Ubuntu Manpage: ptp4l - PTP Boundary/Ordinary/Transparent Clock

Provided by: linuxptp_4.0-1ubuntu1_amd64

NAME

       ptp4l - PTP Boundary/Ordinary/Transparent Clock

SYNOPSIS

       ptp4l [ -AEP246HSLmqsv ] [ -f config ] [ -p phc-device ] [ -l print-level ] [ -i interface
       ] [ long-options ] ...

DESCRIPTION

       ptp4l is an implementation of the Precision Time Protocol (PTP) according to IEEE standard
       1588  for  Linux.  It implements Boundary Clock (BC), Ordinary Clock (OC), and Transparent
       Clock (TC).

OPTIONS

-A Select the delay mechanism automatically. Start with E2E and switch to P2P when a
peer delay request is received.

-E Select the delay request-response (E2E) mechanism. This is the default mechanism.
All clocks on single PTP communication path must use the same mechanism. A warning
will be printed when a peer delay request is received on port using the E2E
mechanism.

-P Select the peer delay (P2P) mechanism. A warning will be printed when a delay
request is received on port using the P2P mechanism.

-2 Select the IEEE 802.3 network transport.

-4 Select the UDP IPv4 network transport. This is the default transport.

-6 Select the UDP IPv6 network transport.

-H Select the hardware time stamping. All ports specified by the -i option and in the
configuration file must be attached to the same PTP hardware clock (PHC). This is
the default time stamping.

-S Select the software time stamping.

-L Select the legacy hardware time stamping.

-f config
Read configuration from the specified file. No configuration file is read by
default.

-i interface
Specify a PTP port, it may be used multiple times. At least one port must be
specified by this option or in the configuration file.

-p phc-device
(This option is deprecated.) Before Linux kernel v3.5 there was no way to discover
the PHC device associated with a network interface. This option specifies the PHC
device (e.g. /dev/ptp0) to be used when running on legacy kernels.

-s Enable the clientOnly mode.

-l print-level
Set the maximum syslog level of messages which should be printed or sent to the
system logger. The default is 6 (LOG_INFO).

-m Print messages to the standard output.

-q Don't send messages to the system logger.

-v Prints the software version and exits.

-h Display a help message.

LONG OPTIONS

       Each and every configuration file option (see below) may also appear  as  a  "long"  style
       command  line  argument.   For  example,  the clientOnly option may be set using either of
       these two forms.

              --clientOnly 1   --clientOnly=1

       Option values given on the command line override values  in  the  global  section  of  the
       configuration file.

CONFIGURATION FILE

       The  configuration  file  is  divided  into  sections.  Each  section  starts  with a line
       containing its name enclosed in brackets and it follows with settings.   Each  setting  is
       placed  on  a separate line, it contains the name of the option and the value separated by
       whitespace characters. Empty lines and lines starting with # are ignored.

       There are three different section types.

       1.     The global section (indicated as [global]) sets the program options, clock  options
              and  default  port  options.  Other  sections  are  port specific sections and they
              override the default port options.

       2.     Port sections give the name of the configured port (e.g.  [eth0]).  Ports specified
              in  the  configuration  file  don't need to be specified by the -i option. An empty
              port section can be used to replace the command line option.

       3.     Tables for configuring unicast discovery begin with [unicast_master_table].

              See UNICAST DISCOVERY OPTIONS, below.

PORT OPTIONS

announceReceiptTimeout
The number of missed Announce messages before the last Announce messages expires.
The default is 3.

boundary_clock_jbod
When running as a boundary clock (that is, when more than one network interface is
configured), ptp4l performs a sanity check to make sure that all of the ports share
the same hardware clock device. This option allows ptp4l to work as a boundary
clock using "just a bunch of devices" that are not synchronized to each other. For
this mode, the collection of clocks must be synchronized by an external program,
for example phc2sys(8) in "automatic" mode. The default is 0 (disabled).

delayAsymmetry
The time difference in nanoseconds of the transmit and receive paths. This value
should be positive when the server-to-client propagation time is longer and
negative when the client-to-server time is longer. The default is 0 nanoseconds.

delay_filter
Select the algorithm used to filter the measured delay and peer delay. Possible
values are moving_average and moving_median. The default is moving_median.

delay_filter_length
The length of the delay filter in samples. The default is 10.

delay_mechanism
Select the delay mechanism. Possible values are E2E, P2P, NONE and Auto. The
default is E2E.

