Precision Time Protocol (PTP) provides time synchronization among devices with submicrosecond accuracy. It provides also precise frequency synchronization.

Basic concepts

PTP profile

PTP profiles (PTP standards) include:

· IEEE 1588 version 2—1588v2 defines high-accuracy clock synchronization mechanisms. It can be customized, enhanced, or tailored as needed. 1588v2 is the latest version.

· ITU-T G.8275.1—G.8275.1 is introduced based on IEEE 1588. It is a precision time protocol telecom profile for phase and time synchronization with full timing support from the network.

PTP domain

A PTP domain refers to a network that is enabled with PTP. A PTP domain has only one reference clock called "grandmaster clock (GM)." All devices in the domain synchronize to the clock.

Clock node and PTP port

A node in a PTP domain is called a clock node. A port enabled with PTP is called a PTP port. IEEE 1588 version 2 defines the following types of basic clock nodes:

· Ordinary Clock (OC)—A PTP clock with a single PTP port in a PTP domain for time synchronization. It synchronizes time from its upstream clock node through the port. If an OC operates as the clock source, it sends synchronization time through a single PTP port to its downstream clock nodes.

· Boundary Clock (BC)—A clock with more than one PTP port in a PTP domain for time synchronization. A BC uses one of the ports to synchronize time from its upstream clock node. It uses the other ports to synchronize time to the relevant downstream clock nodes. If a BC operates as the clock source, such as BC 1 in Figure 1, it synchronizes time through multiple PTP ports to its downstream clock nodes.

· Transparent Clock (TC)—A TC does not keep time consistency with other clock nodes. A TC has multiple PTP ports. It forwards PTP messages among these ports and performs delay corrections for the messages, instead of performing time synchronization. TCs include the following types:

¡ End-to-End Transparent Clock (E2ETC)—Forwards non-P2P PTP messages in the network and calculates the delay of the entire link.

¡ Peer-to-Peer Transparent Clock (P2PTC)—Forwards only Sync, Follow_Up, and Announce messages, terminates other PTP messages, and calculates the delay of each link segment.

Figure 1 shows the positions of these basic clock nodes in a PTP domain.

Figure 1 Clock nodes and PTP ports in a PTP domain

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In addition to these basic types of clock nodes, PTP introduces hybrid clock nodes. For example, a TC+OC has multiple PTP ports in a PTP domain. One port is the OC type, and the others are the TC type.

A TC+OC forwards PTP messages through TC-type ports and performs delay corrections. In addition, it synchronizes time through its OC-type port. TC+OCs include these types: E2ETC+OC and P2PTC+OC.

Clock node and PTP port (ITU-T G.8275.1)

A node in a PTP domain is called a clock node. A port enabled with PTP is called a PTP port. ITU-T G.8275.1 defines the following types of basic clock nodes:

· Telecom boundary clock (T-BC)—A clock node with more than one PTP port in a PTP domain for time synchronization. It uses one of the ports to synchronize time to its upstream clock node and uses the other ports to distribute time to the downstream clock nodes. If a T-BC operates as the clock source, it distributes time through multiple PTP ports to its downstream clock nodes.

· Telecom transparent Clock (T-TC)—A clock code that forwards non-P2P PTP messages in the network. The forwarding duration will be included in calculation of the entire link delay.

· Telecom time slave clock (T-TSC) —An OC clock node (as defined in IEEE 1588 version 2 and IEEE 802.1AS) that can act only as a member clock.

Figure 1 shows the positions of these basic clock nodes in a PTP domain.

Figure 2 Clock nodes and PTP ports in a PTP domain (ITU-T G.8275.1)

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Master-member/subordinate relationship

The master-member/subordinate relationship is automatically determined based on the Best Master Clock (BMC) algorithm. You can also manually specify a role for the clock nodes.

The master-member/subordinate relationship is defined as follows:

· Master/Member node—A master node sends a synchronization message, and a member node receives the synchronization message.

· Master/Member clock—The clock on a master node is a master clock (parent clock) The clock on a member node is a member clock.

· Master/Subordinate/Passive port—A master port sends a synchronization message, and a subordinate port receives the synchronization message. The master and subordinate ports can be on a BC or an OC. A port that neither receives nor sends synchronization messages is a passive port.

Clock source type

A clock node supports the following clock sources:

· Local clock source—38.88 MHz clock signals generated by a crystal oscillator inside the clock monitoring module.

· External clock source—Clock signals generated by an external clock device. The signals are received and sent by a 1PPS/ToD port on the MPU. It is also called a ToD clock source.

Grandmaster clock

As shown in Figure 1, the grandmaster clock (GM) is the ultimate source of time for clock synchronization in a PTP domain. It is elected automatically by the clock nodes in the PTP domain. The clock nodes exchange PTP messages and elect the GM by comparing the clock priority, time class, and time accuracy carried in the PTP messages.

You can also specify a GM manually.

Grandmaster clock selection and master-member/subordinate relationship establishment

A GM can be manually specified. It can also be elected through the BMC algorithm.

IEEE 1588 version 2

A GM can be manually specified. It can also be automatically elected through the BMC algorithm as follows:

1. The clock nodes in a PTP domain exchange announce messages and elect a GM by using the following rules in descending order of precedence:

a. Clock node with higher priority 1.

b. Clock node with higher time class.

c. Clock node with higher time accuracy.

d. Clock node with higher priority 2.

e. Clock node with a smaller port ID (containing clock number and port number).

The master nodes, member nodes, master ports, and subordinate ports are determined during the process. Then a spanning tree with the GM as the root is generated for the PTP domain.

2. The master node periodically sends announce messages to the member nodes. If the member nodes do not receive announce messages from the master node, they determine that the master node is invalid, and they start to elect another GM.

ITU-T G.8275.1

A GM can be manually specified. It can also be automatically elected through the BMC algorithm as follows:

1. The clock nodes in a PTP domain exchange announce messages and elect a GM by using the following rules in descending order of precedence:

a. Clock node with higher time class.

b. Clock node with higher time accuracy.

c. Clock node with higher priority 2.

d. Clock node with higher local priority.

You can use the ptp priority clock-source command to set the local priority for the local node.

To set a local priority for the peer node, use the ptp local-priority command to set a local priority for the PTP interface connected to the peer node. This priority will be used as the local priority of the peer node.

e. Whether the time class values of the clock nodes are smaller than or equal to 127.

- If the time class values of the clock nodes are smaller than or equal to 127, two or more clock nodes are elected GMs in the PTP domain. A member node selects the GM nearer to it as its master node. Two or more spanning trees are generated. No PTP messages are exchanged between the trees.

- If the time class values of the clock nodes are greater than 127, the clock node with a smaller port ID (containing clock number and port number) will be the GM.

The master nodes, member nodes, master ports, and subordinate ports are determined during the process.

Synchronization mechanism

After master-member relationships are established between the clock nodes, the master and member clock nodes exchange PTP messages and record the message transmit and receive time. Based on the timestamps, each member clock calculates the path delay and time offset between them and the master clock and adjusts their time accordingly for time synchronization with the master clock.

PTP defines two path delay measurement mechanisms: Request_Response_ and Peer Delay, both of which are based on network symmetry.

Request_Response

The Request_Response mechanism measures the average path delay between the master and member clock nodes by using the PTP messages as shown in Figure 3. A TC between master and member clock nodes does not calculate the path delay. It forwards PTP messages and makes residence time correction on the Sync messages.

This mechanism can be implemented in one of the following two modes:

· Two-step mode—t1 is carried in the Follow_Up message as shown in Figure 3.

· Single-step mode—t1 is carried in the Sync message, and no Follow_Up message is sent. (The device does not support sing-step mode.)

Figure 3 shows the Request_Response mechanism in two-step mode.

