Precision Time Protocol - PTP
Cumulus Linux supports IEEE 1588-2008 Precision Timing Protocol (PTPv2), which defines the algorithm and method for synchronizing clocks of various devices across packet-based networks, including Ethernet switches and IP routers.
PTP is capable of sub-microsecond accuracy. The clocks are in a master-slave hierarchy, where the slaves synchronize to their masters, which can be slaves to their own masters. The best master clock (BMC) algorithm, which runs on every clock, creates and updates the hierarchy automatically. The grandmaster clock is the top-level master. To provide a high-degree of accuracy, a Global Positioning System (GPS) time source typically synchronizes the grandmaster clock.
In the following example:
- Boundary clock 2 receives time from Master 1 (the grandmaster) on a PTP slave port, sets its clock and passes the time down from the PTP master port to Boundary clock 1.
- Boundary clock 1 receives the time on a PTP slave port, sets its clock and passes the time down the hierarchy through the PTP master ports to the hosts that receive the time.
Cumulus Linux and PTP
PTP in Cumulus Linux uses the linuxptp package that includes the following programs:
ptp4lprovides the PTP protocol and state machinesphc2sysprovides PTP Hardware Clock and System Clock synchronizationtimemasterprovides System Clock and PTP synchronization
Cumulus Linux supports:
- PTP boundary clock mode only (the switch provides timing to downstream servers; it is a slave to a higher-level clock and a master to downstream clocks).
- UDPv4, UDPv6, and 802.3 encapsulation.
- Only a single PTP domain per network.
- PTP on layer 3 interfaces, layer 3 bonds, trunk ports, and switch ports belonging to a VLAN.
- Multicast, unicast, and mixed message mode.
- End-to-End delay mechanism only. Cumulus Linux does not support Peer-to-Peer.
- One-step and two-step clock timestamp mode.
- Hardware timestamping for PTP packets. This allows PTP to avoid inaccuracies caused by message transfer delays and improves the accuracy of time synchronization.
- On NVIDIA switches with Spectrum-2 and later, PTP is not supported on 1G interfaces.
- On Spectrum-4 switches, PTP is Beta.
- You cannot run both PTP and NTP on the switch.
- PTP supports the default VRF only.
Basic Configuration
Basic PTP configuration requires you:
- Enable PTP on the switch.
- Configure PTP on at least one interface; this can be a layer 3 routed port, switch port, or trunk port. You do not need to specify which is a master interface and which is a slave interface; the PTP Best Master Clock Algorithm (BMCA) determines the master and slave.
If you configure PTP with Linux commands, you must also enable PTP timestamping; see step 1 of the Linux procedure below. NVUE enables timestamping when you enable PTP on the switch.
The basic configuration shown below uses the default PTP settings:
- The clock mode is Boundary. This is the only clock mode that Cumulus Linux supports.
- The PTP clock domain is 0.
- PTP Priority1 and Priority2 are both 128.
- The DSCP is 46 for both general and event messages.
- The PTP interface transport mode is IPv4.
- Announce messages from any master are accepted.
- The PTP Interface Message Mode is multicast.
- The delay mechanism is End-to-End (E2E), where the slave measures the delay between itself and the master. The master and slave send delay request and delay response messages between each other to measure the delay.
- The clock timestamp mode is two-step.
To configure other settings, such as the PTP profile, domain, priority, and DSCP, the PTP interface transport mode and timers, and PTP monitoring, see the Optional Configuration sections below.
The NVUE nv set service ptp commands require an instance number (1 in the example command below) for management purposes.
When you enable the PTP service with the nv set service ptp <instance> enable on command, NVUE restarts the switchd service, which causes all network ports to reset in addition to resetting the switch hardware configuration.
cumulus@switch:~$ nv set service ptp 1 enable on
cumulus@switch:~$ nv set interface swp1 ip address 10.0.0.9/32
cumulus@switch:~$ nv set interface swp2 ip address 10.0.0.10/32
cumulus@switch:~$ nv set interface swp1 ptp enable on
cumulus@switch:~$ nv set interface swp2 ptp enable on
cumulus@switch:~$ nv config apply
The configuration writes to the /etc/ptp4l.conf file.
cumulus@switch:~$ nv set service ptp 1 enable on
cumulus@switch:~$ nv set bridge domain br_default
cumulus@switch:~$ nv set bridge domain br_default type vlan-aware
cumulus@switch:~$ nv set bridge domain br_default vlan 10-30
cumulus@switch:~$ nv set bridge domain br_default vlan 10 ptp enable on
cumulus@switch:~$ nv set interface vlan10 type svi
cumulus@switch:~$ nv set interface vlan10 ip address 10.1.10.2/24
cumulus@switch:~$ nv set interface vlan10 ptp enable on
cumulus@switch:~$ nv set interface swp1 bridge domain br_default
cumulus@switch:~$ nv set interface swp1 bridge domain br_default vlan 10
cumulus@switch:~$ nv set interface swp1 ptp enable on
cumulus@switch:~$ nv config apply
- You can configure only one address; either IPv4 or IPv6.
- For IPv6, set the trunk port transport mode to ipv6.
The configuration writes to the /etc/ptp4l.conf file.
cumulus@switch:~$ nv set service ptp 1 enable on
cumulus@switch:~$ nv set bridge domain br_default
cumulus@switch:~$ nv set bridge domain br_default type vlan-aware
cumulus@switch:~$ nv set bridge domain br_default vlan 10-30
cumulus@switch:~$ nv set bridge domain br_default vlan 10 ptp enable on
cumulus@switch:~$ nv set interface vlan10 type svi
cumulus@switch:~$ nv set interface vlan10 ip address 10.1.10.2/24
cumulus@switch:~$ nv set interface swp2 bridge domain br_default
cumulus@switch:~$ nv set interface swp2 bridge domain br_default access 10
cumulus@switch:~$ nv set interface swp2 ptp enable on
cumulus@switch:~$ nv config apply
- You can configure only one address; either IPv4 or IPv6.
- For IPv6, set the trunk port transport mode to ipv6.
The configuration writes to the /etc/ptp4l.conf file.