delay_response_timeout
The number of delay response messages that may go missing before triggering a
synchronization fault. Setting this option to zero will disable the delay response
timeout. The default is 0 or disabled.

egressLatency
Specifies the difference in nanoseconds between the actual transmission time at the
reference plane and the reported transmit time stamp. This value will be added to
egress time stamps obtained from the hardware. The default is 0.

fault_badpeernet_interval
The time in seconds between the detection of a peer network misconfiguration and
the fault being reset. The port is disabled for the duration of the interval. The
value is in seconds and the special key word ASAP will let the fault be reset
immediately. The default is 16 seconds.

fault_reset_interval
The time in seconds between the detection of a port's fault and the fault being
reset. This value is expressed as a power of two. Setting this value to -128 or to
the special key word "ASAP" will let the fault be reset immediately. The default
is 4 (16 seconds).

follow_up_info
Include the 802.1AS data in the Follow_Up messages if enabled. The default is 0
(disabled).

G.8275.portDS.localPriority
The Telecom Profiles (ITU-T G.8275.1 and G.8275.2) specify an alternate Best Master
Clock Algorithm (BMCA) with a unique data set comparison algorithm. The value of
this option is associated with Announce messages arriving on a particular port and
is used as a tie breaker whenever clockClass, clockAccuracy,
offsetScaledLogVariance, and priority2 are equal. This option is only used when
"dataset_comparison" is set to "G.8275.x". The default value is 128.

Warning: the BMCA is guaranteed to produce a spanning tree (that is, a timing
network without loops) only when using the default values of
G.8275.defaultDS.localPriority and G.8275.portDS.localPriority. Careful network
engineering is needed when using non-default values.

hybrid_e2e
Enables the "hybrid" delay mechanism from the draft Enterprise Profile. When
enabled, ports in the client state send their delay request messages to the unicast
address taken from the server's announce message. Ports in the server state will
reply to unicast delay requests using unicast delay responses. This option has no
effect if the delay_mechanism is set to P2P. The default is 0 (disabled).

ignore_transport_specific
By default, incoming messages are dropped if their transportSpecific field does not
match the configured value. However, many of transports specified in the 1588
standard mandate ignoring this field. Moreover, some equipment is known to set the
reserved bits. Configuring this option as 1 causes this field to be ignored
completely on receive. The default is 0.

ingressLatency
Specifies the difference in nanoseconds between the reported receive time stamp and
the actual reception time at reference plane. This value will be subtracted from
ingress time stamps obtained from the hardware. The default is 0.

inhibit_delay_req
Don't send any delay requests. This will need the asCapable config option to be set
to 'true'. This is useful when running as a designated server who does not need to
calculate offset from client. The default is 0 (disabled).

inhibit_multicast_service
Some unicast mode profiles insist that no multicast message are ever transmitted.
Setting this option inhibits multicast transmission. The default is 0 (mutlicast
enabled).

logAnnounceInterval
The mean time interval between Announce messages. A shorter interval makes ptp4l
react faster to the changes in the client/server hierarchy. The interval should be
the same in the whole domain. It's specified as a power of two in seconds. The
default is 1 (2 seconds).

logMinDelayReqInterval
The minimum permitted mean time interval between Delay_Req messages. A shorter
interval makes ptp4l react faster to the changes in the path delay. It's specified
as a power of two in seconds. The default is 0 (1 second).

logMinPdelayReqInterval
The minimum permitted mean time interval between Pdelay_Req messages. It's
specified as a power of two in seconds. The default is 0 (1 second).

logSyncInterval
The mean time interval between Sync messages. A shorter interval may improve
accuracy of the local clock. It's specified as a power of two in seconds. The
default is 0 (1 second).

masterOnly
This option is deprecated and will be removed in a future release. Use
"serverOnly" instead.

min_neighbor_prop_delay
Lower limit for peer delay in nanoseconds. If the estimated peer delay is smaller
than this value the port is marked as not 802.1AS capable.

neighborPropDelayThresh
Upper limit for peer delay in nanoseconds. If the estimated peer delay is greater
than this value the port is marked as not 802.1AS capable.

network_transport
Select the network transport. Possible values are UDPv4, UDPv6 and L2. The default
is UDPv4.