1. The master clock sends a Sync message to the member clock, and records the sending time t1. Upon receiving the message, the member clock records the receiving time t2.

2. After sending the Sync message, the master clock immediately sends a Follow_Up message that carries time t1.

3. The member clock sends a Delay_Req message to the master clock, and records the sending time t3. Upon receiving the message, the master clock records the receiving time t4.

4. The master clock returns a Delay_Resp message that carries time t4.

After this procedure, the member clock obtains all the four timestamps and can make the following calculations:

· Round-trip delay between the master and member clocks: (t2 – t1) + (t4 – t3)

· One-way delay between the master and member clocks: [(t2 – t1) + (t4 – t3)] / 2

· Offset between the member and master clocks: (t2 – t1) – [(t2 – t1) + (t4 – t3)] / 2 or [(t2 – t1) – (t4 – t3)] / 2

Figure 3 Request_Response mechanism (two-step node)

Peer Delay

The Peer Delay mechanism measures the average path delay between two clock nodes by using Pdelay messages. The two clock nodes (BC, TC, or OC) using this mechanism send Pdelay messages to each other, and calculate the one-way link delay between them independently. The message interaction process and delay calculation method are identical on the two nodes. TCs that exist between master and member clock nodes divide the synchronization path into multiple links. Each TC makes link delay and residence time corrections on the Sync messages.

This mechanism can be implemented in one of the following two modes:

· Two-step mode

As shown in Figure 4, Pdelay messages include Pdelay_Req, Pdelay_Resp, and Pdelay_Resp_Follow_Up messages. t2 is carried in the Pdelay_Resp message, and t3 is carried in the Pdelay_Resp_Follow_Up message.

· Single-step mode:

Pdelay messages include Pdelay_Req and Pdelay_Resp messages. t3 – t2 is carried in the Pdelay_Resp, and no Pdelay_Resp_Follow_Up message is sent.

Figure 4 uses Clock node B as an example to describe the Peer Delay mechanism.

1. Clock node B sends a Pdelay_Req message to Clock node A, and records the sending time t1. Upon receiving the message, Clock node A records the receiving time t2.

2. Clock node A sends a Pdelay_Req message that carries t2 to Clock node B, and records the sending time t3. Upon receiving the message, Clock node B records the receiving time t4.

3. Clock node A immediately sends a Pdelay_Resp_Follow_Up message carrying t3 to Clock node B after sending the Pdelay_Req message.

After this procedure, Clock node B obtains all the four timestamps and can make the following calculations:

· Round-trip delay between Clock node A and Clock node B: (t2 – t1) + (t4 – t3)

· One-way delay between Clock node A and Clock node B: [(t2 – t1) + (t4 – t3)] / 2 = [(t3 – t2) + (t4 – t1)] / 2

· Time offset between the member clock and the master clock: Sync message receiving time on the member clock – Sync message sending time on the master clock – Total one-way delays on all links – Total PTP message residence time on all TCs.

Figure 4 Peer Delay mechanism (two-step mode)

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Protocols and standards

· IEEE Std 1588-2008, IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems, 2008

· ITU-T G.8275.1, Precision time protocol telecom profile for phase/time synchronization with full timing support from the network

Restrictions and guidelines: PTP configuration

Before configuring PTP, determine the PTP standard and define the scope of the PTP domain and the role of every clock node.

Only the default MDC supports PTP. Non-default MDCs do not support PTP or PTP commands. For more information about MDCs, see Virtual Technologies Configuration Guide.

PTP tasks at a glance

Configuring PTP (IEEE 1588 version 2)

1. Specifying PTP for obtaining the time

2. Specifying a PTP profile

Specify the IEEE 1588 version 2 PTP profile.

3. Configuring clock nodes

¡ Specifying a clock node type

¡ (Optional.) Configuring an OC to operate only as a member clock

4. (Optional.) Specifying a PTP domain

5. Enabling PTP on a port

6. Configuring PTP ports

¡ (Optional.) Configuring the role of a PTP port

¡ Configuring the mode for carrying timestamps

¡ Specifying a delay measurement mechanism

¡ Configuring one of the ports on a TC+OC clock as an OC-type port

7. (Optional.) Configuring PTP message transmission and receiving

¡ Setting the interval for sending announce messages and the timeout multiplier for receiving announce messages

¡ Setting the interval for sending Pdelay_Req messages

¡ Setting the interval for sending Sync messages

¡ Setting the minimum interval for sending Delay_Req messages

8. (Optional.) Configuring parameters for PTP messages

¡ Specifying the IPv4 UDP transport protocol for PTP messages

¡ Configuring a source IP address for multicast

¡ Configuring a destination IP address for unicast

¡ Configuring the destination MAC address for PTP messages

¡ Setting a DSCP value for PTP messages transmitted over UDP

¡ Specifying a VLAN tag for PTP messages

9. (Optional.) Disabling PTP path tracing

10. (Optional.) Specifying the maximum number of removed steps (clock nodes) from the GM to the device

11. (Optional.) Enabling the device to notify the downstream nodes of its time synchronization state

12. (Optional.) Adjusting and correcting clock synchronization

¡ Setting the delay correction value

¡ Setting the cumulative offset between the UTC and TAI

¡ Setting the correction date of the UTC

¡ Configuring ToD input or output

13. (Optional.) Setting clock source parameters

14. (Optional.) Configuring a priority for a clock (IEEE 1588 version 2)

15. (Optional.) Configuring PTP logging

Configuring PTP (ITU-T G.8275.1)

1. Specifying PTP for obtaining the time

2. Specifying a PTP profile

Specify the ITU-T G.8275.1 PTP profile.

3. Specifying a clock node type

4. (Optional.) Specifying a PTP domain

5. Enabling PTP on a port

6. Configuring PTP ports

¡ (Optional.) Configuring the role of a PTP port

¡ Configuring the mode for carrying timestamps

7. (Optional.) Configuring PTP message transmission and receiving

¡ Setting the interval for sending announce messages and the timeout multiplier for receiving announce messages

¡ Setting the interval for sending Sync messages

¡ Setting the minimum interval for sending Delay_Req messages

8. (Optional.) Configuring parameters for PTP messages

¡ Configuring the destination MAC address for PTP messages

¡ Specifying a VLAN tag for PTP messages

9. (Optional.) Disabling PTP path tracing

10. (Optional.) Specifying the maximum number of removed steps (clock nodes) from the GM to the device

11. (Optional.) Enabling the device to notify the downstream nodes of its time synchronization state

12. (Optional.) Adjusting and correcting clock synchronization

¡ Setting the delay correction value

¡ Setting the cumulative offset between the UTC and TAI

¡ Setting the correction date of the UTC

¡ Configuring ToD input or output

13. (Optional.) Setting clock source parameters

14. (Optional.) Configuring PTP logging

Specifying PTP for obtaining the time

1. Enter system view.

system-view

2. Specify PTP for obtaining the time.

clock protocol ptp mdc 1

By default, the device uses NTP to obtain the system time.

The device supports PTP configuration only on the default MDC. The ID of the default MDC is 1. You must specify the default MDC for this command to take effect.

For more information about the clock protocol command, see device management commands in Fundamentals Command Reference.

Specifying a PTP profile

Restrictions and guidelines

You must specify a PTP profile before configuring PTP settings. Changing the PTP profile clears all settings under the profile.

Procedure

1. Enter system view.

system-view

2. Specify a PTP profile.

ptp profile { 1588v2 | g8275.1 }

By default, no PTP profile is specified for the device.

Configuring clock nodes

Specifying a clock node type

Restrictions and guidelines

You can specify only one clock node type for the device. The supported clock node types include OC, BC, E2ETC, P2PTC, E2ETC+OC, P2PTC+OC, T-BC, T-TC, and T-TSC.

