Contents

Configuring PTP· 1

Overview· 1

Basic concepts· 1

Synchronization mechanism·· 3

Protocols and standards· 5

Configuring clock nodes· 5

Configuration task list 5

Specifying a PTP standard· 6

Specifying a clock node type· 7

Specifying a PTP domain· 7

Configuring an OC to operate only as a member clock· 7

Configuring the role of a PTP port 8

Configuring the mode for carrying timestamps· 8

Specifying a delay measurement mechanism for a BC or an OC· 9

Configuring the port type for a TC+OC· 9

Setting the interval for sending announce messages· 9

Specifying the number of announcement intervals before the receiving node stops receiving announce messages  10

Setting the interval for sending Pdelay_Req messages· 10

Setting the interval for sending Sync messages· 10

Setting the minimum interval for sending Delay_Req messages· 11

Configuring the MAC address for non-pdelay messages· 11

Specifying the protocol for encapsulating PTP messages as UDP (IPv4) 11

Specifying the source IP address for UDP packets· 12

Setting the delay correction value· 12

Setting the cumulative offset between the UTC and TAI 12

Setting the correction date of the UTC· 13

Configuring the parameters of the BITS clock· 13

Configuring a priority of the clock· 13

Specifying the system time source as PTP· 14

Enabling PTP on a port 14

Displaying and maintaining PTP· 14

PTP configuration examples· 15

PTP configuration example (IEEE 1588 version 2) 15

PTP configuration example (IEEE 802.1AS) 17

 

Configuring PTP

Overview

Precision Time Protocol (PTP) synchronizes time among devices. It provides greater accuracy than other time synchronization protocols such as NTP. It can also be used for frequency synchronization. For more information about NTP, see "Configuring NTP."

Basic concepts

PTP profile

A PTP profile defines two PTP standards: IEEE 1588 version 2 and IEEE 802.1AS.

·           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.

·           IEEE 802.1AS—802.1AS is introduced based on IEEE 1588. It specifies a profile for use of IEEE 1588-2008 for time synchronization over a virtual bridged local area network (as defined by IEEE 802.1Q). The BMC algorithm in 802.1AS supports only the peer delay mode, and point-to-point full-duplex Ethernet, IEEE 802.11, and IEEE 802.3 EPON links.

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 a clock node. A port enabled with PTP is a PTP port. PTP defines the following three 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 a clock node works as the clock source and sends synchronization time through a single PTP port to its downstream clock node, it is also called an OC.

·           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, and uses the other ports to synchronize time to the relevant upstream clock nodes. If a clock node works as the clock source and synchronizes time through multiple PTP ports to its downstream clock nodes, it is also called a BC, such as BC 1 in Figure 1.

·           Transparent Clock (TC)—A TC does not need to keep time consistency with other clock nodes. A TC has multiple PTP ports. It only 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 packets 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 three types of clock nodes in a PTP domain.

Figure 1 Clock nodes in a PTP domain

 

Besides the three basic types of clock nodes, PTP introduces some 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.

Master-member/subordinate relationship

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, and that on a member node is a member clock.

·           Master/Subordinate 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 time is a passive port.

Grandmaster clock

In Figure 1, all clock nodes are organized together and ultimately derive their time from a clock known as the "grandmaster clock (GM)." The GM clock source synchronizes its time to the entire PTP domain through PTP messages exchanged among the clock nodes.

A GM can be manually configured, or it can be elected through the Best Master Clock (BMC) algorithm as follows:

1.      By exchanging announce messages containing the priorities, time class, and time accuracy of GMs, clock nodes in a PTP domain elect a GM. The master nodes, member nodes, master ports, and subordinate ports are specified during the process. Then a loop-free, interconnected spanning tree with the GM as the root is generated for the PTP domain.

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

Clock source type

A clock node of a device can use one of the following clock sources: local clock source and BITS clock source (BITS1 and BITS2) that connects the device.

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

·           BITS clock—Clock signals generated by a BITS clock device. The signals are sent to the clock monitoring module through a specific interface on the device and then sent to all member devices by the clock monitoring module.

The clock node determines to use which type of clock source based on the specified algorithm.