net_sync_monitor
Enables the NetSync Monitor (NSM) protocol. The NSM protocol allows a station to
measure how well another node is synchronized. The monitor sends a unicast delay
request to the node, which replies unconditionally with unicast delay response,
sync, and follow up messages. If the monitor is synchronized to the GM, it can use
the time stamps in the message to estimate the node's offset. This option requires
that the 'hybrid_e2e' option be enabled as well. The default is 0 (disabled).

operLogPdelayReqInterval
The Pdelay Request messages interval to be used once the clock enters the
SERVO_LOCKED_STABLE state. If the 'msg_interval_request' option is set, then the
local client port will adopt this rate when the local clock enters the "locked
stable" state. This option is specified as a power of two in seconds, and the
default value is 0 (1 second).

operLogSyncInterval
The Sync message interval to be requested once the clock enters the
SERVO_LOCKED_STABLE state. If the 'msg_interval_request' option is set, then the
local client port will request the remote server to switch to the given message
rate via a signaling message containing a Message interval request TLV. This
option is specified as a power of two in seconds, and default value is 0 (1
second).

path_trace_enabled
Enable the mechanism used to trace the route of the Announce messages. The default
is 0 (disabled).

phc_index
Specifies the index of the PHC to be used for synchronization with hardware
timestamping. This option is useful with virtual clocks running on top of a free-
running physical clock (created by writing to /sys/class/ptp/ptp*/n_vclocks). The
default is -1, which means the index will be set to the PHC associated with the
interface, or the device specified by the -p option.

power_profile.2011.grandmasterTimeInaccuracy
Specifies the time inaccuracy of the GM in nanoseconds. Relevant only when
power_profile.version is 2011. This value may be changed dynamically using the
POWER_PROFILE_SETTINGS_NP management message. The default is -1 meaning unknown
inaccuracy.

power_profile.2011.networkTimeInaccuracy
Specifies the time inaccuracy of the network in nanoseconds. Relevant only when
power_profile.version is 2011. This value may be changed dynamically using the
POWER_PROFILE_SETTINGS_NP management message. The default is -1 meaning unknown
inaccuracy.

power_profile.2017.totalTimeInaccuracy
Specifies the sum of the GM, network, and local node inaccuracies in nanoseconds.
Relevant only when power_profile.version is 2017. This value may be changed
dynamically using the POWER_PROFILE_SETTINGS_NP management message. The default is
-1 meaning unknown inaccuracy.

power_profile.grandmasterID
Specifies an optional, non-zero identification code for the GM. Note that the code
is an arbitrary, power profile specific integer, not necessarily related to the
clockIdentity in any way. This value may be changed dynamically using the
POWER_PROFILE_SETTINGS_NP management message. The default is 0 meaning unused.

power_profile.version
Specifies the power profile version to be used. Valid values are "none", "2011",
or "2017". This value may be changed dynamically using the
POWER_PROFILE_SETTINGS_NP management message. The default is "none".

ptp_dst_mac
The MAC address to which PTP messages should be sent. Relevant only with L2
transport. The default is 01:1B:19:00:00:00.

p2p_dst_mac
The MAC address to which peer delay messages should be sent. Relevant only with L2
transport. The default is 01:80:C2:00:00:0E.

serverOnly
Setting this option to one (1) prevents the port from entering the client state. In
addition, the local clock will ignore Announce messages received on this port. This
option's intended use is to support the Telecom Profiles according to ITU-T
G.8265.1, G.8275.1, and G.8275.2. The default value is zero or false.

syncReceiptTimeout
The number of sync/follow up messages that may go missing before triggering a Best
Master Clock election. This option is used for running in gPTP mode according to
the 802.1AS-2011 standard. Setting this option to zero will disable the sync
message timeout. The default is 0 or disabled.

transportSpecific
The transport specific field. Must be in the range 0 to 255. The default is 0.

tsproc_mode
Select the time stamp processing mode used to calculate offset and delay. Possible
values are filter, raw, filter_weight, raw_weight. Raw modes perform well when the
rate of sync messages (logSyncInterval) is similar to the rate of delay messages
(logMinDelayReqInterval or logMinPdelayReqInterval). Weighting is useful with
larger network jitters (e.g. software time stamping). The default is filter.

udp_ttl
Specifies the Time to live (TTL) value for IPv4 multicast messages and the hop
limit for IPv6 multicast messages. This option is only relevant with the IPv4 and
IPv6 UDP transports. The default is 1 to restrict the messages sent by ptp4l to the
same subnet.

unicast_listen
When enabled, this option allows the port to grant unicast message contracts.
Incoming requests for will be granted limited only by the amount of memory
available. The default is 0 (disabled).

unicast_master_table
When set to a positive integer, this option specifies the table id to be used for
unicast discovery. Each table lives in its own section and has a unique, positive
numerical ID. Entries in the table are a pair of transport type and protocol
address. The default is 0 (unicast discovery disabled).

unicast_req_duration
The service time in seconds to be requested during unicast discovery. Note that
the remote node is free to grant a different duration. The default is 3600 seconds
or one hour.

