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:

  • ptp4l provides the PTP protocol and state machines
  • phc2sys provides PTP Hardware Clock and System Clock synchronization
  • timemaster provides System Clock and PTP synchronization
  • monitor provides monitoring

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).
  • Both IPv4 and IPv6 UDP PTP encapsulation. Cumulus Linux does not support 802.3 encapsulation.
  • Only a single PTP domain per network.
  • PTP on layer 3 interfaces, trunk ports, and switch ports belonging to a VLAN. Cumulus Linux does not support PTP on bonds.
  • Multicast and mixed message mode but not unicast only message mode.
  • End-to-End delay mechanism (not Peer-to-Peer).
  • Two-step clock correction mode, where PTP notes time when the packet goes out of the port and sends the time in a separate (follow-up) message. Cumulus Linux does not support one-step mode.
  • Hardware time stamping for PTP packets. This allows PTP to avoid inaccuracies caused by message transfer delays and improves the accuracy of time synchronization.

You cannot run both PTP and NTP on the switch. By default, PTP is enabled in the default VRF and on any new VRFs you create. You can disable PTP on a VRF to isolate PTP traffic.

Basic Configuration

Basic PTP configuration requires you:

  • Enable PTP on the switch to start the ptp4l and phc2sys processes.
  • Configure the interfaces on the switch that you want to use for PTP. Each interface must be a layer 3 routed interface with an IP address. 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.

The basic configuration shown below uses the default PTP settings:

To configure optional settings, such as the PTP domain, priority, transport mode, DSCP, and timers, see Optional Configuration below.

You can configure PTP with NVUE or by manually editing /etc/cumulus/switchd.conf file. You cannot configure PTP with NCLU.

The NVUE nv set service PTP commands require an instance number (1 in the example command below) for management purposes.

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.

  1. 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
    
  2. Edit the Default interface options section of the /etc/ptp4l.conf file 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              43
dscp_general            43

offset_from_master_min_threshold   -50
offset_from_master_max_threshold   50
mean_path_delay_threshold          200

#
# 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           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     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              0
delay_mechanism         E2E
network_transport       UDPv4

[swp2]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              0
delay_mechanism         E2E
network_transport       UDPv4
  1. Restart the ptp4l service:

    cumulus@switch:~$ sudo systemctl restart ptp4l.service
    

Optional Configuration

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.

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:

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               254
priority2               254
domainNumber            3
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service

PTP Priority

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:

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               254
priority2               254
domainNumber            3
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service

DSCP

You can configure the DiffServ code point (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               254
priority2               254
domainNumber            3

twoStepFlag             1
dscp_event              22
dscp_general            22
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service

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]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              0
delay_mechanism         E2E
network_transport       UDPv6

[swp2]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              0
delay_mechanism         E2E
network_transport       UDPv6
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service

Forced Master

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]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              1
delay_mechanism         E2E
network_transport       UDPv4
...
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 master’s time. The slave ports in turn generate a Delay Request to the master. This is a multicast message that the master for which the message is intended 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, especially 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.

    Mixed mode is an early access feature in Cumulus Linux.

Multicast mode is the default setting. To set the message mode to mixed on an interface:

NVUE commands are not supported.

Edit the Default interface options section of the /etc/ptp4l.conf file to change the Hybrid_e2e setting to 1 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]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 20
masterOnly              1
delay_mechanism         E2E
network_transport       UDPv4
Hybrid_e2e              1
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service

TTL for a PTP Message

TTL for a PTP message is an early access feature in Cumulus Linux.

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]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 20
masterOnly              1
delay_mechanism         E2E
network_transport       UDPv4
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service

Acceptable Master Table

The acceptable master table option is a security feature that prevents a rogue player from pretending to be the Grandmaster to take over the PTP network. To use this feature, you configure the clock IDs of known Grandmasters in the acceptable master table and set the acceptable master table option on a PTP port. The BMC algorithm checks if the Grandmaster received on the Announce message is in this table before proceeding with the master selection. This option is disabled 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 enable 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]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 20
masterOnly              1
delay_mechanism         E2E
network_transport       UDPv4
acceptable_master       on
...

Restart the ptp4l service:

cumulus@switch:~$ sudo systemctl restart ptp4l.service

PTP Timers

You can set the following timers for PTP messages.

TimerDescription
announce-intervalThe average interval between successive Announce messages. Specify the value as a power of two in seconds.
announce-timeoutThe 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-intervalThe minimum average time interval allowed between successive Delay Required messages.
sync-intervalThe 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.conf file and set the timers in the Default interface options section.

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, change the logAnnounceInterval setting for the interface to -1.
  • To set the mean sync-interval for multicast messages on swp1 to -5, change the logSyncInterval setting for the interface to -5.

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
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 20
masterOnly              1
delay_mechanism         E2E
network_transport       UDPv4
...
cumulus@switch:~$ sudo systemctl restart ptp4l.service

PTP on a VRF

By default, PTP is enabled on the default VRF and on any VRFs you create. You can isolate traffic to a specific VRF by disabling PTP on any other VRFs.