Synchronization mechanism

Based on the exchanged synchronization messages, a member node calculates the round-trip delay of the path to the master node. The one-way delay equals half of the round-trip delay (assume the delays in both directions are the same). Then the member node synchronizes its clock with the master clock according to the offset between the clocks.

PTP defines the following transmission delay measurement mechanisms:

·           Request_Response.

·           Peer Delay.

The basis of the two mechanisms is that the transmission delay from the master clock to the member clock is the same as that from the member clock to the master clock.

Request_Response

Figure 2 Operation procedure of the Request_Response mechanism

 

Figure 2 shows the operation procedure of the Request_Response mechanism, which applies only to peer-to-peer delay measurement. It shows an example of 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 carrying time t1.

3.      The member clock sends a Delay_Req message to calculate the transmission delay in the reverse direction, 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 carrying time t4.

From the above process, the member clock collects four timestamps, t1 to t4, and obtains the round-trip delay to the master clock by using the following calculation:

·           [(t2 – t1) + (t4 – t3)]

The member clock also obtains the one-way delay by using the following calculation:

·           [(t2 – t1) + (t4 – t3)] / 2

The offset between the member and master clocks is obtained by using the following calculation:

·           (t2 – t1) – [(t2 – t1) + (t4 – t3)] / 2

·           [(t2 – t1) – (t4 – t3)] / 2

Depending on whether to send Follow_Up messages, the Request_Response mechanism includes two modes: single-step and two-step.

·           In single-step mode, t1 is carried in the Sync message, and no Follow_Up message is sent.

·           In two-step mode, t1 is carried in the Follow_Up message.

Peer Delay

Figure 3 Operation procedure of the Peer Delay mechanism

 

The Peer Delay mechanism uses Pdelay messages to calculate link delay, which applies only to point-to-point delay measurement. Figure 3 shows an example of the Peer Delay mechanism by using the 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 sends a Follow_Up message carrying time t1 immediately.

3.      The member clock sends a Pdelay_Req message to calculate the transmission delay in the reverse direction, and records the sending time t3. Upon receiving the message, the master clock records the receiving time t4.

4.      The master clock returns a Pdelay_Resp message carrying time t4, and records the sending time t5. Upon receiving the message, the member clock records the receiving time t6.

5.      After sending the Pdelay_Resp message, the master clock sends a Pdelay_Resp_Follow_Up message carrying time t5 immediately.

From the above process, the member clock collects six timestamps, t1 to t6, and obtains the round-trip delay to the master clock by using the following calculation:

·           [(t4 – t3) + (t6 – t5)]

The member clock also obtains the one-way delay by using the following calculation:

·           [(t4 – t3) + (t6 – t5)] / 2

The offset between the member and master clocks is as follows:

·           (t2 – t1) – [(t4 – t3) + (t6 – t5)] / 2

Depending on whether to send Follow_Up messages, the Peer Delay mechanism includes two modes: single-step and two-step.

·           In single-step mode, t1 is carried in the Sync message, and no Follow_Up message is sent. The offset between t5 and t4 is carried in the Pdelay_Resp message, and no Pdelay_Resp_Follow_Up message is sent.

·           In two-step mode, t1 is carried in the Follow_Up message, and t4 and t5 are carried in the Pdelay_Resp and Pdelay_Resp_Follow_Up messages.

Protocols and standards

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

·           IEEE P802.1AS, Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks

Configuring clock nodes

Before performing the following configurations, define the scope of the PTP domain and the role of every clock node.