PROGRAM AND CLOCK OPTIONS

asCapable
If set to 'true', all the checks which can unset asCapable variable (as described
in Section 10.2.4.1 of 802.1AS) are skipped. If set to 'auto', asCapable is
initialized to 'false' and will be set to 'true' after the relevant checks have
passed. The default value is 'auto'.

assume_two_step
Treat one-step responses as two-step if enabled. It is used to work around buggy
802.1AS switches. The default is 0 (disabled).

BMCA This option enables use of static roles for server and client devices instead of
running the best master clock algorithm (BMCA) described in 1588 profile. This can
be used to speed up the start time for servers and clients when you know the roles
of the devices in advance. When set to ´noop', the traditional BMCA algorithm used
by 1588 is skipped. masterOnly and clientOnly will be used to determine the server
or client role for the device. In a bridge, clientOnly (which is a global option)
can be set to make all ports assume the client role. masterOnly (which is a per-
port config option) can then be used to set individual ports to take on the server
role. The default value is 'ptp' which runs the BMCA related state machines.

check_fup_sync
Because of packet reordering that can occur in the network, in the hardware, or in
the networking stack, a follow up message can appear to arrive in the application
before the matching sync message. As this is a normal occurrence, and the
sequenceID message field ensures proper matching, the ptp4l program accepts out of
order packets. This option adds an additional check using the software time stamps
from the networking stack to verify that the sync message did arrive first. This
option is only useful if you do not trust the sequence IDs generated by the server.
The default is 0 (disabled).

clientOnly
The local clock is a client-only clock if enabled. The default is 0 (disabled).

clockAccuracy
The clockAccuracy attribute of the local clock. It is used in the PTP server
selection algorithm. The default is 0xFE.

clockClass
The clockClass attribute of the local clock. It denotes the traceability of the
time distributed by the grandmaster clock. The default is 248.

clock_class_threshold
The maximum clock class value from master, acceptible to sub-ordinate clock beyond
which it moves out of lock state. The default value is 248.

clockIdentity
The clockIdentity attribute of the local clock. The clockIdentity is an 8-octet
array and should in this configuration be written in textual form, see default. It
should be unique since it is used to identify the specific clock. If default is
used or if not set at all, the clockIdentity will be automtically generated. The
default is "000000.0000.000000"

clock_servo
The servo which is used to synchronize the local clock. Valid values are "pi" for a
PI controller, "linreg" for an adaptive controller using linear regression,
"ntpshm" and "refclock_sock" for the NTP SHM and chrony SOCK reference clocks
respectively to allow another process to synchronize the local clock, and "nullf"
for a servo that always dials frequency offset zero (for use in SyncE nodes). The
default is "pi."

clock_type
Specifies the kind of PTP clock. Valid values are "OC" for ordinary clock, "BC"
for boundary clock, "P2P_TC" for peer to peer transparent clock, and "E2E_TC" for
end to end transparent clock. An multi-port ordinary clock will automatically be
configured as a boundary clock. The default is "OC".

dataset_comparison
Specifies the method to be used when comparing data sets during the Best Master
Clock Algorithm. The possible values are "ieee1588" and "G.8275.x". The default
is "ieee1588".

domainNumber
The domain attribute of the local clock. The default is 0.

dscp_event
Defines the Differentiated Services Codepoint (DSCP) to be used for PTP event
messages. Must be a value between 0 and 63. There are several media streaming
standards out there that require specific values for this option. For example 46
(EF PHB) in AES67 or 48 (CS6 PHB) in RAVENNA. The default is 0.

dscp_general
Defines the Differentiated Services Codepoint (DSCP) to be used for PTP general
messages. Must be a value between 0 and 63. There are several media streaming
standards out there that recommend specific values for this option. For example 34
(AF41 PHB) in AES67 or 46 (EF PHB) in RAVENNA. The default is 0.

first_step_threshold
The maximum offset the servo will correct by changing the clock frequency (phase
when using nullf servo) instead of stepping the clock. This is only applied on the
first update. It's specified in seconds. When set to 0.0, the servo won't step the
clock on start. The default is 0.00002 (20 microseconds). This option used to be
called pi_f_offset_const.

free_running
Don't adjust the local clock if enabled. The default is 0 (disabled).

freq_est_interval
The time interval over which is estimated the ratio of the local and peer clock
frequencies. It is specified as a power of two in seconds. The default is 1 (2
seconds).

