If a subscription is present, the status request is successful and a 202 Accepted status code is returned.

Table 11.3. Query parameters
ParameterType

<subscription_id>

string

Example API response

{"status":"ping sent"}

11.10.5.4. api/cloudNotifications/v1/health/

11.10.5.4.1. HTTP method

GET api/cloudNotifications/v1/health/

11.10.5.4.1.1. Description

Returns the health status for the cloudNotifications REST API.

Example API response

OK

11.10.6. Monitoring PTP fast event metrics using the CLI

You can monitor fast events bus metrics directly from cloud-event-proxy containers using the oc CLI.

Note

PTP fast event notification metrics are also available in the OpenShift Container Platform web console.

Prerequisites

  • Install the OpenShift Container Platform CLI (oc).
  • Log in as a user with cluster-admin privileges.
  • Install and configure the PTP Operator.

Procedure

  1. Get the list of active linuxptp-daemon pods. 

    $ oc get pods -n openshift-ptp

    Example output

    NAME                    READY   STATUS    RESTARTS   AGE
linuxptp-daemon-2t78p   3/3     Running   0          8h
linuxptp-daemon-k8n88   3/3     Running   0          8h

  2. Access the metrics for the required cloud-event-proxy container by running the following command: 

    $ oc exec -it <linuxptp-daemon> -n openshift-ptp -c cloud-event-proxy -- curl 127.0.0.1:9091/metrics

    where:

    <linuxptp-daemon>

    Specifies the pod you want to query, for example, linuxptp-daemon-2t78p.

    Example output

    # HELP cne_amqp_events_published Metric to get number of events published by the transport
# TYPE cne_amqp_events_published gauge
cne_amqp_events_published{address="/cluster/node/compute-1.example.com/ptp/status",status="success"} 1041
# HELP cne_amqp_events_received Metric to get number of events received  by the transport
# TYPE cne_amqp_events_received gauge
cne_amqp_events_received{address="/cluster/node/compute-1.example.com/ptp",status="success"} 1019
# HELP cne_amqp_receiver Metric to get number of receiver created
# TYPE cne_amqp_receiver gauge
cne_amqp_receiver{address="/cluster/node/mock",status="active"} 1
cne_amqp_receiver{address="/cluster/node/compute-1.example.com/ptp",status="active"} 1
cne_amqp_receiver{address="/cluster/node/compute-1.example.com/redfish/event",status="active"}
...

11.10.7. Monitoring PTP fast event metrics in the web console

You can monitor PTP fast event metrics in the OpenShift Container Platform web console by using the pre-configured and self-updating Prometheus monitoring stack.

Prerequisites

  • Install the OpenShift Container Platform CLI oc.
  • Log in as a user with cluster-admin privileges.

Procedure

  1. Enter the following command to return the list of available PTP metrics from the cloud-event-proxy sidecar container: 

    $ oc exec -it <linuxptp_daemon_pod> -n openshift-ptp -c cloud-event-proxy -- curl 127.0.0.1:9091/metrics

    where:

    <linuxptp_daemon_pod>
    Specifies the pod you want to query, for example, linuxptp-daemon-2t78p.
  2. Copy the name of the PTP metric you want to query from the list of returned metrics, for example, cne_amqp_events_received.
  3. In the OpenShift Container Platform web console, click Observe Metrics.
  4. Paste the PTP metric into the Expression field, and click Run queries.

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