Configuration task list

Tasks at a glance
(Required.) Specifying a PTP standard
The PTP standard is IEEE 1588 version 2: (Required.) Specifying a clock node type (Optional.) Specifying a PTP domain (Optional.) Configuring an OC to operate only as a member clock (Optional.) Configuring the role of a PTP port (Optional.) Configuring the mode for carrying timestamps (Optional.) Specifying a delay measurement mechanism for a BC or an OC (Optional.) Configuring the port type for a TC+OC (Optional.) Setting the interval for sending announce messages (Optional.) Setting the interval for sending Pdelay_Req messages (Optional.) Setting the interval for sending Sync messages (Optional.) Setting the minimum interval for sending Delay_Req messages (Optional.) Configuring the MAC address for non-pdelay messages (Optional.) Specifying the protocol for encapsulating PTP messages as UDP (IPv4) (Optional.) Specifying the source IP address for UDP packets (Optional.) Setting the delay correction value (Optional.) Setting the cumulative offset between the UTC and TAI (Optional.) Setting the correction date of the UTC (Optional.) Configuring the parameters of the BITS clock (Optional.) Configuring a priority of the clock (Optional.) Specifying the system time source as PTP (Required.) Enabling PTP on a port
The PTP standard is IEEE 802.1AS (802.1AS): (Required.) Specifying a clock node type (Optional.) Specifying a PTP domain (Optional.) Configuring an OC to operate only as a member clock (Optional.) Configuring the role of a PTP port (Optional.) Configuring the port type for a TC+OC (Optional.) Setting the interval for sending announce messages (Optional.) Setting the interval for sending Pdelay_Req messages (Optional.) Setting the interval for sending Sync messages (Optional.) Setting the minimum interval for sending Delay_Req messages (Optional.) Setting the delay correction value (Optional.) Setting the cumulative offset between the UTC and TAI (Optional.) Setting the correction date of the UTC (Optional.) Configuring the parameters of the BITS clock (Optional.) Configuring a priority of the clock (Optional.) Specifying the system time source as PTP (Required.) Enabling PTP on a port

 

Specifying a PTP standard

Before configuring PTP, specify a PTP standard first. Otherwise, PTP cannot operate. Changing the PTP standard for the device clears all PTP configurations defined by the standard.

To specify a PTP standard:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Specify a PTP standard.	ptp profile { 1588v2 | 8021as }	By default, no PTP standard is configured, and PTP is not running on the device.

 

Specifying a clock node type

You can configure only one of the following six types of clock nodes for a device: OC, BC, E2ETC, P2PTC, E2ETC+OC, or P2PTC+OC.

Follow these guidelines when you specify the clock node type:

·           Before specifying the clock node type, specify a PTP standard first.

·           If the PTP standard is IEEE 802.1AS, the clock node type cannot be E2ETC or E2ETC+OC.

·           Changing the clock node type clears all PTP configurations except the PTP standard.

To specify the clock node type:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Specify the clock node type for the device.	ptp mode { bc | e2etc | e2etc-oc | oc | p2ptc | p2ptc-oc }	By default, no clock node type is specified.

 

Specifying a PTP domain

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

To specify a PTP domain:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Specify a PTP domain for the device.	ptp domain value	By default, PTP devices are in PTP domain 0.

 

Configuring an OC to operate only as a member clock

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

This task is applicable only to OCs.

This configuration is automatically cleared after you change the clock node type for the device.

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

To configure an OC to operate as only a member clock:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Configure the OC to operate as only a member clock.	ptp slave-only	By default, the OC is not configured to operate as only a member clock.

 

Configuring the role of a PTP port

Typically the master/member relationships are automatically specified through BMC. This task allows you to manually configure the master/member relationships among clock nodes. The ptp force-state command is available only after you configure the ptp active force-state command.

Follow these guidelines when you configure the role of a PTP port:

·           Only one subordinate port is allowed to be configured for a device.

·           This task is also applicable to an OC that operates in slave-only mode.

To configure the PTP port role on an OC, BC, E2ETC+OC, or P2PTC+OC:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Configure the role of the PTP port.	ptp force-state { master | passive | slave }	By default, the PTP port role is automatically specified through BMC.
4.      Quit interface view.	quit	N/A
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

Timestamps can be carried in either of the following two modes:

·           Single-step mode—In single-step mode, the Sync message in the Request_Response and Peer Delay mechanisms and the Pdelay_Resp message in the Peer Delay mechanism carry the sending time of the messages.

·           Two-step mode—In two-step mode, the Sync message in the Request_Response and Peer Delay mechanisms and the Pdelay_Resp message in the Peer Delay mechanism do not carry the sending time of the messages. The sending time is carried in other messages.

To configure the mode for carrying timestamps for every clock node:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Configure the mode for carrying timestamps.	ptp clock-step { one-step | two-step }	By default, two-step mode is adopted.