Before you specify a clock node type, specify a PTP profile.

· When the PTP profile is IEEE 1588 version 2, you cannot specify the T-BC, T-TC, or T-TSC clock node type.

· When the PTP profile is ITU-T G.8275.1, you can specify only the T-BC, T-TC, or T-TSC clock node type.

Changing or removing the clock node type restores the default settings of the PTP profile.

Procedure

1. Enter system view.

system-view

2. Specify a clock node type.

ptp mode { bc | e2etc | e2etc-oc | oc | p2ptc | p2ptc-oc | t-bc | t-tc | t-tsc }

By default, no clock node type is specified.

Configuring an OC to operate only as a member clock

About this task

An OC can operate either as a master clock to send synchronization messages or as a member clock to receive synchronization messages. This task allows you to configure an OC to operate only as a member clock.

If an OC is operating only as a member clock, you can use the ptp force-state command to configure its PTP port as a master port or passive port.

Restrictions and guidelines

This task is applicable only to OCs.

Procedure

1. Enter system view.

system-view

2. Configure the OC to operate only as a member clock.

ptp slave-only

By default, an OC operates as a master or member clock.

Specifying a PTP domain

About this task

Within a PTP domain, all devices follow the same rules to communicate with each other. Devices in different PTP domains cannot exchange PTP messages.

Procedure

1. Enter system view.

system-view

2. Specify a PTP domain for the device.

ptp domain value

The default settings of this command depends on the PTP profile.

¡ The device is in PTP domain 0 When the PTP profile is IEEE 1588 version 2.

¡ The device is in PTP domain 24 when the PTP profile is ITU-T G.8275.1.

Enabling PTP on a port

About this task

A port enabled with PTP becomes a PTP port.

Restrictions and guidelines

You can enable PTP on only one port on an OC or T-TSC clock node..

To enable PTP on a Layer 3 Ethernet interface that has been assigned to a VPN instance, you must specify this VPN instance in the ptp source ip-address vpn-instance vpn-instance-name command if PTP messages are to be transmitted in multicast mode over IPv4 UDP.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Enable PTP on the port.

ptp enable

By default, PTP is disabled on a port.

Configuring PTP ports

Configuring the role of a PTP port

About this task

You can configure the master, passive, or slave role for a PTP port.

For an OC that operates in slave-only mode, you can perform this task to change its PTP port role to master or slave.

Restrictions and guidelines

By default, the PTP port roles are automatically negotiated based on the BMC algorithm. If you use this command to change the role of one PTP port, all the other PTP ports in the PTP domain stop working. For these PTP ports to function, you must specify roles for each of them by using this command. As a best practice, enable automatic negotiation of PTP port roles based on the BMC algorithm.

You can configure only one subordinate port on a device.

After you change the role of a PTP port, you must execute the ptp active force-state command to activate the port role configuration.

This task is not available for a T-TSC clock node.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Configure the role of the PTP port.

ptp force-state { master | passive | slave }

By default, the PTP port role is automatically calculated through BMC.

4. Return to system view.

quit

5. Activate the port role configuration.

ptp active force-state

By default, the port role configuration is not activated.

Configuring the mode for carrying timestamps

About this task

The device supports the two-step timestamp carrying mode. In this mode, the Sync message (in the Request_Response or Peer Delay mechanism) and Pdelay_Resp message (in the Peer Delay mechanism) do not carry their sending timestamps. The subsequent messages carry their timestamps.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Configure the mode for carrying timestamps.

ptp clock-step two-step

By default, two-step mode is used for carrying timestamps.

Specifying a delay measurement mechanism

Restrictions and guidelines

PTP defines two transmission delay measurement mechanisms: Request_Response and Peer Delay. For correct communication, ports on the same link must share the same delay measurement mechanism.

Under the IEEE 1588 version 2 PTP profile, you can configure this task only for BCs and OCs. The delay measurement mechanism is Request_Response for E2ETCs and E2ETC+OCs and Peer Delay for P2PTCs and P2PTC+OCs. You cannot change the delay measurement mechanism for these clock nodes.

The ITU-T G.8275.1 PTP profile supports only the request-response delay measurement mechanism and does not support this task.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Specify a delay measurement mechanism.

ptp delay-mechanism { e2e | p2p }

The e2e keyword specifies the Request_Response mechanism, and the p2p keyword specifies the Peer Delay mechanism.

The default delay measurement mechanism varies by PTP profile:

¡ IEEE 1588 version 2—Request_Response mechanism.

¡ ITU-T G.8275.1—Request_Response mechanism.

Configuring one of the ports on a TC+OC clock as an OC-type port

About this task

All ports on a TC+OC (E2ETC+OC or P2PTC+OC) are TC-type ports by default. This feature allows you to configure one of the ports on a TC+OC clock as an OC-type port.

Restrictions and guidelines

This task is applicable only to E2ETC+OCs and P2PTC+OCs.

For time synchronization accuracy, the OC-type port on an E2ETC+OC or P2PTC+OC must be specified as the master port.

This task is not supported under the ITU-T G.8275.1 PTP profile.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Configure the port type as OC.

ptp port-mode oc

By default, the port type for all ports on a TC+OC is TC.

Configuring PTP message transmission and receiving

Setting the interval for sending announce messages and the timeout multiplier for receiving announce messages

About this task

A master node sends announce messages to the member nodes at the specified interval. If a member node does not receive any announce message from the master node after the timeout expires, it determines that the master node is invalid. The timeout = timeout multiplier × interval at which the master node sends announce messages.

About this task

A master node periodically sends announce messages to the member nodes. If a member node does not receive any announce message from the master node within multiple-value times the announce message sending interval configured on the master node, it determines that the master node is invalid.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Set the interval for sending announce messages.

ptp announce-interval interval

The default varies by PTP profile:

¡ IEEE 1588 version 2—The interval argument value is 1 and the interval for sending announce messages is 2 (21) seconds.

¡ ITU-T G.8275.1—The interval argument value is –3 and the interval for sending announce messages is 1/8 (2-3) seconds.

4. Set the number of intervals before a timeout occurs.

ptp announce-timeout multiple-value

By default, a timeout occurs when three intervals are reached.

Setting the interval for sending Pdelay_Req messages

Restrictions and guidelines

The ITU-T G.8275.1 PTP profile does not support this task

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Set the interval for sending Pdelay_Req messages.

ptp pdelay-req-interval interval

By default, the interval argument value is 0 and the interval for sending peer delay request messages is 1 (20) second.

Setting the interval for sending Sync messages

About this task

This task allows you to configure the interval at which the master node sends Sync messages to the member nodes. You must configure this task on the master node.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Set the interval for sending Sync messages.

ptp syn-interval interval

The default varies by PTP profile:

¡ IEEE 1588 version 2—The interval argument value is 0 and the interval for sending Sync messages is 1 (20) second.

¡ ITU-T G.8275.1—The interval argument value is –4 and the interval for sending Sync messages is 1/16 (2-4) seconds.

Setting the minimum interval for sending Delay_Req messages

About this task

When receiving a Sync or Follow_Up message, an interface can send Delay_Req messages only when the minimum interval is reached.

Restrictions and guidelines

In PTP multicast transport mode, this setting takes effect only when configured on the master clock. The master clock sends the value to a member clock through PTP messages to control the interval for the member clock to send Delay_Req messages. To view the value on a member clock, execute the display ptp interface command on the member clock.

In PTP unicast transport mode, this setting takes effect when configured on member clocks. It does not take effect when configured on the master clock.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Set the minimum interval for sending Delay_Req messages.

ptp min-delayreq-interval interval

The default setting varies by PTP profile.

¡ IEEE 1588 version 2—The value of the interval argument is 0 and the minimum interval for sending delay request messages is 1 (20) second.