-
Edit the
/etc/cumulus/switchd.d/ptp.conffile to set theptp.timestampingparameter toTRUE:cumulus@switch:~$ sudo nano /etc/cumulus/switchd.d/ptp.conf ... ptp.timestamping TRUE ... -
Restart the
switchdservice:cumulus@switch:~$ sudo systemctl restart switchd.service
Restarting the switchd service causes all network ports to reset in addition to resetting the switch hardware configuration.
-
Enable and start the ptp4l and phc2sys services:
cumulus@switch:~$ sudo systemctl enable ptp4l.service phc2sys.service cumulus@switch:~$ sudo systemctl start ptp4l.service phc2sys.service -
Edit the
Default interface optionssection of the/etc/ptp4l.conffile to configure the interfaces on the switch that you want to use for PTP.cumulus@switch:~$ sudo nano /etc/ptp4l.conf ... [global] # # Default Data Set # slaveOnly 0 priority1 128 priority2 128 domainNumber 0 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 3 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 step_threshold 0.000002 first_step_threshold 0.000020 max_frequency 900000000 sanity_freq_limit 0 # # Default interface options # time_stamping software # Interfaces in which ptp should be enabled # these interfaces should be routed ports # if an interface does not have an ip address # the ptp4l will not work as expected. [swp1] udp_ttl 1 masterOnly 0 delay_mechanism E2E [swp2] udp_ttl 1 masterOnly 0 delay_mechanism E2EFor a trunk VLAN, add the VLAN configuration to the switch port stanza: set
l2_modetotrunk,vlan_intfto the VLAN interface, andsrc_ipto the IP address of the VLAN interface:[swp1] l2_mode trunk vlan_intf vlan10 src_ip 10.1.10.2 udp_ttl 1 masterOnly 0 delay_mechanism E2E network_transport UDPv4For a switch port VLAN, add the VLAN configuration to the switch port stanza: set
l2_modetoaccess,vlan_intfto the VLAN interface, andsrc_ipto the IP address of the VLAN interface:[swp2] l2_mode access vlan_intf vlan10 src_ip 10.1.10.2 udp_ttl 1 masterOnly 0 delay_mechanism E2E network_transport UDPv4 -
Restart the
ptp4lservice:cumulus@switch:~$ sudo systemctl restart ptp4l.service
Global Configuration
Cumulus Linux provides several ways to modify the default basic global configuration. You can:
- Use profiles.
- Modify the parameters directly with NVUE commands.
- Modify the Linux
/etc/ptp4l.conffile.
When a predefined profile is set, NVUE does not allow you to configure global parameters. Do not edit the Linux /etc/ptp4l.conf file to modify the global parameters when a predefined profile is in use. For information about profiles, see PTP Profiles.
Clock Domains
PTP domains allow different independent timing systems to be present in the same network without confusing each other. A PTP domain is a network or a portion of a network within which all the clocks synchronize. Every PTP message contains a domain number. A PTP instance works in only one domain and ignores messages that contain a different domain number. Cumulus Linux supports only one domain in the system.
You can specify multiple PTP clock domains. PTP isolates each domain from other domains so that each domain is a different PTP network. You can specify a number between 0 and 127.
The following example commands configure domain 3 when a profile is not set:
cumulus@switch:~$ nv set service ptp 1 domain 3
cumulus@switch:~$ nv config apply
Edit the Default Data Set section of the /etc/ptp4l.conf file to change the domainNumber setting, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 128
priority2 128
domainNumber 3
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
Clock Timestamp Mode
The Cumulus Linux switch provides the following clock timestamp modes:
- One-step, where PTP adds the precise time that the Sync packet egresses the port to the packet. There is no need for a follow up packet.
- Two-step, where PTP notes the precise time when the Sync packet egresses the port and sends it in a separate follow up message.
One-step mode significantly reduces the number of PTP messages. Two-step mode is the default configuration.
Cumulus Linux supports one-step mode on switches with the Spectrum-2 and Spectrum-3 ASIC.
The following example commands configure one-step mode when a profile is not set:
cumulus@switch:~$ nv set service ptp 1 two-step off
cumulus@switch:~$ nv config apply
To revert the clock timestamp mode to the default setting (two-step mode), run the nv set service ptp 1 two-step on command.
To set the clock timestamp mode for a custom profile based on IEEE1588, ITU 8275-1 or ITU 8275-2, run the nv set service ptp <instance-id> profile <profile-id> two-step command. For example, to set one-step mode for the custom profile called CUSTOM1, run the nv set service ptp 1 profile CUSTOM1 two-step off command.
Edit the Default Data Set section of the /etc/ptp4l.conf file to change the twoStepFlag setting to 0, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 254
priority2 254
domainNumber 3
twoStepFlag 0
dscp_event 43
dscp_general 43
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
To revert the clock timestamp mode to the default setting (two-step mode), change the twoStepFlag setting to 1.
PTP Priority
The BMC selects the PTP master according to the criteria in the following order:
- Priority 1
- Clock class
- Clock accuracy
- Clock variance
- Priority 2
- Port ID
Use the PTP priority to select the best master clock. You can set priority 1 and 2:
- Priority 1 overrides the clock class and quality selection criteria to select the best master clock.
- Priority 2 identifies primary and backup clocks among identical redundant Grandmasters.
The range for both priority1 and priority2 is between 0 and 255. The default priority is 128. For the boundary clock, use a number above 128. The lower priority applies first.
The following example commands set priority 1 and priority 2 to 200 when a profile is not set:
cumulus@switch:~$ nv set service ptp 1 priority1 200
cumulus@switch:~$ nv set service ptp 1 priority2 200
cumulus@switch:~$ nv config apply
Edit the Default Data Set section of the /etc/ptp4l.conf file to change the priority1 and, or priority2 setting, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 200
priority2 200
domainNumber 3
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
Local Priority
Use the local priority when you create a custom profile based on a Telecom profile (ITU 8275-1 or ITU 8275-2). Modify the local priority in a custom profile to set the local priority of the local clock. You can set a value between 0 and 255. The default priority is 128.