PTP in a VRF other than the default is an early access feature in Cumulus Linux.

cumulus@switch:~$ nv set vrf RED ptp enable off
cumulus@switch:~$ nv config apply
Linux commands are not supported.

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

NVUE provides several show commands for PTP. You can view the current PTP configuration, monitor violations, and see time attributes of the clock. For example, 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   description
----------------------  -----------  --------  ----------------------------------------------------------------------
enable                  off          on        Turn the feature 'on' or 'off'.  The default is 'off'.
clock-mode                           boundary  Clock mode
domain                               3         Domain number of the current syntonization
ipv4-dscp                            43        Sets the Diffserv code point for all PTP packets originated locally.
message-mode                         mixed     Mode in which PTP delay message is transmitted.
priority1                            254       Priority1 attribute of the local clock
priority2                            254       Priority2 attribute of the local clock
two-step                             off       Determines if the Clock is a 2 step clock
monitor
  max-offset-threshold               200       Maximum offset threshold in nano seconds
  min-offset-threshold               -200      Minimum offset threshold in nano seconds
  path-delay-threshold               1         Path delay threshold in nano seconds
...

To see the list of NVUE show commands for PTP, run nv list-commands service ptp:

cumulus@switch:~$ nv list-commands service ptp
nv show service ptp
nv show service ptp <instance-id>
nv show service ptp <instance-id> acceptable-master
nv show service ptp <instance-id> acceptable-master <clock-id>
nv show service ptp <instance-id> monitor
nv show service ptp <instance-id> monitor violations
nv show service ptp <instance-id> monitor violations forced-master
nv show service ptp <instance-id> monitor violations forced-master <clock-id>
nv show service ptp <instance-id> monitor violations acceptable-master
nv show service ptp <instance-id> monitor violations acceptable-master <clock-id>
nv show service ptp <instance-id> current
nv show service ptp <instance-id> clock-quality
nv show service ptp <instance-id> parent
nv show service ptp <instance-id> parent grandmaster-clock-quality
...

To view PTP status information, including the delta in nanoseconds from the master clock:

cumulus@switch:~$ sudo pmc -u -b 0 'GET TIME_STATUS_NP'
sending: GET TIME_STATUS_NP
    7cfe90.fffe.f56dfc-0 seq 0 RESPONSE MANAGEMENT TIME_STATUS_NP
        master_offset              12610
        ingress_time               1525717806521177336
        cumulativeScaledRateOffset +0.000000000
        scaledLastGmPhaseChange    0
        gmTimeBaseIndicator        0
        lastGmPhaseChange          0x0000'0000000000000000.0000
        gmPresent                  true
        gmIdentity                 000200.fffe.000005
    000200.fffe.000005-1 seq 0 RESPONSE MANAGEMENT TIME_STATUS_NP
        master_offset              0
        ingress_time               0
        cumulativeScaledRateOffset +0.000000000
        scaledLastGmPhaseChange    0
        gmTimeBaseIndicator        0
        lastGmPhaseChange          0x0000'0000000000000000.0000
        gmPresent                  false
        gmIdentity                 000200.fffe.000005
    000200.fffe.000006-1 seq 0 RESPONSE MANAGEMENT TIME_STATUS_NP
        master_offset              5544033534
        ingress_time               1525717812106811842
        cumulativeScaledRateOffset +0.000000000
        scaledLastGmPhaseChange    0
        gmTimeBaseIndicator        0
        lastGmPhaseChange          0x0000'0000000000000000.0000
        gmPresent                  true
        gmIdentity                 000200.fffe.000005

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:
        type: swp
        service:
          ptp:
            enable: on
      swp2:
        type: swp
        service:
          ptp:
            enable: on
      swp3:
        type: swp
        service:
          ptp:
            enable: on
      swp4:
        type: swp
        service:
          ptp:
            enable: on
    service:
      ptp:
        '1':
          enable: on
          priority1: 254
          priority2: 254
          domain: 3
cumulus@switch:~$ sudo cat /etc/ptp4l.conf
...
[global]
#
# Default Data Set
#
slaveOnly               0
priority1               254
priority2               254
domainNumber            3

clock_type              BC

twoStepFlag             1
dscp_event              43
dscp_general            43

offset_from_master_min_threshold   -200
offset_from_master_max_threshold   200
mean_path_delay_threshold          1

#
# Run time options
#
logging_level           6
path_trace_enabled      0
use_syslog              1
verbose                 0
summary_interval        0

#
# 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     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              0
delay_mechanism         E2E
network_transport       UDPv4

[swp2]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              0
delay_mechanism         E2E
network_transport       UDPv4

[swp3]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              0
delay_mechanism         E2E
network_transport       UDPv4

[swp4]
logAnnounceInterval     0
logSyncInterval         -3
logMinDelayReqInterval  -3
announceReceiptTimeout  3
udp_ttl                 1
masterOnly              0
delay_mechanism         E2E
network_transport       UDPv4