¡ ITU-T G.8275.1—The value of the interval argument is –4 and the minimum interval for sending delay request messages is 1/16 (2-4) seconds.

Configuring parameters for PTP messages

Specifying the IPv4 UDP transport protocol for PTP messages

About this task

PTP messages can be encapsulated in IEEE 802.3/Ethernet packets or UDP packets.

Restrictions and guidelines

The ITU-T G.8275.1 profile supports only IEEE 802.3/Ethernet encapsulation of PTP messages and does not support this task.

The ITU-T G.8275.2 PTP profile supports only UDP encapsulation of PTP messages and does not support this task.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Specify the IPv4 UDP transport protocol for PTP messages.

ptp transport-protocol udp

By default, PTP messages are encapsulated in IEEE 802.3/Ethernet packets.

Configuring a source IP address for multicast PTP messages transmitted over IPv4 UDP

About this task

To transport multicast PTP messages over IPv4 UDP, you must configure a source IP address for the messages.

Restrictions and guidelines

If a source IP address for multicast PTP messages transmitted over IPv4 UDP and a destination address for unicast PTP messages transmitted over IPv4 UDP are both configured, the system unicasts the messages.

This task is not available under the ITU-T G.8275.1 PTP profile.

Procedure

1. Enter system view.

system-view

2. Configure a source IP address for multicast PTP messages transmitted over IPv4 UDP.

ptp source ip-address [ vpn-instance vpn-instance-name ]

By default, no source IP address is configured for multicast PTP messages transmitted over IPv4 UDP.

Configuring a destination IP address for unicast PTP messages transmitted over IPv4 UDP

About this task

Both unicast and multicast PTP messages can be transmitted over UDP.

The destination IP address for multicast PTP messages transmitted over IPv4 UDP is 224.0.1.129 or 224.0.0.107, which cannot be modified. 224.0.1.129 and 224.0.0.107 are the destination IP addresses for messages in the Request_Response and Peer Delay mechanism, respectively.

To transmit unicast PTP messages over UDP, you must configure a destination IP address for the messages.

Restrictions and guidelines

This task is not available under the ITU-T G.8275.1 PTP profile.

Prerequisites

Configure an IP address for the current interface, and make sure the interface and the peer PTP interface can reach each other.

Procedure

1. Enter system view.

system-view

2. Enter Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Configure a destination IP address for unicast PTP messages transmitted over IPv4 UDP.

ptp unicast-destination ip-address

By default, no destination IP address is configured for unicast PTP messages transmitted over IPv4 UDP.

Configuring the destination MAC address for PTP messages

About this task

IEEE 802.3/Ethernet-encapsulated PTP messages can be sent through multicast or unicast. The destination MAC address for PTP messages can be as follows:

· Any unicast MAC address in unicast mode.

· In multicast mode:

¡ 0180-C200-000E or 011B-1900-0000 for non-Pdelay messages, including delay_Req, delay_Resp, delay_Resp_Follow_Up, Announce, Sync, and FollowUp messages.

¡ 0180-C200-000E for Pdelay messages, including Pdelay_Req, Pdelay_Resp, and Pdelay_Resp_Follow_Up messages.

Restrictions and guidelines

You must specify the PTP profile and a PTP mode before configuring this feature.

This feature takes effect only when PTP messages are encapsulated in IEEE 802.3/Ethernet packets.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Configure the destination MAC address for PTP messages.

ptp destination-mac mac-address

By default, the destination MAC address for non-Pdelay messages is 011B-1900-0000 and the destination MAC address for Pdelay messages is 0180-C200-000E.

Setting a DSCP value for PTP messages transmitted over UDP

About this task

The DSCP value determines the sending precedence of PTP messages transmitted over UDP.

Restrictions and guidelines

This task is not available under the ITU-T G.8275.1 PTP profile.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Set a DSCP value for PTP messages transmitted over IPv4 UDP.

ptp dscp dscp

By default, the DSCP value is 56.

Specifying a VLAN tag for PTP messages

About this task

Perform this task to configure the VLAN ID and the 802.1p precedence in the VLAN tag carried by PTP messages.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view.

interface interface-type interface-number

3. Specify a VLAN tag for PTP messages.

ptp vlan vlan-id [ dot1p dot1p-value ]

By default, PTP messages do not have a VLAN tag.

Disabling PTP path tracing

About this task

PTP path tracing traces the clock nodes that the clock signals traverse from the GM to the device. The system can obtain complete path tracing information only when all clock nodes on the path are enabled with PTP path tracing. If a device on the path does not support PTP path tracing, disable this feature to prevent PTP intercommunication issues.

Procedure

1. Enter system view.

system-view

2. Disable PTP path tracing.

ptp path-trace disable

By default, PTP path tracing is enabled.

Specifying the maximum number of removed steps (clock nodes) from the GM to the device

About this task

If the number of removed steps from the GM to the device on the PTP synchronization path is too large, the time synchronization accuracy will decrease. After you specify the maximum number of removed steps from the GM to the device, the device cannot synchronize time through PTP if the number of the removed steps exceeds the maximum value.

Procedure

1. Enter system view.

system-view

2. Specify the maximum number of removed steps from the GM to the device.

ptp max-steps-removed step-removed-value

By default, the maximum number of removed steps from the GM to the device is 255.

Enabling the device to notify the downstream nodes of its time synchronization state

About this task

The task enables the device to notify its downstream nodes of its time synchronization state.

By default, the device transfers only the locked and unlocked status of the upstream node to the downstream nodes, and does not transfer its locked or unlocked status to the downstream nodes.

After this task is configured, the device notifies the downstream nodes of its locked and unlocked status through the synchronizationUncertain flag in the announce messages. The downstream nodes do not synchronize to the device when they receive information that the device time is unlocked and synchronize to the device when they receive information that the device time is locked.

Restrictions and guidelines

This task is available only for the IEEE 1588 version 2 and ITU-T G.8275.1 PTP profiles.

Procedure

1. Enter system view.

system-view

2. Enable the device to notify the downstream nodes of its time synchronization state.

ptp sync-uncertain enable

By default, the device does not notify the downstream nodes of its time synchronization state.

Adjusting and correcting clock synchronization

Setting the delay correction value

About this task

PTP performs time synchronization based on the assumption that the delays in sending and receiving messages are the same. However, this is not practical. If you know the offset between the delays in sending and receiving messages, you can set the delay correction value for more accurate time synchronization.

Procedure

1. Enter system view.

system-view

2. Enter Layer 2 Ethernet interface view or Layer 3 Ethernet interface view.

interface interface-type interface-number

3. Set a delay correction value.

ptp asymmetry-correction { minus | plus } value

The default is 0 nanoseconds. Delay correction is not performed.

Setting the cumulative offset between the UTC and TAI

About this task

An offset exists between Coordinated Universal Time (UTC) and International Atomic Time (TAI). The device displays the UTC time. However, PTP uses TAI for time synchronization. For the device to synchronize correct time to other clock nodes in the PTP domain when its local clock is selected as the GM, configure this task to correct the offset between UTC and TAI.

Procedure

1. Enter system view.

system-view

2. Set the cumulative offset between the UTC and TAI.

ptp utc offset utc-offset

The default is 0 seconds.

Setting the correction date of the UTC

About this task

This task allows you to adjust the UTC at the last minute (23:59) of the specified date.

Restrictions and guidelines

If you configure the setting multiple times, the most recent configuration takes effect.

This task takes effect only when configured on the master clock node, and the local clock of the master clock node is the GM.

Procedure

1. Enter system view.

system-view

2. Set the correction date of the UTC.

ptp utc { leap59-date | leap61-date } date

By default, the correction date of the UTC is not configured.