The following example command configures the local priority to 10 for the custom profile called CUSTOM1, based on ITU 8275-2:
cumulus@switch:~$ nv set service ptp 1 profile CUSTOM1 local-priority 10
cumulus@switch:~$ nv config apply
Edit the G.8275.defaultDS.localPriority option in the /etc/ptp4l.conf file. After you save the /etc/ptp4l.conf file, restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 128
priority2 128
domainNumber 28
twoStepFlag 1
dscp_event 46
dscp_general 46
network_transport L2
dataset_comparison G.8275.x
G.8275.defaultDS.localPriority 10
ptp_dst_mac 01:80:C2:00:00:0E
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
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.
cumulus@switch:~$ nv set service ptp 1 ip-dscp 22
cumulus@switch:~$ nv config apply
Edit the Default Data Set section of the /etc/ptp4l.conf file to change the dscp_event setting for PTP messages that trigger a timestamp read from the clock and the dscp_general setting for PTP messages that carry commands, responses, information, or timestamps.
After you save the /etc/ptp4l.conf file, restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 200
priority2 200
domainNumber 3
twoStepFlag 1
dscp_event 22
dscp_general 22
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
PTP Interface Configuration
Cumulus Linux provides several ways to modify the default basic interface configuration. You can:
- Use profiles
- Modify the parameters directly with NVUE commands
- Modify the Linux
/etc/ptp4l.confconfiguration file.
When a profile is in use, avoid configuring the following interface configuration parameters with NVUE or in the Linux configuration file so that the interface retains its profile settings.
Transport Mode
By default, Cumulus Linux encapsulates PTP messages in UDP IPV4 frames. To encapsulate PTP messages on an interface in UDP IPV6 frames:
cumulus@switch:~$ nv set interface swp1 ptp transport ipv6
cumulus@switch:~$ nv config apply
Edit the Default interface options section of the /etc/ptp4l.conf file to change the network_transport setting for the interface, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
# Default interface options
#
time_stamping hardware
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
[swp1]
udp_ttl 1
masterOnly 0
delay_mechanism E2E
network_transport UDPv6
[swp2]
udp_ttl 1
masterOnly 0
delay_mechanism E2E
network_transport UDPv6
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
Message Mode
Cumulus Linux supports the following PTP message modes:
- Multicast, where the ports subscribe to two multicast addresses, one for event messages with timestamps and the other for general messages without timestamps. The Sync message that the master sends is a multicast message; all slave ports receive this message because the slaves need the time from the master. The slave ports in turn generate a Delay Request to the master. This is a multicast message that the intended master for the message and other slave ports receive. Similarly, all slave ports in addition to the intended slave port receive the master’s Delay Response. The slave ports receiving the unintended Delay Requests and Responses need to drop the packets. This can affect network bandwidth if there are hundreds of slave ports.
- Mixed, where Sync and Announce messages are multicast messages but Delay Request and Response messages are unicast. This avoids the issue seen in multicast message mode where every slave port sees Delay Requests and Responses from every other slave port.
- Unicast, where you configure the port as a unicast client or server. See Unicast Mode.
Multicast mode is the default setting; when you enable PTP on an interface, the message mode is multicast.
To change the message mode to mixed on swp1:
cumulus@switch:~$ nv set interface swp1 ptp mixed-multicast-unicast on
cumulus@switch:~$ nv config apply
To change the message mode back to the default setting of multicast on swp1:
cumulus@switch:~$ nv set interface swp1 ptp mixed-multicast-unicast off
cumulus@switch:~$ nv config apply
Edit the Default interface options section of the /etc/ptp4l.conf file to add the hybrid_e2e 1 line under the interface, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
# Default interface options
#
time_stamping hardware
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
[swp1]
hybrid_e2e 1
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
To change the message mode back to the default setting of multicast, remove the hybrid_e2e line under the interface, then restart the ptp4l service.
PTP Interface Timers
You can set the following timers for PTP messages.
| Timer | Description |
|---|---|
announce-interval |
The average interval between successive Announce messages. Specify the value as a power of two in seconds. |
announce-timeout |
The number of announce intervals that have to occur without receiving an Announce message before a timeout occurs. Make sure that this value is longer than the announce-interval in your network. |
delay-req-interval |
The minimum average time interval allowed between successive Delay Required messages. |
sync-interval |
The interval between PTP synchronization messages on an interface. Specify the value as a power of two in seconds. |
- To set the timers with NVUE, run the
nv set interface <interface> ptp timers <timer> <value>command. - To set the timers with Linux commands, edit the
/etc/ptp4l.conffile and set the timers in theDefault interface optionssection.
The following example sets the announce interval between successive Announce messages on swp1 to -1.
cumulus@switch:~$ nv set interface swp1 ptp timers announce-interval -1
cumulus@switch:~$ nv config apply
The following example sets the mean sync-interval for multicast messages on swp1 to -5.
cumulus@switch:~$ nv set interface swp1 ptp timers sync-interval -5
cumulus@switch:~$ nv config apply
Edit the Default interface options section of the /etc/ptp4l.conf file:
- To set the announce interval between successive Announce messages on swp1 to -1, add
logAnnounceInterval -1under the interface stanza. - To set the mean sync-interval for multicast messages on swp1 to -5, add
logSyncInterval -5under the interface stanza.
After you edit the /etc/ptp4l.conf file, restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
# Default interface options
#
time_stamping hardware
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
[swp1]
logAnnounceInterval -1
logSyncInterval -5
udp_ttl 20
masterOnly 1
delay_mechanism E2E
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
Local Priority
Set the local priority on an interface for a profile that uses ITU 8275-1 or ITU 8275-2. You can set a value between 0 and 255. The default priority is 128.
The following example sets the local priority on swp1 to 10.
cumulus@switch:~$ nv set interface swp1 ptp local-priority 10
cumulus@switch:~$ nv config apply
Add the G.8275.portDS.localPriority option to the interface section of the /etc/ptp4l.conf file, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
[swp1]
udp_ttl 1
hybrid_e2e 1
masterOnly 0
delay_mechanism E2E
network_transport UDPv6
G.8275.portDS.localPriority 10
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
Optional PTP Interface Configuration
Forced Master Mode
By default, PTP ports are in auto mode, where the BMC algorithm determines the state of the port.