G.8275.defaultDS.localPriority
The Telecom Profiles (ITU-T G.8275.1 and G.8275.2) specify an alternate Best Master
Clock Algorithm (BMCA) with a unique data set comparison algorithm. The value of
this option is associated with the local clock and is used as a tie breaker
whenever clockClass, clockAccuracy, offsetScaledLogVariance, and priority2 are
equal. This option is only used when "dataset_comparison" is set to "G.8275.x".
The default value is 128.

gmCapable
If this option is enabled, then the local clock is able to become grand master.
This is only for use with 802.1AS clocks and has no effect on 1588 clocks. The
default is 1 (enabled).

ignore_source_id
This will disable source port identity checking for Sync and Follow_Up messages.
This is useful when the announce messages are disabled in the server and the client
does not have any way to know the server's identity. The default is 0 (disabled).

inhibit_announce
This will disable the timer for announce messages (i.e. FD_MANNO_TIMER) and also
the announce message timeout timer (i.e. FD_ANNOUNCE_TIMER). This is used by the
Automotive profile as part of switching over to a static BMCA. If this option is
enabled, ignore_source_id has to be enabled in the client because it has no way to
identify the server in the Sync and Follow_Up messages. The default is 0
(disabled).

initial_delay
The initial path delay of the clock in nanoseconds used for synchronization of the
clock before the delay is measured using the E2E or P2P delay mechanism. If set to
0, the clock will not be updated until the delay is measured. The default is 0.

interface_rate_tlv
When the client and server are operating are operating at different interface rate,
delay asymmetry caused due to different interface rate needs to be compensated.
The server sends its interface rate using interface rate TLV as per G.8275.2 Annex
D. The default is 0 (does not support interface rate tlv).

hwts_filter
Select the hardware time stamp filter setting mode. Possible values are normal,
check, full. Normal mode set the filters as needed. Check mode only check but do
not set. Full mode set the receive filter to mark all packets with hardware time
stamp,
so all applications can get them. The default is normal.

kernel_leap
When a leap second is announced, let the kernel apply it by stepping the clock
instead of correcting the one-second offset with servo, which would correct the
one-second offset slowly by changing the clock frequency (unless the step_threshold
option is set to correct such offset by stepping). Relevant only with software
time stamping. The default is 1 (enabled).

logging_level
The maximum logging level of messages which should be printed. The default is 6
(LOG_INFO).

manufacturerIdentity
The manufacturer id which should be an OUI owned by the manufacturer. The default
is 00:00:00.

max_frequency
The maximum allowed frequency adjustment of the clock in parts per billion (ppb).
This is an additional limit to the maximum allowed by the hardware. When set to 0,
the hardware limit will be used. The default is 900000000 (90%). This option used
to be called pi_max_frequency.

maxStepsRemoved
When using this option, if the value of stepsRemoved of an Announce message is
greater than or equal to the value of maxStepsRemoved the Announce message is not
considered in the operation of the BMCA. The default value is 255.

message_tag
The tag which is added to all messages printed to the standard output or system
log. The default is an empty string (which cannot be set in the configuration file
as the option requires an argument).

msg_interval_request
This option, when set, will trigger an adjustment to the Sync and peer delay
request message intervals when the clock servo transitions into the
SERVO_LOCKED_STABLE state. The Sync interval will be adjusted via the signaling
mechanism while the pdelay request interval is simply adjusted locally. The values
to use for the new Sync and peer delay request intervals are specified by the
operLogSyncInterval and operLogPdelayReqInterval options, respectively. The
default value of msg_interval_request is 0 (disabled).

ntpshm_segment
The number of the SHM segment used by ntpshm servo. The default is 0.

offsetScaledLogVariance
The offsetScaledLogVariance attribute of the local clock. It characterizes the
stability of the clock. The default is 0xFFFF.