Configuring ToD input or output

About this task

To use a ToD clock, you must configure ToD input or output:

· ToD input—The device obtains clock signals from an external ToD clock and synchronizes ToD to all cards on the device.

· ToD output—The device operates as a ToD clock to synchronize ToD to other devices in the PTP network.

To implement more accurate time synchronization, you can specify a delay correction value.

Restrictions and guidelines

Do not configure the device to receive both ToD 0 and ToD 1 clock signals.

Procedure

1. Enter system view.

system-view

2. Configure ToD input or output.

ptp { tod0 | tod1 } { input [ delay input-delay-time ] | output [ delay output-delay-time ] }

By default, the device transmits ToD clock signals from ToD 0 and ToD 1. The transmit and receive delay correction value is 0 nanoseconds.

Setting clock source parameters

Restrictions and guidelines

The clock's time class is an attribute of the device. For a local clock source, keep its default time class and do not modify it as a best practice.

Procedure

1. Enter system view.

system-view

2. Set clock source parameters. Choose the options to configure as needed:

¡ ptp clock-source local { accuracy acc-value | class class-value | time-source ts-value }

¡ ptp clock-source { tod0 | tod1 } { accuracy acc-value | class class-value | time-source ts-value | grandmaster-clockid clock-id | offsetscaled-logvariance value }

The default settings for clock source parameters vary by PTP profile and PTP technical standard.

· The clock ID of a GM clock is 000000-0000-000000.

· ITU-T G.8275.1 PTP profile

¡ T-TSC clock node type

- Local clock source—The accuracy value is 254, the time class value is 255, the offset (log variance) value is 65535, and the time source value is 160. The four values are fixed, not configurable.

- ToD clock source—The accuracy value is 254, the time class value is 255, the offset (log variance) value is 65535, and the time source value is 32.

¡ T-BC or T-TC clock node type

- Default PTP technical standard

Local clock source—The accuracy value is 37, the time class value is 248, the offset (log variance) value is 65535, and the time source value is 160.

ToD clock source—The accuracy value is 32, the time class value is 6, the offset (log variance) value is 65535, and the time source value is 32.

· IEEE 1588 version 2 PTP profile

¡ Local clock source—The accuracy value is 37, the time class value is 248, the offset (log variance) value is 65535, and the time source value is 160. The offset (log variance) value not configurable.

¡ ToD clock source—The accuracy value is 32, the time class value is 6, the offset (log variance) is 65535, and the time source value is 32.

Configuring clock priorities

Configuring a priority for a clock (IEEE 1588 version 2)

About this task

Priorities for clocks are used to elect the GM. The smaller the priority value, the higher the priority.

Procedure

1. Enter system view.

system-view

2. Configure the priority for a clock .

ptp priority clock-source { local | tod0 | tod1 } { priority1 priority1 | priority2 priority2 }

When the PTP profile is IEEE 1588 version 2, the default value for both priority 1 and priority 2 is 128.

Configuring PTP logging

About this task

PTP logs help monitor the clock source status. The following PTP logs are available:

· PTP log that indicates a lower time class

Each PTP clock source has a class value. For a ToD clock source, you can set its class value by using the ptp clock-source command. The higher the value, the lower the class. When the class value of the clock source crosses the class threshold, the system outputs a log for notification.

· PTP log that indicates a higher time offset between the external reference clock and the PTP clock

If the device uses an external reference clock, it periodically calculates the time offset between the external reference clock and the PTP clock. When the offset exceeds the threshold, the device outputs a log for notification

· PTP logs that indicate a higher time-offset-sum peak-to-peak value

The PTP module calculates the time-offset-sum peak-to-peak value at specific intervals and compares the value with the threshold configured by this command. If the value is larger than the threshold, the system outputs a log for notification.

· PTP logs that indicate the time-locked or time-unlocked state

When the time offset of the PTP reference clock crosses the PTP time locking threshold, the PTP time is put into unlocked state. The system outputs a time-unlocked log for notification. When the time offset of the PTP reference clock drops to or below the PTP time locking threshold, the PTP time is put into locked state. The system outputs a time-locked log for notification.

Restrictions and guidelines

Only the IEEE 1588 version 2 and ITU-T G.8275.1 PTP profiles support this task.

Procedure

1. Enter system view.

system-view

2. Configure the class threshold for the clock source.

ptp alarm-threshold clock-source-class class-value

By default, the class threshold for the clock source is 6.

3. Configure the time-offset threshold between the external reference clock and the PTP clock.

ptp alarm-threshold time-offset time-offset-value

By default, the time-offset threshold is 500 ns between the external reference clock and the PTP clock.

4. Set the time-offset-sum peak-to-peak threshold.

ptp alarm-threshold time-offset-sum pk-pk threshold-value

By default, the time-offset-sum peak-to-peak threshold is 500 ns.

Display and maintenance commands for PTP

Execute display commands in any view and the reset command in user view.

Task	Command
Display PTP clock information.	display ptp clock
Display the delay correction history.	display ptp corrections
Display information about foreign master nodes.	display ptp foreign-masters-record [ interface interface-type interface-number ]
Display PTP information on an interface.	display ptp interface [ interface-type interface-number \| brief ]
Display parent node information for the PTP device.	display ptp parent
Display brief information about the PTP synchronization path from the GM to the device.	display ptp path-trace
Display PTP statistics.	display ptp statistics [ interface interface-type interface-number ]
Display PTP clock time properties.	display ptp time-property
Clear PTP statistics.	reset ptp statistics [ interface interface-type interface-number ]

PTP configuration examples

Example: Configuring PTP (IEEE 1588 version 2, IEEE 802.3/Ethernet transport, multicast transmission)

Network configuration

As shown in Figure 5, configure PTP (IEEE 1588 version 2, IEEE 802.3/Ethernet transport, multicast transmission) to enable time synchronization between Device A and Device C.

· Specify the IEEE 1588 version 2 PTP profile and multicast IEEE 802.3/Ethernet transport of PTP messages for Device A, Device B, and Device C.

· Assign Device A, Device B, and Device C to the same PTP domain. Specify the OC clock node type for Device A and Device C, and E2ETC clock node type for Device B. All clock nodes elect a GM through BMC in the PTP domain.

· Use the default Request_Response delay measurement mechanism on Device A and Device C.

Figure 5 Network diagram

‌

Procedure

1. Configure Device A:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceA> system-view

[DeviceA] ptp profile 1588v2

# Specify the OC clock node type.

[DeviceA] ptp mode oc

# Specify PTP for obtaining the time on the default MDC.

[DeviceA] clock protocol ptp mdc 1

# Enable PTP on GigabitEthernet 1/2/0/1.

[DeviceA] interface gigabitethernet 1/2/0/1

[DeviceA-GigabitEthernet1/2/0/1] ptp enable

[DeviceA-GigabitEthernet1/2/0/1] quit

2. Configure Device B:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceB> system-view

[DeviceB] ptp profile 1588v2

# Specify the E2ETC clock node type.

[DeviceB] ptp mode e2etc

# Specify PTP for obtaining the time on the default MDC.

[DeviceB] clock protocol ptp mdc 1

# Enable PTP on GigabitEthernet 1/2/0/1.

[DeviceB] interface gigabitethernet 1/2/0/1

[DeviceB-GigabitEthernet1/2/0/1] ptp enable

[DeviceB-GigabitEthernet1/2/0/1] quit

# Enable PTP on GigabitEthernet 1/2/0/2.

[DeviceB] interface gigabitethernet 1/2/0/2

[DeviceB-GigabitEthernet1/2/0/2] ptp enable

[DeviceB-GigabitEthernet1/2/0/2] quit

3. Configure Device C:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceC> system-view

[DeviceC] ptp profile 1588v2

# Specify the OC clock node type.

[DeviceC] ptp mode oc

# Specify PTP for obtaining the time on the default MDC.

[DeviceC] clock protocol ptp mdc 1

# Enable PTP on GigabitEthernet 1/2/0/1.

[DeviceC] interface gigabitethernet 1/2/0/1

[DeviceC-GigabitEthernet1/2/0/1] ptp enable

[DeviceC-GigabitEthernet1/2/0/1] quit

Verifying the configuration

When the network is stable, perform the following tasks:

· Use the display ptp clock command to display PTP clock information.