You can configure Forced Master mode on a PTP port so that it is always in a master state and the BMC algorithm does not run for this port. This port ignores any Announce messages it receives.
cumulus@switch:~$ nv set interface swp1 ptp forced-master on
cumulus@switch:~$ nv config apply
Edit the Default interface options section of the /etc/ptp4l.conf file to change the masterOnly setting for the interface, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
# Default interface options
#
time_stamping hardware
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
[swp1]
udp_ttl 1
masterOnly 1
delay_mechanism E2E
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
TTL for a PTP Message
To restrict the number of hops a PTP message can travel, set the TTL on the PTP interface. You can set a value between 1 and 255.
cumulus@switch:~$ nv set interface swp1 ptp ttl 20
cumulus@switch:~$ nv config apply
Edit the Default interface options section of the /etc/ptp4l.conf file to change the udp_ttl setting for the interface, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
# Default interface options
#
time_stamping hardware
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
[swp1]
udp_ttl 20
masterOnly 1
delay_mechanism E2E
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
Unicast Mode
Cumulus Linux supports unicast mode so that a unicast client can perform Unicast Discover and Negotiation with servers. Unlike the default multicast mode, where both the server(master) and client(slave) start sending out announce requests and discover each other, in unicast mode, the client starts by sending out requests for unicast transmission. The client sends this to every server address in its Unicast Master Table. The server responds with an accept or deny to the request.
Global Unicast Configuration
Unicast clients need a unicast master table for unicast negotiation; you must configure at least one unicast master table on the switch.
To configure unicast globally:
- Set the unicast table ID; a unique ID that identifies the unicast master table.
- Set the unicast master address. You can set more than one unicast master address, which can be an IPv4, IPv6, or MAC address.
- Optional: Set the unicast master query interval, which is the mean interval between requests for Announce messages. Specify this value as a power of two in seconds. You can specify a value between -3 and 4. The default value is -0 (2 power).
cumulus@switch:~$ nv set service ptp 1 unicast-master 1 address 10.10.10.1 cumulus@switch:~$ nv set service ptp 1 unicast-master 1 query-interval 4 cumulus@switch:~$ nv set interface swp1 ptp unicast-master-table-id 1 cumulus@switch:~$ nv config apply-
Add the following lines at the end of the
# Default interface optionssection of the/etc/ptp4l.conffile:cumulus@switch:~$ sudo nano /etc/ptp4l.conf ... # Default interface options ... [unicast_master_table] table_id 1 logQueryInterval 4 UDPv4 10.10.10.1 ... -
Restart the
ptp4lservice.cumulus@switch:~$ sudo systemctl restart ptp4l.service
-
Interface Unicast Configuration
For interface unicast configuration, in addition to enabling PTP on an interface, you also need to configure the PTP interface to be either a unicast client or a unicast server.
When configuring multiple PTP interfaces on the switch to be unicast clients, you must configure a unicast table ID on every interface set as a unicast client. Each client must have a different table ID.
To configure a PTP interface to be the unicast client:
cumulus@switch:~$ nv set interface swp1 ptp unicast-service-mode client
cumulus@switch:~$ nv config apply
-
Add the following lines at the end of the interface section of the
/etc/ptp4l.conffile:[unicast_master_table] table_id 3 logQueryInterval 0 UDPv4 100.100.100.1 [swp1] table_id 1 ... -
Restart the
ptp4lservice.cumulus@switch:~$ sudo systemctl restart ptp4l.service
To configure a PTP interface to be the unicast server:
cumulus@switch:~$ nv set interface swp1 ptp unicast-service-mode server
cumulus@switch:~$ nv config apply
-
Add the following lines at the end of the interface section of the
/etc/ptp4l.conffile:[swp1] ... unicast_listen 1 ... -
Restart the
ptp4lservice.cumulus@switch:~$ sudo systemctl restart ptp4l.service
To configure a unicast table ID:
cumulus@switch:~$ nv set interface swp1 ptp unicast-master-table-id 1
cumulus@switch:~$ nv config apply
-
Add the table ID at the end of the interface section of the
/etc/ptp4l.conffile:[swp1] ... table_id 1 -
Restart the
ptp4lservice.cumulus@switch:~$ sudo systemctl restart ptp4l.service
To show the unicast master table configuration on the switch, run the nv show service ptp <instance-id> unicast-master <table-id> command.
Optional Unicast Interface Configuration
You can set the unicast request duration for unicast clients, which is the service time in seconds requested by the unicast client during unicast negotiation. The default value is 300 seconds.
cumulus@switch:~$ nv set interface swp1 ptp unicast-request-duration 20
cumulus@switch:~$ nv config apply
-
Add the
unicast_request_durationparameter at the end of the interface section of the/etc/ptp4l.conffile:[swp1] ... table_id 1 unicast_request_duration 20 -
Restart the
ptp4lservice.cumulus@switch:~$ sudo systemctl restart ptp4l.service
PTP Profiles
PTP profiles are a standardized set of configurations and rules intended to meet the requirements of a specific application. Profiles define required, allowed, and restricted PTP options, network restrictions, and performance requirements.
Cumulus Linux supports the following predefined profiles:
| IEEE 1588 | ITU 8275-1 | ITU 8275-2 | |
|---|---|---|---|
| Application | Enterprise | Mobile Networks | Mobile Networks |
| Transport | Layer 2 and Layer 3 | Layer 2 | Layer 3 |
| Encapsulation | 802.3, UDPv4, or UDPv6 | 802.3 | UDPv4 or UDPv6 |
| Transmission | Unicast and Multicast | Multicast | Unicast |
| Supported Clock Types | Boundary Clock | Boundary Clock | Boundary Clock |
- You cannot modify the predefined profiles. If you want to set a parameter to a different value in a predefined profile, you need to create a custom profile. You can modify a custom profile within the range applicable to the profile type.
- You cannot set the current profile to a profile not yet created.
- You cannot set global PTP parameters in a profile currently in use.
- PTP profiles do not support VLANs or bonds.
- If you set a predefined or custom profile, do not change any global PTP settings, such as the DSCP or the clock domain.
- For better performance in a high scale network with PTP on multiple interfaces, configure a higher system policer rate with the
nv set system control-plane policer lldp-ptp burst <value>andnv set system control-plane policer lldp-ptp rate <value>commands. The switch uses the LLDP policer for PTP protocol packets. The default value for the LLDP policer is 2500. When you use the ITU 8275.1 profile with higher sync rates, use higher policer values.
