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Summary

Precision Time Protocol is used to synchronize clocks throughout the network. On a local area network, it achieves clock accuracy in the sub-microsecond range, making it suitable for measurement and control systems. RouterOS supports IEEE 1588-2008, PTPv2. Support is hardware dependant, please see the supported device list below.

Supported features:

  • Boundary/Ordinary clock
  • E2E delay mode
  • PTP delay mode
  • UDP over IPv4 multicast transport mode
  • L2 transport mode
  • priority1 can be configured to decide master/slave
  • PTP clock IS NOT synced with the system clock

General properties

Sub-menu: /system ptp


PropertyDescription
portSub-menu used for adding, removing, or viewing assigned ports
statusSub-menu that shows PTP ports, their state, and delay on slave ports
comment (string; Default: )

Short description of the PTP profile

name (string; Default: )Name of the PTP profile
delay-mode (auto | e2e | ptp; Default: auto)Configures delay mode for PTP profile
    • auto - selects delay mode automatically
    • e2e - use the delay request-response mechanism
    • ptp - use the peer delay mechanism
priority1 (integer [0..255]; auto; Default: auto)the priority value for influencing grandmaster election
profile (802.1as; default; g8275.1; Default: default)

IEEE 1588-2008 includes a profile concept defining PTP operating parameters and options. 

IEEE 802.1AS is an adaptation of PTP for use with Audio Video Bridging and Time-Sensitive Networking. Uses delay-mode=p2p, transport-mode=l2; recommends using priority1=auto.

g8275.1 profile is for frequency and phase synchronization in a fully PTP-aware network. Only allows priority1=auto (128), priority2=128, domain=24, delay-mode=e2e, transport=l2.

default profile, PTPv2 default configuration, allows for more configuration options than other profiles, but default values with auto settings correspond to: priority1=128. priority2=128, domain=0,transport=ipv4, delay-mode=e2e

transport (auto; ipv4;  l2; Default: auto)transport protocol to be used: IPv4 or layer2


For more details regarding Precision Time Protocol please see the following standards IEEE 1588 and IEEE 802.1as.

We strongly recommend keeping default/auto values, as there are different requirements between profiles. And assigning them manually can result in misconfiguration.

Configuration

To configure the device to participate in PTP you first need to create a PTP profile:

/system ptp add name=ptp1
#to view the created profile use
/system ptp print 
Flags: I - inactive, X - disabled 
0 name="ptp1" priority1=auto delay-mode=auto transport=auto profile=default

Note

Only 1 PTP profile is supported per device


After creating a PTP profile, you need to assign ports to it:

/system ptp port add interface=ether1 ptp=ptp1
#to view assigned ports use
/system ptp port print 
Flags: I - inactive 
0 ptp=ptp1 interface=ether8 

1 ptp=ptp1 interface=ether22 

To monitor the PTP profile, use the monitor command:

#on grandmaster device
[admin@grandmaster] > system ptp monitor numbers=0
name: test
clock-id: 64:D1:54:FF:FE:EB:AE:C3
priority1: 30
priority2: 128
i-am-gm: yes

#on non-grandmaster device
[admin@328] /system ptp monitor 0
name: ptp1
clock-id: 64:D1:54:FF:FE:EB:AD:C7
priority1: 128
priority2: 128
i-am-gm: no
gm-clock-id: 64:D1:54:FF:FE:EB:AE:C3
gm-priority1: 30
gm-priority2: 128
master-clock-id: 64:D1:54:FF:FE:EB:AE:C3
slave-port: ether8
freq-drift: 2147483647 ppb
offset: 1396202830 ns
hw-offset: 1306201921 ns
slave-port-delay: 2075668440 ns

Monitor properties

PropertyDescription
clock-id:local clock ID
priority1:priority1 value, depending on the PTP profile selected, an adjustable value used to influence the grandmaster election.
priority2:priority2 value, non-adjustable in RouterOS
i-am-gm: yes | noshows if the device is a grandmaster clock
gm-clock-id:grandmaster clock ID - Within a domain, a clock that is the ultimate source of time for clock synchronization using the protocol. 
gm-priority1:grandmaster priority1
gm-priority2:grandmaster priority2
master-clock-id:master clock ID - In the context of a single Precision Time Protocol (PTP) communication path, a clock that is the source of time to which all other clocks on that path synchronize. 
slave-port:shows which port is going towards the master or grandmaster clock
freq-drift:frequency drift in PPB (parts per billion) - time that would be lost every second in relation to the master clock, IF there was no synchronization.
offset:difference between clock values
hw-offset:offset difference from the hardware clock
slave-port-delay:the time it takes for a packet to be delivered to a directly connected device

Device support

Supported on:
CRS326-24G-2S+ supported only on Gigabit Ethernet ports
CRS328-24P-4S+ supported only on Gigabit Ethernet ports
CRS317-1G-16S+ supported on all ports
CRS326-24S+2Q+ supported on SFP+ and QSFP+ interfaces
CRS312-4C+8XG supported on all ports
CRS318-16P-2S+ supported only on Gigabit Ethernet ports
Not supported on:
CRS305-1G-4S+
CRS309-1G-8S+
CRS328-4C-20S-4S+
CRS354-48G-4S+2Q+

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