· Use the display ptp interface brief command to display brief PTP running information for all PTP interfaces.

# Display PTP clock information on Device A.

[DeviceA] display ptp clock

PTP profile : IEEE 1588 Version 2

PTP mode : OC

Slave only : No

Sync uncertain : Disabled

Clock state : Disabled

Clock ID : 000FE2-FFFE-FF0000

Clock type : Local

Clock domain : 0

Number of PTP ports : 1

Priority1 : 128

Priority2 : 128

Clock quality :

Class : 248

Accuracy : 254

Offset (log variance) : 65535

Offset from master : 0 (ns)

Mean path delay : 0 (ns)

Steps removed : 0

Local clock time : Sun Jan 15 20:57:29 2019

Clock source info:

Clock Pri1 Pri2 Accuracy Class TimeSrc Direction In-Status Offset(log variance)

-------------------------------------------------------------------

Local 128 128 254 248 160 N/A N/A 65535

ToD0 0 128 32 6 32 In Inactive 65535

ToD1 128 128 32 6 32 N/A Inactive 65535

# Display brief PTP running information for all PTP interfaces on Device A.

[DeviceA] display ptp interface brief

Name State Delay mechanism Clock step Asymmetry correction

GE1/2/0/1 Master E2E Two 0

# Display PTP clock information on Device B.

[DeviceB] display ptp clock

PTP profile : IEEE 1588 Version 2

PTP mode : E2ETC

Slave only : No

Sync uncertain : Disabled

Clock state : Disabled

Clock ID : 000FE2-FFFE-FF0001

Clock type : Local

Clock domain : 0

Number of PTP ports : 2

Priority1 : 128

Priority2 : 128

Clock quality :

Class : 248

Accuracy : 254

Offset (log variance) : 65535

Offset from master : N/A

Mean path delay : N/A

Steps removed : N/A

Local clock time : Sun Jan 15 20:57:29 2019

Clock source info:

Clock Pri1 Pri2 Accuracy Class TimeSrc Direction In-Status Offset(log variance)

-------------------------------------------------------------------

Local 128 128 254 248 160 N/A N/A 65535

ToD0 0 128 32 6 32 In Inactive 65535

ToD1 128 128 32 6 32 N/A Inactive 65535

# Display brief PTP running information for all PTP interfaces on Device B.

[DeviceB] display ptp interface brief

Name State Delay mechanism Clock step Asymmetry correction

GE1/2/0/1 N/A E2E Two 0

GE1/2/0/2 N/A E2E Two 0

The output shows that Device A is elected as the GM, and GigabitEthernet1/2/0/1 on Device A is the master port.

Example: Configuring PTP (IEEE 1588 version 2, IPv4 UDP transport, multicast transmission)

Network configuration

As shown in Figure 6, configure PTP (IEEE 1588 version 2, IPv4 UDP transport, multicast transmission) to enable time synchronization between the devices.

· Specify the IEEE 1588 version 2 PTP profile for Device A, Device B, and Device C.

· Use the IPv4 UDP transport protocol for PTP messages.

· Assign Device A, Device B, and Device C to the same PTP domain. Specify the OC clock node type for Device A and Device C, and P2PTC clock node type for Device B. All clock nodes elect a GM through BMC in the PTP domain.

· Specify the peer delay measurement mechanism (p2p) for Device A and Device C.

Figure 6 Network diagram

‌

Procedure

1. Configure Device A:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceA> system-view

[DeviceA] ptp profile 1588v2

# Specify the OC clock node type.

[DeviceA] ptp mode oc

# Configure the source IP address for multicast PTP messages transmitted over IPv4 UDP.

[DeviceA] ptp source 10.10.1.1

# Specify PTP for obtaining the time on the default MDC.

[DeviceA] clock protocol ptp mdc 1

# On GigabitEthernet 1/2/0/1, specify the IPv4 UDP transport protocol for PTP messages and the peer delay measurement mechanism (p2p), and enable PTP.

[DeviceA] interface gigabitethernet 1/2/0/1

[DeviceA-GigabitEthernet1/2/0/1] ptp transport-protocol udp [DeviceA-GigabitEthernet1/2/0/1] ptp delay-mechanism p2p

[DeviceA-GigabitEthernet1/2/0/1] ptp enable

[DeviceA-GigabitEthernet1/2/0/1] quit

2. Configure Device B:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceB> system-view

[DeviceB] ptp profile 1588v2

# Specify the P2PTC clock node type.

[DeviceB] ptp mode p2ptc

# Configure the source IP address for multicast PTP messages transmitted over IPv4 UDP.

[DeviceB] ptp source 10.10.2.1

# Specify PTP for obtaining the time on the default MDC.

[DeviceB] clock protocol ptp mdc 1

# On GigabitEthernet 1/2/0/1, specify the IPv4 UDP transport protocol for PTP messages and enable PTP.

[DeviceB] interface gigabitethernet 1/2/0/1

DeviceB-GigabitEthernet1/2/0/1] ptp transport-protocol udp

[DeviceB-GigabitEthernet1/2/0/1] ptp enable

[DeviceB-GigabitEthernet1/2/0/1] quit

# On GigabitEthernet 1/2/0/2, specify the IPv4 UDP transport protocol for PTP messages and enable PTP.

[DeviceB] interface gigabitethernet 1/2/0/2

[DeviceB-GigabitEthernet1/2/0/2] ptp transport-protocol udp

[DeviceB-GigabitEthernet1/2/0/2] ptp enable

[DeviceB-GigabitEthernet1/2/0/2] quit

3. Configure Device C:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceC> system-view

[DeviceC] ptp profile 1588v2

# Specify the OC clock node type.

[DeviceC] ptp mode oc

# Configure the source IP address for multicast PTP messages transmitted over IPv4 UDP.

[DeviceC] ptp source 10.10.3.1

# Specify PTP for obtaining the time on the default MDC.

[DeviceC] clock protocol ptp mdc 1

# On GigabitEthernet 1/2/0/1, specify the IPv4 UDP transport protocol for PTP messages and the peer delay measurement mechanism (p2p), and enable PTP.

[DeviceC] interface gigabitethernet 1/2/0/1

[DeviceC-GigabitEthernet1/2/0/1] ptp transport-protocol udp [DeviceC-GigabitEthernet1/2/0/1] ptp delay-mechanism p2p

[DeviceC-GigabitEthernet1/2/0/1] ptp enable

[DeviceC-GigabitEthernet1/2/0/1] quit

Verifying the configuration

When the network is stable, perform the following tasks on Device A and Device B.

· Use the display ptp clock command to display PTP clock information.

· Use the display ptp interface brief command to display brief PTP running information for all PTP interfaces.