Set a Predefined Profile
To set a predefined profile:
- To set the ITU 8275.1 profile, run the
nv set service ptp <instance-id> current-profile default-itu-8275-1command. - To set the ITU 8275.2 profile, run the
nv set service ptp <instance-id> current-profile default-itu-8275-2command.
The following example sets the profile to ITU 8275.1
cumulus@switch:~$ nv set service ptp 1 current-profile default-itu-8275-1
cumulus@switch:~$ nv config apply
To set the IEEE 1588 profile:
cumulus@switch:~$ nv set service ptp 1 current-profile default-1588
cumulus@switch:~$ nv config apply
To set the predefined ITU 8275.1 profile, edit the /etc/ptp4l.conf file and set the parameters shown below, then restart the ptp4l service:
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
...
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 128
priority2 128
domainNumber 24
twoStepFlag 1
dscp_event 46
dscp_general 46
dataset_comparison G.8275.x
G.8275.defaultDS.localPriority 128
ptp_dst_mac 01:80:C2:00:00:0E
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
To set the predefined ITU 8275.2 profile, edit the /etc/ptp4l.conf file and set the parameters shown below, then restart the ptp4l service:
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
...
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 128
priority2 128
domainNumber 24
twoStepFlag 1
dscp_event 46
dscp_general 46
network_transport UDPv4
dataset_comparison G.8275.x
G.8275.defaultDS.localPriority 128
hybrid_e2e 1
inhibit_multicast_service 1
unicast_listen 1
unicast_req_duration 60
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
To use the predefined IEEE 1588 profile, edit the /etc/ptp4l.conf file and set the parameters shown below, then restart the ptp4l service:
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 128
priority2 128
domainNumber 0
twoStepFlag 1
dscp_event 46
dscp_general 46
network_transport UDPv4
dataset_comparison ieee1588
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service
Create a Custom Profile
To create a custom profile:
- Create a profile name.
- Set the profile type on which to base the new profile (
itu-g-8275-1itu-g-8275-2, orieee-1588). - Update any of the profile settings you want to change (
announce-interval,delay-req-interval,priority1,sync-interval,announce-timeout,domain,priority2,transport,delay-mechanism,local-priority). - Set the custom profile to be the current profile.
The following example commands create a custom profile called CUSTOM1 based on the predefined profile ITU 8275-1. The commands set the domain to 28 and the announce-timeout to 3, then set CUSTOM1 to be the current profile:
cumulus@switch:~$ nv set service ptp 1 profile CUSTOM1
cumulus@switch:~$ nv set service ptp 1 profile CUSTOM1 profile-type itu-g-8275-1
cumulus@switch:~$ nv set service ptp 1 profile CUSTOM1 domain 28
cumulus@switch:~$ nv set service ptp 1 profile CUSTOM1 announce-timeout 3
cumulus@switch:~$ nv set service ptp 1 current-profile CUSTOM1
cumulus@switch:~$ nv config apply
The following example /etc/ptp4l.conf file creates a custom profile based on the predefined profile ITU 8275-1 and sets the domain to 28 and the announce-timeout to 3.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 128
priority2 128
domainNumber 28
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 5
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 3
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
step_threshold 0.000002
first_step_threshold 0.000020
max_frequency 900000000
sanity_freq_limit 0
#
# Default interface options
#
time_stamping software
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
[swp1]
udp_ttl 1
masterOnly 0
delay_mechanism E2E
[swp2]
udp_ttl 1
masterOnly 0
delay_mechanism E2E
cumulus@switch:~$ sudo systemctl restart ptp4l.service
To show the current PTP profile setting, run the nv show service ptp <ptp-instance> command:
cumulus@switch:~$ nv show service ptp 1
operational applied description
--------------------------- ----------- ------------------ --------------------------------------------------------------------
enable on on Turn the feature 'on' or 'off'. The default is 'off'.
current-profile default-itu-8275-1 Current PTP profile index
domain 24 0 Domain number of the current syntonization
ip-dscp 46 46 Sets the Diffserv code point for all PTP packets originated locally.
priority1 128 128 Priority1 attribute of the local clock
priority2 128 128 Priority2 attribute of the local clock
...
To show the settings for a profile, run the nv show service ptp <instance> profile <profile-name> command:
cumulus@switch:~$ nv show service ptp 1 profile CUSTOM1
operational applied
--------------------------- ----------- ------------------
enable on
current-profile default-itu-8275-1
domain 0
ip-dscp 46
logging-level info
priority1 128
priority2 128
[acceptable-master]
monitor
max-offset-threshold 50
max-timestamp-entries 100
max-violation-log-entries 4
max-violation-log-sets 3
min-offset-threshold -50
path-delay-threshold 200
violation-log-interval 1
Optional Acceptable Master Table
The acceptable master table option is a security feature that prevents a rogue player from pretending to be the grandmaster clock to take over the PTP network. To use this feature, you configure the clock IDs of known grandmaster clocks in the acceptable master table and set the acceptable master table option on a PTP port. The BMC algorithm checks if the grandmaster clock received in the Announce message is in this table before proceeding with the master selection. Cumulus Linux disables this option by default on PTP ports.
The following example command adds the grandmaster clock ID 24:8a:07:ff:fe:f4:16:06 to the acceptable master table and enables the PTP acceptable master table option for swp1:
cumulus@switch:~$ nv set service ptp 1 acceptable-master 24:8a:07:ff:fe:f4:16:06
cumulus@switch:~$ nv config apply
You can also configure an alternate priority 1 value for the Grandmaster:
cumulus@switch:~$ nv set service ptp 1 acceptable-master 24:8a:07:ff:fe:f4:16:06 alt-priority 2
To enable the PTP acceptable master table option for swp1:
cumulus@switch:~$ nv set interface swp1 ptp acceptable-master on
cumulus@switch:~$ nv config apply
Edit the Default interface options section of the /etc/ptp4l.conf file to add acceptable_master_clockIdentity 248a07.fffe.f41606.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
#
# Default interface options
#
time_stamping hardware
[acceptable_master_table]
maxTableSize 16
acceptable_master_clockIdentity 248a07.fffe.f41606
...