pi_integral_const
The integral constant of the PI controller. When set to 0.0, the integral constant
will be set by the following formula from the current sync interval. The default
is 0.0.

ki = min(ki_scale * sync^ki_exponent, ki_norm_max / sync)

pi_integral_exponent
The ki_exponent constant in the formula used to set the integral constant of the PI
controller from the sync interval. The default is 0.4.

pi_integral_norm_max
The ki_norm_max constant in the formula used to set the integral constant of the PI
controller from the sync interval. The default is 0.3.

pi_integral_scale
The ki_scale constant in the formula used to set the integral constant of the PI
controller from the sync interval. When set to 0.0, the value will be selected from
0.3 and 0.001 for the hardware and software time stamping respectively. The
default is 0.0.

pi_proportional_const
The proportional constant of the PI controller. When set to 0.0, the proportional
constant will be set by the following formula from the current sync interval. The
default is 0.0.

kp = min(kp_scale * sync^kp_exponent, kp_norm_max / sync)

pi_proportional_exponent
The kp_exponent constant in the formula used to set the proportional constant of
the PI controller from the sync interval. The default is -0.3.

pi_proportional_norm_max
The kp_norm_max constant in the formula used to set the proportional constant of
the PI controller from the sync interval. The default is 0.7

pi_proportional_scale
The kp_scale constant in the formula used to set the proportional constant of the
PI controller from the sync interval. When set to 0.0, the value will be selected
from 0.7 and 0.1 for the hardware and software time stamping respectively. The
default is 0.0.

productDescription
The product description string. Allowed values must be of the form
manufacturerName;modelNumber;instanceIdentifier and contain at most 64 utf8
symbols. The default is ";;".

priority1
The priority1 attribute of the local clock. It is used in the PTP server selection
algorithm, lower values take precedence. Must be in the range 0 to 255. The
default is 128.

priority2
The priority2 attribute of the local clock. It is used in the PTP server selection
algorithm, lower values take precedence. Must be in the range 0 to 255. The
default is 128.

refclock_sock_address
The address of the UNIX domain socket to be used by the refclock_sock servo. The
default is /var/run/refclock.ptp.sock.

revisionData
The revision description string which contains the revisions for node hardware
(HW), firmware (FW), and software (SW). Allowed values are of the form HW;FW;SW and
contain at most 32 utf8 symbols. The default is an ";;".

sanity_freq_limit
The maximum allowed frequency offset between uncorrected clock and the system
monotonic clock in parts per billion (ppb). This is used as a sanity check of the
synchronized clock. When a larger offset is measured, a warning message will be
printed and the servo will be reset. If the frequency correction set by ptp4l
changes unexpectedly between updates of the clock (e.g. due to another process
trying to control the clock), a warning message will be printed. When set to 0, the
sanity check is disabled. The default is 200000000 (20%).

servo_num_offset_values
The number of offset values considered in order to transition from the SERVO_LOCKED
to the SERVO_LOCKED_STABLE state. The transition occurs once the last
'servo_num_offset_values' offsets are all below the 'servo_offset_threshold' value.
The default value is 10.

servo_offset_threshold
The offset threshold used in order to transition from the SERVO_LOCKED to the
SERVO_LOCKED_STABLE state. The transition occurs once the last
'servo_num_offset_values' offsets are all below the threshold value. The default
value of offset_threshold is 0 (disabled).

slave_event_monitor
Specifies the address of a UNIX domain socket for event monitoring. A local
monitoring client bound to this address will receive SLAVE_RX_SYNC_TIMING_DATA and
SLAVE_DELAY_TIMING_DATA_NP TLVs. The default is the empty string (disabled).

slaveOnly
This option is deprecated and will be removed in a future release. Use
"clientOnly" instead.

socket_priority
Configure the SO_PRIORITY of sockets. This is to support cases where a user wants
to route ptp4l traffic using Linux qdiscs for the purpose of traffic shaping. This
option is only available with the IEEE 802.3 transport (the -2 option) and is
silently ignored when using the UDP IPv4/6 network transports. Must be in the range
of 0 to 15, inclusive. The default is 0.

step_threshold
The maximum offset the servo will correct by changing the clock frequency (phase
when using nullf servo) instead of stepping the clock. When set to 0.0, the servo
will never step the clock except on start. It's specified in seconds. The default
is 0.0. This option used to be called pi_offset_const.