 

Specifying a delay measurement mechanism for a BC or an OC

PTP defines two transmission delay measurement mechanisms: Request_Response and Peer Delay. Ports on the same link must share the same delay measurement mechanism. Otherwise, they cannot communicate with one another. BCs and OCs do not have a default delay measurement mechanism. You must specify a delay measurement mechanism for them. The delay measurement mechanism of E2ETCs and E2ETC+OCs is Request_Response, and that of P2PTCs and P2PTC+OCs is Peer Delay. You cannot change these defaults.

This task is applicable only to BCs and OCs.

If the PTP standard is IEEE 802.1AS, only Peer Delay mode is supported.

To specify a delay measurement mechanism for a BC or OC:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Specify a delay measurement mechanism for a BC or OC.	ptp delay-mechanism { e2e | p2p }	By default, the delay measurement mechanism depends on the PTP standard.

 

Configuring the port type for a TC+OC

All ports on a TC+OC (E2ETC+OC or P2PTC+OC) are TCs by default. This command allows you to configure one of the ports as an OC. This task is applicable only to E2ETC+OCs and P2PTC+OCs.

When a TC+OC is synchronizing time to a downstream clock node through a TC, do not enable an OC to synchronize time from the downstream clock node. Otherwise, time synchronization might be affected.

To configure the port type for a TC+OC as OC:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Configure the port type for a TC+OC as OC.	ptp port-mode oc	By default, the type of all ports on a TC+OC is TC.

 

Setting the interval for sending announce messages

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Set the interval for sending announce messages.	ptp announce-interval value	By default: ·          The interval is 2 (21) seconds if the PTP standard is IEEE 1588 version 2. ·          The interval is 1 (20) second if the PTP standard is IEEE 802.1AS.

 

Specifying the number of announcement intervals before the receiving node stops receiving announce messages

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 the specified interval, it considers the master node invalid.

If the PTP standard is IEEE 1588 version 2, the interval is the announce message sending interval × multiple-value. If the PTP standard is IEEE 802.1AS, the interval is the announce message sending interval for the master node × multiple-value.

To specify the number of announcement intervals before the receiving node stops receiving announce messages:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Specify the number of announcement intervals before the receiving node stops receiving announce messages.	ptp announce-timeout multiple-value	The default is 3.

 

Setting the interval for sending Pdelay_Req messages

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Set the interval for sending Pdelay_Req messages.	ptp pdelay-req-interval value	Optional. The default is 1 (20) second.

 

Setting the interval for sending Sync messages

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Set the interval for sending Sync messages.	ptp syn-interval value	By default: ·          The interval is 1 (20) second if the PTP standard is IEEE 1588 version 2. ·          The interval is 1/8 (2-3) seconds if the PTP standard is IEEE 802.1AS.

 

Setting the minimum interval for sending Delay_Req messages

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Set the minimum interval for sending Delay_Req messages.	ptp min-delayreq-interval value	The default is 1 (20) second. When receiving a Sync or Follow_Up message, an interface can send Delay_Req messages only when the minimum interval is reached.

 

Configuring the MAC address for non-pdelay messages

Pdelay messages include Pdelay_Req, Pdelay_Resp, and Pdelay_Resp_Follow_Up messages. The destination MAC address of Pdelay messages is 0180-C200-000E by default, which cannot be modified. The destination MAC address of non-Pdelay messages is either 0180-C200-000E or 011B-1900-0000.

If ports on the same link forward PTP packets of the same type to different destination MAC addresses, they do not receive the packets from each other. You need to configure the same destination MAC address for the ports.

To configure the destination MAC address for non-Pdelay messages on every clock node:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Configure the destination MAC address for non-Pdelay messages.	ptp destination-mac mac-address	The default is 011B-1900-0000.

 

Specifying the protocol for encapsulating PTP messages as UDP (IPv4)

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

To configure the protocol for encapsulating PTP messages as UDP (IPv4):

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Configure the protocol for encapsulating PTP messages as UDP (IPv4).	ptp transport-protocol udp	By default, PTP messages are encapsulated in IEEE 802.3/Ethernet packets.

 

Specifying the source IP address for UDP packets

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter interface view.	ptp source ip-address [ vpn-instance vpn-instance-name ]	By default, no source IP address is specified for PTP messages encapsulated in UDP packets.

 

Setting the delay correction value

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 configure the delay correction value for more accurate time synchronization.