You can also configure an alternate priority 1 value for the Grandmaster.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
#
# Default interface options
#
time_stamping hardware
[acceptable_master_table]
maxTableSize 16
acceptable_master_clockIdentity 248a07.fffe.f41606 2
To enable the PTP acceptable master table option for swp1, add acceptable_master on under [swp1].
...
# Default interface options
#
time_stamping hardware
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
[swp1]
udp_ttl 20
masterOnly 1
delay_mechanism E2E
acceptable_master on
...
Restart the ptp4l service:
cumulus@switch:~$ sudo systemctl restart ptp4l.service
Optional Monitor Configuration
Cumulus Linux provides the following optional PTP monitoring configuration.
Configure Clock TimeStamp and Path Delay Thresholds
Cumulus Linux monitors clock timestamp and path delay against thresholds, and generates counters when PTP reaches the set thresholds. You can see the counters in the NVUE nv show command output and in log messages.
You can configure the following monitor settings:
| Command | Description |
|---|---|
nv set service ptp <instance> monitor min-offset-threshold |
Sets the minimum difference allowed between the master and slave time. You can set a value between -1000000000 and 0 nanoseconds. The default value is -50 nanoseconds. |
nv set service ptp <instance> monitor max-offset-threshold |
Sets the maximum difference allowed between the master and slave time. You can set a value between 0 and 1000000000 nanoseconds. The default value is 50 nanoseconds. |
nv set service ptp <instance> monitor path-delay-threshold |
Sets the mean time that PTP packets take to travel between the master and slave. You can set a value between 0 and 1000000000 nanoseconds. The default value is 200 nanoseconds. |
nv set service ptp <instance> monitor max-timestamp-entries |
Sets the maximum number of timestamp entries allowed. Cumulus Linux updates the timestamps continuously. You can specify a value between 100 and 200. The default value is 100 entries. |
The following example sets the minimum offset threshold to -1000, the maximum offset threshold to 1000, and the path delay threshold to 300:
cumulus@switch:~$ nv set service ptp 1 monitor min-offset-threshold -1000
cumulus@switch:~$ nv set service ptp 1 monitor max-offset-threshold 1000
cumulus@switch:~$ nv set service ptp 1 monitor path-delay-threshold 300
cumulus@switch:~$ nv config apply
You can configure the following monitor settings manually in the /etc/ptp4l.conf file. Be sure to run the sudo systemctl restart ptp4l.service to apply the settings.
| Parameter | Description |
|---|---|
offset_from_master_min_threshold |
Sets the minimum difference allowed between the master and slave time. You can set a value between -1000000000 and 0 nanoseconds. The default value is -50 nanoseconds. |
offset_from_master_max_threshold |
Sets the maximum difference allowed between the master and slave time. You can set a value between 0 and 1000000000 nanoseconds. The default value is 50 nanoseconds. |
mean_path_delay_threshold |
Sets the mean time that PTP packets take to travel between the master and slave. You can set a value between 0 and 1000000000 nanoseconds. The default value is 200 nanoseconds. |
The following example sets the minimum offset threshold to -1000, the maximum offset threshold to 1000, and the path delay threshold to 300:
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 128
priority2 128
domainNumber 0
twoStepFlag 1
dscp_event 46
dscp_general 46
offset_from_master_min_threshold -1000
offset_from_master_max_threshold 1000
mean_path_delay_threshold 300
...
Configure PTP Logging
A log set contains the log entries for clock timestamp and path delay violations at different times. You can set the number of entries to log and the interval between successive violation logs.
| Command | Description |
|---|---|
nv set service ptp 1 monitor max-violation-log-sets |
Sets the maximum number of log sets allowed. You can specify a value between 2 and 4. The default value is 3. |
nv set service ptp 1 monitor max-violation-log-entries |
Sets the maximum number of log entries allowed in a log set. You can specify a value between 4 and 8. The default value is 4. |
nv set service ptp 1 monitor violation-log-interval |
Sets the number of seconds to wait before logging back-to-back violations. You can specify a value between 0 and 60. The default value is 1. |
The following example sets the maximum number of log sets allowed to 4, the maximum number of log entries allowed to 6, and the violation log interval to 10:
cumulus@switch:~$ nv set service ptp 1 monitor max-violation-log-sets 4
cumulus@switch:~$ nv set service ptp 1 monitor max-violation-log-entries 6
cumulus@switch:~$ nv set service ptp 1 monitor violation-log-interval 10
cumulus@switch:~$ nv config apply
You can configure the following monitor settings manually in the /etc/ptp4l.conf file. Be sure to run the sudo systemctl restart ptp4l.service to apply the settings.
| Parameter | Description |
|---|---|
tsmonitor_num_log_sets |
Sets the maximum number of log sets allowed. You can specify a value between 2 and 4. The default value is 3. |
tsmonitor_num_log_entries |
Sets the maximum number of log entries allowed in a log set. You can specify a value between 4 and 8. The default value is 4. |
tsmonitor_log_wait_seconds |
Sets the number of seconds to wait before logging back-to-back violations. You can specify a value between 0 and 60. The default value is 1. |
The following example sets the maximum number of log sets allowed to 4, the maximum number of log entries allowed to 6, and the violation log interval to 10:
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 128
priority2 128
domainNumber 0
twoStepFlag 1
dscp_event 46
dscp_general 46
offset_from_master_min_threshold -50
offset_from_master_max_threshold 50
mean_path_delay_threshold 300
tsmonitor_num_ts 100
tsmonitor_num_log_sets 4
tsmonitor_num_log_entries 6
tsmonitor_log_wait_seconds 10
...