# Display PTP clock information on Device A.

[DeviceA] display ptp clock

PTP profile : IEEE 1588 Version 2

PTP mode : OC

Slave only : No

Sync uncertain : Disabled

Clock state : Disabled

Clock ID : 000FE2-FFFE-FF0000

Clock type : Local

Clock domain : 0

Number of PTP ports : 1

Priority1 : 128

Priority2 : 128

Clock quality :

Class : 248

Accuracy : 254

Offset (log variance) : 65535

Offset from master : 0 (ns)

Mean path delay : 0 (ns)

Steps removed : 0

Local clock time : Sun Jan 15 20:57:29 2019

Clock source info:

Clock Pri1 Pri2 Accuracy Class TimeSrc Direction In-Status Offset(log variance)

-------------------------------------------------------------------

Local 128 128 254 248 160 N/A N/A 65535

ToD0 0 128 32 6 32 In Inactive 65535

ToD1 128 128 32 6 32 N/A Inactive 65535

# Display brief PTP running information for all PTP interfaces on Device A.

[DeviceA] display ptp interface brief

Name State Delay mechanism Clock step Asymmetry correction

GE1/2/0/1 Master P2P Two 0

# Display PTP clock information on Device B.

[DeviceB] display ptp clock

PTP profile : IEEE 1588 Version 2

PTP mode : P2PTC

Slave only : No

Sync uncertain : Disabled

Clock state : Disabled

Clock ID : 000FE2-FFFE-FF0001

Clock type : Local

Clock domain : 0

Number of PTP ports : 2

Priority1 : 128

Priority2 : 128

Clock quality :

Class : 248

Accuracy : 254

Offset (log variance) : 65535

Offset from master : N/A

Mean path delay : N/A

Steps removed : N/A

Local clock time : Sun Jan 15 20:57:29 2019

Clock source info:

Clock Pri1 Pri2 Accuracy Class TimeSrc Direction In-Status Offset(log variance)

-------------------------------------------------------------------

Local 128 128 254 248 160 N/A N/A 65535

ToD0 0 128 32 6 32 In Inactive 65535

ToD1 128 128 32 6 32 N/A Inactive 65535

# Display brief PTP running information for all PTP interfaces on Device B.

[DeviceB] display ptp interface brief

Name State Delay mechanism Clock step Asymmetry correction

GE1/2/0/1 N/A P2P Two 0

GE1/2/0/2 N/A P2P Two 0

The output shows that Device A is elected as the GM, and GigabitEthernet1/2/0/1 on Device A is the master port.

Example: Configuring PTP (IEEE 1588 version 2, IPv4 UDP transport, unicast transmission)

Network configuration

As shown in Figure 7, configure PTP (IEEE 1588 version 2, IPv4 UDP transport, unicast transmission) to enable Device A, Device B, Device C, and the base station to synchronize the time with the ToD clock source.

· Specify the IEEE 1588 version 2 PTP profile and unicast IPv4 UDP transport of PTP messages for Device A, Device B, and Device C.

· Assign Device A, Device B, Device C, and the base station to PTP domain 0. Specify the BC clock node type for Device A, Device B, and Device C.

· Connect Device A to the ToD clock source and Device C to the base station.

· Use the default Request_Response delay measurement mechanism on all clock nodes in the PTP domain.

Figure 7 Network diagram

‌

Procedure

1. Assign IP addresses to the interfaces, and make sure the devices can reach each other, as shown in Figure 7. (Details not shown.)

2. Configure Device A:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceA> system-view

[DeviceA] ptp profile 1588v2

# Specify the BC clock node type.

[DeviceA] ptp mode bc

# Configure the device to receive ToD clock signals and set the delay time correction value to 1000 nanoseconds.

[DeviceA] ptp tod0 input delay 1000

# Set priority 1 to 0 for the ToD 0 clock.

[DeviceA] ptp priority clock-source tod0 priority1 0

# On GigabitEthernet 1/2/0/1, configure the destination IP address for unicast PTP messages transmitted over IPv4 UDP, and enable PTP.

[DeviceA] interface gigabitethernet 1/2/0/1

[DeviceA-GigabitEthernet1/2/0/1] ptp transport-protocol udp

[DeviceA-GigabitEthernet1/2/0/1] ptp unicast-destination 10.10.10.2

[DeviceA-GigabitEthernet1/2/0/1] ptp enable

[DeviceA-GigabitEthernet1/2/0/1] quit

3. Configure Device B:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceB> system-view

[DeviceB] ptp profile 1588v2

# Specify the BC clock node type.

[DeviceB] ptp mode bc

# Specify PTP for obtaining the time on the default MDC.

[DeviceB] clock protocol ptp mdc 1

# On GigabitEthernet 1/2/0/1, configure the destination IP address for unicast PTP messages transmitted over IPv4 UDP, and enable PTP.

[DeviceB] interface gigabitethernet 1/2/0/1

[DeviceB-GigabitEthernet1/2/0/1] ptp transport-protocol udp

[DeviceB-GigabitEthernet1/2/0/1] ptp unicast-destination 10.10.10.1

[DeviceB-GigabitEthernet1/2/0/1] ptp enable

[DeviceB-GigabitEthernet1/2/0/1] quit

# On GigabitEthernet 1/2/0/2, configure the destination IP address for unicast PTP messages transmitted over IPv4 UDP, and enable PTP.

[DeviceB] interface gigabitethernet 1/2/0/2

[DeviceB-GigabitEthernet1/2/0/2] ptp transport-protocol udp

[DeviceB-GigabitEthernet1/2/0/2] ptp unicast-destination 11.10.10.1

[DeviceB-GigabitEthernet1/2/0/2] ptp enable

[DeviceB-GigabitEthernet1/2/0/2] quit

4. Configure Device C:

# Specify the IEEE 1588 version 2 PTP profile.

<DeviceC> system-view

[DeviceC] ptp profile 1588v2

# Specify the BC clock node type.

[DeviceC] ptp mode bc

# Configure the device to receive ToD clock signals and set the delay time correction value to 100 nanoseconds.

[DeviceC] ptp tod0 output delay 100

# Specify PTP for obtaining the time on the default MDC.

[DeviceC] clock protocol ptp mdc 1

# On GigabitEthernet 1/2/0/1, configure the destination IP address for unicast PTP messages transmitted over IPv4 UDP, and enable PTP.

[DeviceC] interface gigabitethernet 1/2/0/1

[DeviceC-GigabitEthernet1/2/0/1] ptp transport-protocol udp

[DeviceC-GigabitEthernet1/2/0/1] ptp unicast-destination 11.10.10.2

[DeviceC-GigabitEthernet1/2/0/1] ptp enable

[DeviceC-GigabitEthernet1/2/0/1] quit

# On GigabitEthernet 1/2/0/2, configure the destination IP address for unicast PTP messages transmitted over IPv4 UDP, and enable PTP.

[DeviceB] interface gigabitethernet 1/2/0/2

[DeviceB-GigabitEthernet1/2/0/2] ptp transport-protocol udp

[DeviceB-GigabitEthernet1/2/0/2] ptp unicast-destination 11.10.10.1

[DeviceB-GigabitEthernet1/2/0/2] ptp enable

[DeviceB-GigabitEthernet1/2/0/2] quit

5. Configure the base station.

# Specify PTP domain 0.

# Specify IPv4 UDP transport of PTP messages.

# Set the destination IP address of unicast PTP messages to 12.10.10.2.

# Specify the Request_Response delay measurement mechanism.

For more information, see the configuration guide for the base station.

Verifying the configuration

When the network is stable, perform the following tasks:

· Use the display ptp clock command to display PTP clock information.

· Use the display ptp interface brief command to display brief PTP running information for all PTP interfaces.