step_window
When set, indicates the number of Sync events after a clock step that the clock
will not do any frequency or step adjustments. This is used in situations where
clock stepping is unable to happen instantaneously so there is a lag before the
timestamps can settle properly to reflect the clock step. The default is 0
(disabled).

summary_interval
The time interval in which are printed summary statistics of the clock. It is
specified as a power of two in seconds. The statistics include offset root mean
square (RMS), maximum absolute offset, frequency offset mean and standard
deviation, and path delay mean and standard deviation. The units are nanoseconds
and parts per billion (ppb). If there is only one clock update in the interval, the
sample will be printed instead of the statistics. The messages are printed at the
LOG_INFO level. The default is 0 (1 second).

tc_spanning_tree
When running as a Transparent Clock, increment the "stepsRemoved" field of Announce
messages that pass through the switch. Enabling this option ensures that PTP
message loops never form, provided the switches all implement this option together
with the BMCA.

timeSource
The time source is a single byte code that gives an idea of the kind of local clock
in use. The value is purely informational, having no effect on the outcome of the
Best Master Clock algorithm, and is advertised when the clock becomes grand master.

time_stamping
The time stamping method to be used. The allowed values are hardware, software,
legacy, onestep, and p2p1step. The default is hardware.

twoStepFlag
Enable two-step mode for sync messages. One-step mode can be used only with
hardware time stamping. The default is 1 (enabled).

tx_timestamp_timeout
The number of milliseconds to poll waiting for the tx time stamp from the kernel
when a message has recently been sent. The default is 10.

udp6_scope
Specifies the desired scope for the IPv6 multicast messages. This will be used as
the second byte of the primary address. This option is only relevant with IPv6
transport. See RFC 4291. The default is 0x0E for the global scope.

uds_address
Specifies the address of the UNIX domain socket for receiving local management
messages. The default is /var/run/ptp4l.

uds_file_mode
File mode of the UNIX domain socket used for receiving local management messages.
The mode should be specified as an octal number, i.e. it should start with a 0
literal. The default mode is 0660.

uds_ro_address
Specifies the address of the second UNIX domain socket for receiving local
management messages, which is restricted to GET actions and does not forward
messages to other ports. Access to this socket can be given to untrusted
applications for monitoring purposes. The default is /var/run/ptp4lro.

uds_ro_file_mode
File mode of the second (read-only) UNIX domain socket used for receiving local
management messages. The mode should be specified as an octal number, i.e. it
should start with a 0 literal. The default mode is 0666.

use_syslog
Print messages to the system log if enabled. The default is 1 (enabled).

userDescription
The user description string. Allowed values are of the form name;location and
contain at most 128 utf8 symbols. The default is an empty string.

utc_offset
The current offset between TAI and UTC. The default is 37.

verbose
Print messages to the standard output if enabled. The default is 0 (disabled).

write_phase_mode
This option enables using the "write phase" feature of a PTP Hardware Clock. If
supported by the device, this mode uses the hardware's built in phase offset
control instead of frequency offset control. The default value is 0 (disabled).

UNICAST DISCOVERY OPTIONS

       L2|UDPv4|UDPv6
              Each  table  entry  specifies the transport type and network address of a potential
              remote server.  If multiple servers are specified, then unicast negotiation will be
              performed with each if them.

       logQueryInterval
              This  option  configures the time to wait between unicast negotiation attempts.  It
              is specified as a power of two in seconds.  The default is 0 (1 second).

       peer_address
              This option specifies the unicast address of the peer for use with the peer to peer
              delay  mechanism.   If  specified, the port owning the table will negotiate unicast
              peer delay responses from the machine at the given remote  address,  otherwise  the
              port will send multicast peer delay requests.

       table_id
              Each  table  must  begin  with a unique, positive table ID.  The port that claims a
              given table does so by including the ID as the value of its  'unicast_master_table'
              option.

TIME SCALE USAGE

       When  ptp4l  acts  as  the  domain  server,  it  either uses the PTP or the UTC time scale
       depending on time stamping mode.  In software and legacy time stamping modes it  announces
       Arbitrary  time scale mode, which is effectively UTC here.  In hardware time stamping mode
       it announces use of PTP time scale.

       When ptp4l is the domain server using hardware time stamping,  it  is  up  to  phc2sys  to
       maintain the correct offset between UTC and PTP times. See phc2sys(8) manual page for more
       details.