Show PTP Logs
PTP monitoring provides commands to show counters for violations as well as the timestamp log entries for a violation.
| Command | Description |
|---|---|
nv show service ptp <instance> monitor timestamp-log |
Shows the last 25 PTP timestamps. |
nv show service ptp <instance> monitor violations |
Shows the threshold violation count and the last time a violation of a specific type occurred. |
nv show service ptp 1 monitor violations log acceptable-master |
Shows logs with violations that occur when a PTP server not in the Acceptable Master table sends an Announce request. |
nv show service ptp 1 monitor violations log forced-master |
Shows logs with violations that occur when a forced master port gets a higher clock. |
nv show service ptp 1 monitor violations log max-offset |
Shows logs with violations that occur when the timestamp offset is higher than the max offset threshold. |
nv show service ptp 1 monitor violations log min-Offset |
Shows logs with violations that occur when the timestamp offset is lower than the minimum offset threshold. |
nv show service ptp 1 monitor violations log path-delay |
Shows logs with violations that occur when the mean path delay is higher than the path delay threshold. |
The following example shows the threshold violation count and the last time a minimum offset threshold violation occurred:
cumulus@switch:~$ nv show service ptp 1 monitor violations
operational applied
---------------- --------------------------- -------
last-max-offset
last-min-offset 2023-04-24T15:22:01.312295Z
last-path-delay
max-offset-count 0
min-offset-count 2
path-delay-count 0
Clear PTP Violation Logs
- To clear the maximum offset violation logs, run the
nv action clear service ptp <instance> monitor violations log max-offsetcommand. - To clear the minimum offset violation logs, run the
nv action clear service ptp <instance> monitor violations log min-offsetcommand. - To clear the path delay violation logs, run the
nv action clear service ptp <instance> monitor violations log path-delaycommand.
cumulus@leaf01:mgmt:~$ nv action clear service ptp 1 monitor violations log path-delay
Action succeeded
Delete PTP Configuration
To delete PTP configuration, delete the PTP master and slave interfaces. The following example commands delete the PTP interfaces swp1, swp2, and swp3.
cumulus@switch:~$ nv unset interface swp1 ptp
cumulus@switch:~$ nv unset interface swp2 ptp
cumulus@switch:~$ nv unset interface swp3 ptp
cumulus@switch:~$ nv config apply
Edit the /etc/ptp4l.conf file to remove the interfaces from the Default interface options section, then restart the ptp4l service.
cumulus@switch:~$ sudo nano /etc/ptp4l.conf
...
# Default interface options
#
time_stamping hardware
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
cumulus@switch:~$ sudo systemctl restart ptp4l.service
To disable PTP on the switch and stop the ptp4l and phc2sys processes:
cumulus@switch:~$ nv set service ptp 1 enable off
cumulus@switch:~$ nv config apply
cumulus@switch:~$ sudo systemctl stop ptp4l.service phc2sys.service
cumulus@switch:~$ sudo systemctl disable ptp4l.service phc2sys.service
Troubleshooting
Show PTP Configuration
To show a summary of the PTP configuration on the switch, run the nv show service ptp <instance> command:
cumulus@switch:~$ nv show service ptp 1
operational applied
--------------------------- ----------- ------------------
enable on on
current-profile default-itu-8275-2
domain 0
ip-dscp 46
logging-level info
priority1 128
priority2 128
[acceptable-master]
monitor
max-offset-threshold 50
max-timestamp-entries 100
max-violation-log-entries 4
max-violation-log-sets 2
min-offset-threshold -50
path-delay-threshold 200
violation-log-interval 1
[profile] abc
[profile] default-1588
[profile] default-itu-8275-1
[profile] default-itu-8275-2
[unicast-master] 1
[unicast-master] 2
[unicast-master] 3
[unicast-master] 4
...
You can drill down with the following nv show service ptp <instance> commands:
nv show service ptp <instance> acceptable-mastershows acceptable master configuration.nv show service ptp <instance> clock-qualityshows the clock quality status.nv show service ptp <instance> currentshows the local states learned during PTP message exchange.nv show service ptp <instance> domainshows the domain configuration.nv show service ptp <instance> ip-dscpshows PTP DSCP configuration.nv show service ptp <instance> monitorshows PTP monitor configuration.nv show service ptp <instance> profileshows PTP profile configuration.nv show service ptp <instance> parentshows the local states learned during PTP message exchange.nv show service ptp <instance> priority1shows PTP priority1 configuration.nv show service ptp <instance> priority2shows PTP priority2 configuration.nv show service ptp <instance> statusshows the status of all PTP interfaces.nv show service ptp <instance> time-propertiesshows the clock time attributes.nv show service ptp <instance> unicast-mastershows the unicast master configuration.
Show PTP Interface Configuration
To check configuration for a PTP interface, run the nv show interface <interface> ptp command.
cumulus@switch:~$ nv show interface swp1 ptp
operational applied description
------------------------- ----------- ---------- ----------------------------------------------------------------------
enable on Turn the feature 'on' or 'off'. The default is 'off'.
acceptable-master off Determines if acceptable master check is enabled for this interface.
delay-mechanism end-to-end end-to-end Mode in which PTP message is transmitted.
forced-master off off Configures PTP interfaces to forced master state.
instance 1 PTP instance number.
mixed-multicast-unicast off Enables Multicast for Announce, Sync and Followup and Unicast for D...
transport ipv4 ipv4 Transport method for the PTP messages.
ttl 1 1 Maximum number of hops the PTP messages can make before it gets dro...
unicast-request-duration 300 The service time in seconds to be requested during discovery.
timers
announce-interval 0 0 Mean time interval between successive Announce messages. It's spec...
announce-timeout 3 3 The number of announceIntervals that have to pass without receipt o...
delay-req-interval -3 -3 The minimum permitted mean time interval between successive Delay R...
sync-interval -3 -3 The mean SyncInterval for multicast messages. It's specified as a...
peer-mean-path-delay 0 An estimate of the current one-way propagation delay on the link wh...
port-state master State of the port
protocol-version 2 The PTP version in use on the port
Show PTP Counters
To show all PTP counters, run the nv show service ptp <instance> counters command:
cumulus@switch:~$ nv show service ptp 1 counters
Packet Type Received Transmitted
--------------------- ------------ ------------
Port swp4
Announce 0 10370
Sync 0 20731
Follow-up 0 20731
Delay Request 0 0
Delay Response 0 0
Peer Delay Request 0 0
Peer Delay Response 0 0
Management 0 0
Signaling 0 0
To show PTP counters for an interface, run the nv show interface <interface> counters ptp command.
To clear PTP counters for an interface, run the nv action clear interface <interface> counters ptp command:
cumulus@switch:~$ nv action clear interface swp1 counters ptp
Action succeeded
Show the Status of All PTP Interfaces
To show the status of all PTP interfaces, run the nv show service ptp <instance> status command.