# Display PTP clock information on Device A.

[DeviceA] display ptp clock

PTP profile : IEEE 1588 Version 2

PTP mode : BC

Slave only : No

Sync uncertain : Disabled

Clock state : Disabled

Clock ID : 000FE2-FFFE-FF0000

Clock type : ToD0

ToD direction : In

ToD delay time : 1000 (ns)

Clock domain : 0

Number of PTP ports : 1

Priority1 : 0

Priority2 : 128

Clock quality :

Class : 6

Accuracy : 32

Offset (log variance) : 65535

Offset from master : 0 (ns)

Mean path delay : 0 (ns)

Steps removed : 0

Local clock time : Sun Jan 15 20:57:29 2019

Clock source info:

Clock Pri1 Pri2 Accuracy Class TimeSrc Direction In-Status Offset(log variance)

-------------------------------------------------------------------

Local 128 128 254 248 160 N/A N/A 65535

ToD0 128 128 32 6 32 In Active 65535

ToD1 128 128 32 6 32 N/A Inactive 65535

# Display brief PTP running information for all PTP interfaces on Device A.

[DeviceA] display ptp interface brief

Name State Delay mechanism Clock step Asymmetry correction

GE1/2/0/1 Master E2E Two 0

# Display PTP clock information on Device C.

[DeviceC] display ptp clock

PTP profile : IEEE 1588 Version 2

PTP mode : BC

Slave only : No

Sync uncertain : Disabled

Clock state : Disabled

Clock ID : 000FE2-FFFE-FF0001

Clock type : Local

Clock domain : 0

Number of PTP ports : 2

Priority1 : 128

Priority2 : 128

Clock quality :

Class : 248

Accuracy : 254

Offset (log variance) : 65535

Offset from master : 106368539000 (ns)

Mean path delay : 2791000 (ns)

Steps removed : 2

Local clock time : Sun Jan 15 20:57:29 2019

Clock source info:

Clock Pri1 Pri2 Accuracy Class TimeSrc Direction In-Status Offset(log variance)

-------------------------------------------------------------------

Local 128 128 254 248 160 N/A N/A 65535

ToD0 128 128 32 6 32 In Inactive 65535

ToD1 128 128 32 6 32 N/A Inactive 65535

# Display brief PTP running information for all PTP interfaces on Device C.

[DeviceC] display ptp interface brief

Name State Delay mechanism Clock step Asymmetry correction

GE1/2/0/1 N/A Slave Two 0

GE1/2/0/2 N/A Master Two 0

The output shows that Device A is elected as the GM, and GigabitEthernet1/2/0/1 on Device A is the master port.

Example: Configuring PTP (ITU-T G.8275.1, IEEE 802.3/Ethernet transport, multicast transmission)

Network configuration

As shown in Figure 8, configure PTP (ITU-T G.8275.1, IEEE 802.3/Ethernet transport, multicast transmission) to enable Device A to synchronize Device B.

· Specify the ITU-T G.8275.1 PTP profile for Device A and Device B.

· Assign Device A and Device B to the same PTP domain. Specify the T-BC clock node type for Device A and T-TSC clock node type for Device B.

· Use the default Request_Response delay measurement mechanism on Device A and Device B.

Figure 8 Network diagram

‌

Procedure

IMPORTANT:

The ITU-T G.8275.1 PTP profile transports PTP messages over IEEE 802.3/Ethernet rather than IPv4 UDP and in multicast rather than unicast mode.

1. Configure Device A:

# Specify the ITU-T G.8275.1 PTP profile.

<DeviceA> system-view

[DeviceA] ptp profile g8275.1

# Specify the T-BC clock node type.

[DeviceA] ptp mode t-bc

# Specify PTP for obtaining the time on the default MDC.

[DeviceA] clock protocol ptp mdc 1

# Enable PTP on GigabitEthernet 1/2/0/1.

[DeviceA] interface gigabitethernet 1/2/0/1

[DeviceA-GigabitEthernet1/2/0/1] ptp enable

[DeviceA-GigabitEthernet1/2/0/1] quit

2. Configure Device B:

# Specify the ITU-T G.8275.1 PTP profile.

<DeviceB> system-view

[DeviceB] ptp profile g8275.1

# Specify the T-TSC clock node type.

[DeviceB] ptp mode t-tsc

# Specify PTP for obtaining the time on the default MDC.

[DeviceB] clock protocol ptp mdc 1

# Enable PTP on GigabitEthernet 1/2/0/1.

[DeviceB] interface gigabitethernet 1/2/0/1

[DeviceB-GigabitEthernet1/2/0/1] ptp enable

[DeviceB-GigabitEthernet1/2/0/1] quit

Verifying the configuration

When the network is stable, perform the following tasks:

· Use the display ptp clock command to display PTP clock information.

· Use the display ptp interface brief command to display brief PTP running information for all PTP interfaces.

# Display PTP clock information on Device A.

[DeviceA] display ptp clock

PTP profile : ITU-T G.8275.1

PTP mode : T-BC

Slave only : No

Sync uncertain : Disabled

Clock state : Disabled

Clock ID : 24881D-FFFE-F20100

Clock type : Local

Clock domain : 24

Number of PTP ports : 1

Priority1 : 128

Priority2 : 128

Local priority : 128

Clock quality :

Class : 248

Accuracy : 254

Offset (log variance) : 65535

Offset from master : 0 (ns)

Mean path delay : 0 (ns)

Steps removed : 0

Local clock time : Fri Dec 7 00:59:44 2018

Clock source info:

Clock LP Pri2 Accuracy Class TimeSrc Direction In-Status Offset(log variance)

-------------------------------------------------------------------

Local 128 128 254 248 160 N/A N/A 65535

ToD0 128 128 32 6 32 N/A Inactive 65535

ToD1 128 128 32 6 32 N/A Inactive 65535

# Display brief PTP running information for all PTP interfaces on Device A.

[DeviceA] display ptp interface brief

Name State Delay mechanism Clock step Asymmetry correction

GE1/2/0/1 Master E2E Two 0

# Display PTP clock information on Device B.

[DeviceB] display ptp clock

PTP profile : ITU-T G.8275.1

PTP mode : T-TSC

Slave only : No

Sync uncertain : Disabled

Clock state : Disabled

Clock ID : 2461E3-FFFE-A20200

Clock type : Local

Clock domain : 24

Number of PTP ports : 1

Priority1 : 128

Priority2 : 255

Local priority : 128

Clock quality :

Class : 255

Accuracy : 254

Offset (log variance) : 65535

Offset from master : 49915149500000 (ns)

Mean path delay : 500000 (ns)

Steps removed : 1

Local clock time : Fri Dec 7 14:52:54 2018

Clock source info:

Clock LP Pri2 Accuracy Class TimeSrc Direction In-Status Offset(log variance)

-------------------------------------------------------------------

Local 128 255 254 255 160 N/A N/A 65535

ToD0 128 255 254 255 32 N/A Inactive 65535

ToD1 128 255 254 255 32 N/A Inactive 65535

# Display brief PTP running information for all PTP interfaces on Device B.

[DeviceB] display ptp interface brief

Name State Delay mechanism Clock step Asymmetry correction

GE1/2/0/1 Slave E2E Two 0

The output shows that Device A is elected as the GM, and GigabitEthernet1/2/0/1 on Device A is the master port.

14-Network Management and Monitoring Configuration Guide

Basic concepts

PTP profile

PTP domain

Clock node and PTP port

Clock node and PTP port (ITU-T G.8275.1)

Master-member/subordinate relationship

Clock source type

Grandmaster clock

ITU-T G.8275.1

Request_Response

Peer Delay

Specifying PTP for obtaining the time

Specifying a PTP profile

Restrictions and guidelines

Procedure

Restrictions and guidelines

Procedure

Configuring an OC to operate only as a member clock

About this task

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Procedure

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Configuring PTP message transmission and receiving

Setting the interval for sending announce messages and the timeout multiplier for receiving announce messages

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Configuring a source IP address for multicast PTP messages transmitted over IPv4 UDP

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Restrictions and guidelines

Procedure

Configuring a destination IP address for unicast PTP messages transmitted over IPv4 UDP

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Restrictions and guidelines

Prerequisites

Procedure

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Procedure

Setting a DSCP value for PTP messages transmitted over UDP

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