The command output shows the PTP enabled ports, the PTP port mode (unicast or multicast), the state of the port based on BMCA, the unicast state, and identifies the server address to which the client connects.
cumulus@switch:~$ nv show service ptp 1 status
Port Mode State Ustate Server
----- ----- ------- ------------------------------- -------
swp9 Ucast SLAVE Sync and Delay Granted (H_SYDY) 9.9.9.2
swp10 Ucast PASSIVE Initial State (WAIT)
swp11 Ucast PASSIVE Initial State (WAIT)
swp12 Ucast PASSIVE Initial State (WAIT)
Show the List of NVUE PTP Commands
- To see a full list of NVUE show commands for PTP, run the
nv list-commands service ptpcommand. - To show a full list of show commands for a PTP interface, run the
nv list-commands | grep 'nv show interface <interface-id> ptp'command.
cumulus@switch:~$ nv list-commands service ptp
nv show service ptp
nv show service ptp <instance-id>
nv show service ptp <instance-id> status
nv show service ptp <instance-id> domain
nv show service ptp <instance-id> priority1
nv show service ptp <instance-id> priority2
nv show service ptp <instance-id> ip-dscp
nv show service ptp <instance-id> acceptable-master
...
cumulus@switch:~$ nv list-commands | grep 'nv show interface <interface-id> ptp'
...
nv show interface <interface-id> ptp
nv show interface <interface-id> ptp timers
nv show interface <interface-id> ptp shaper
...
Example Configuration
In the following example, the boundary clock on the switch receives time from Master 1 (the grandmaster) on PTP slave port swp1, sets its clock and passes the time down through PTP master ports swp2, swp3, and swp4 to the hosts that receive the time.
The following example configuration assumes that you have already configured the layer 3 routed interfaces (swp1, swp2, swp3, and swp4) you want to use for PTP.
cumulus@switch:~$ nv set service ptp 1 enable on
cumulus@switch:~$ nv set service ptp 1 priority2 254
cumulus@switch:~$ nv set service ptp 1 priority1 254
cumulus@switch:~$ nv set service ptp 1 domain 3
cumulus@switch:~$ nv set interface swp1 ptp enable on
cumulus@switch:~$ nv set interface swp2 ptp enable on
cumulus@switch:~$ nv set interface swp3 ptp enable on
cumulus@switch:~$ nv set interface swp4 ptp enable on
cumulus@switch:~$ nv config apply
cumulus@switch:~$ sudo cat /etc/nvue.d/startup.yaml
- set:
interface:
lo:
ip:
address:
10.10.10.1/32: {}
type: loopback
swp1:
ptp:
enable: on
type: swp
swp2:
ptp:
enable: on
type: swp
swp3:
ptp:
enable: on
type: swp
swp4:
ptp:
enable: on
type: swp
service:
ptp:
'1':
domain: 3
enable: on
priority1: 254
priority2: 254
cumulus@switch:~$ sudo cat /etc/ptp4l.conf
...
[global]
#
# Default Data Set
#
slaveOnly 0
priority1 254
priority2 254
domainNumber 3
twoStepFlag 1
dscp_event 46
dscp_general 46
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
step_threshold 0.000002
first_step_threshold 0.000020
max_frequency 900000000
sanity_freq_limit 0
#
# Default interface options
#
time_stamping software
# Interfaces in which ptp should be enabled
# these interfaces should be routed ports
# if an interface does not have an ip address
# the ptp4l will not work as expected.
[swp1]
udp_ttl 1
masterOnly 0
delay_mechanism E2E
network_transport UDPv4
[swp2]
udp_ttl 1
masterOnly 0
delay_mechanism E2E
network_transport UDPv4
[swp3]
udp_ttl 1
masterOnly 0
delay_mechanism E2E
network_transport UDPv4
[swp4]
udp_ttl 1
masterOnly 0
delay_mechanism E2E
network_transport UDPv4
Considerations
PTP Traffic Shaping
To improve performance on the NVIDIA Spectrum 1 switch for PTP-enabled ports with speeds lower than 100G, you can enable a pre-defined traffic shaping profile. For example, if you see that the PTP timing offset varies widely and does not stabilize, enable PTP shaping on all PTP enabled ports to reduce the bandwidth on the ports slightly and improve timing stabilization.
-
Switches with Spectrum-2 and later do not support PTP shaping.
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Bonds do not support PTP shaping.
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You cannot configure QoS traffic shaping and PTP traffic shaping on the same ports.
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You must configure a strict priority for PTP traffic; for example:
cumulus@switch:~$ nv set qos egress-scheduler default-global traffic-class 0-5,7 mode dwrr cumulus@switch:~$ nv set qos egress-scheduler default-global traffic-class 0-5,7 bw-percent 12 cumulus@switch:~$ nv set qos egress-scheduler default-global traffic-class 6 mode strict
For each PTP-enabled port on which you want to set traffic shaping, run the nv set interface <interface> ptp shaper enable on command.
cumulus@switch:~$ nv set interface swp1 ptp shaper enable on
cumulus@switch:~$ nv set interface swp2 ptp shaper enable on
cumulus@switch:~$ nv config apply
To see the PTP shaping setting for an interface, run the nv show interface <interface> ptp shaper command:
cumulus@switch:~$ nv show interface swp1 ptp shaper
operational applied
------ ----------- -------
enable on
In the /etc/cumulus/switchd.d/ptp_shaper.conf file, set the following parameters for the interfaces to which you want to apply traffic shaping and enable the traffic shaper. You must reload switchd for the changes to take effect.
cumulus@switch:~$ sudo nano /etc/cumulus/switchd.d/ptp_shaper.conf
## Per-port configuration for PTP shaper
ptp_shaper.port_group_list = [enable-group]
ptp_shaper.enable-group.port_set = swp1,swp2
ptp_shaper.enable-group.ptp_shaper_enable = true
cumulus@switch:~$ sudo systemctl reload switchd.service
Spanning Tree and PTP
PTP frames are affected by STP filtering; events, such as an STP topology change (where ports temporarily go into the blocking state), can cause interruptions to PTP communications.
If you configure PTP on bridge ports, NVIDIA recommends that the bridge ports are spanning tree edge ports or in a bridge domain where spanning tree is disabled.