To configure the delay correction value for every clock node:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Set delay correction value.	ptp asym-correction { minus | plus } value	Optional. The default is 0 nanoseconds, which means delay correction is not performed.

 

Setting the cumulative offset between the UTC and TAI

The time displayed on a device is based on the Coordinated Universal Time (UTC). There is an offset between UTC and TAI (International Atomic Time in English), which is made public periodically. This task allows you to adjust the offset between the UTC and TAI on the device. It is applicable only to the GM.

To set the cumulative offset between the UTC and TAI:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
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

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

To set the correction date of the UTC:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
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. This command takes effect only on the GM.

 

Configuring the parameters of the BITS clock

Clock nodes in a PTP domain exchange announce messages through BMC to elect a GM. They compare the parameters in the announce messages in the following sequence: priority 1, time class, time accuracy, and priority 2. If all these parameters are the same, the clock node with a smaller port ID (consisting of clock number and port number) wins.

To configure the clock parameters

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Configure priority 1 of the clock.	ptp priority clock-source { bits1 | bits2 | local } priority1 pri1-value	Optional. The default is 128.
3.      Configure the parameters of the BITS clock.	ptp clock-source { bits1 | bits2 } { accuracy acc-value | class class-value | time-source ts-value }	By default, the time accuracy is 254, the time class is 248, and the attribute value is 160 for the BITS clock.
4.      Configure the time accuracy of the BITS clock.	ptp clock-source { bits1 | bits2 } accuracy acc-value	Optional. The default is 254.
5.      Configure priority 2 of the clock.	ptp priority clock-source { bits1 | bits2 | local } priority2 pri2-value	Optional. The default is 128.
6.      Configure the attribute value of the BITS clock.	ptp clock-source { bits1 | bits2 } time-source ts-value	Optional. The default is 160.

 

Configuring a priority of the clock

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Configure priority 1 of the clock.	ptp priority clock-source { bits1 | bits2 | local } { priority1 pri1-value | priority2 pri2-value }	By default: ·          If the PTP profile is IEEE 1588 version 2, the default value for both priority 1 and priority 2 is 128. ·          If the PTP profile is IEEE 802.1AS, the default value is 246 for priority 1 and 248 for priority 2.

 

Specifying the system time source as PTP

Before the configuration, make sure you use the clock protocol command to specify the time protocol as PTP. For more information about the clock protocol command, see Fundamentals Command Reference.

To specify the system time source as PTP:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Specify the system time source as PTP.	clock protocol ptp	By default, the system time source is NTP.

 

Enabling PTP on a port

A port enabled with PTP becomes a PTP port.

An OC can have only one PTP port.

To enable PTP on a port:

 

Step	Command	Remarks
1.      Enter system view.	system-view	N/A
2.      Enter Layer 2 Ethernet interface view.	interface interface-type interface-number	N/A
3.      Enabling PTP on the port.	ptp enable	By default, PTP is disabled on a port.

 

Displaying and maintaining 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 PTP statistics.	display ptp [ brief | interface interface-type interface-number ] [ | { begin | exclude | include } regular-expression ]
Display PTP clock time properties.	display ptp time-property
Clear PTP statistics.	reset ptp statistics [ interface interface-type interface-number ]

 

PTP configuration examples

PTP configuration example (IEEE 1588 version 2)

Network requirements

As shown in Figure 4, a PTP domain comprises Device A, Device B, and Device C.

·           Configure all devices to use PTP standard IEEE 1588 version 2.

·           Configure the clock node type of Device A and Device C as OC, and that of Device B as P2PTC. All clock nodes elect a GM through BMC based on their respective default GM attributes.

·           Configure the delay measurement mechanism for Device A and Device C as p2p.

Figure 4 Network diagram

 

Configuration procedure

1.      Configure Device A:

# Specify the PTP standard as IEEE 1588 version 2.

<DeviceA> system-view

[DeviceA] ptp profile 1588v2

# Specify the clock node type as OC.

[DeviceA] ptp mode oc

# On Ten-GigabitEthernet 1/0/1, specify the delay measurement mechanism as p2p, and enable PTP.

[DeviceA] interface ten-gigabitethernet 1/0/1

[DeviceA-Ten-GigabitEthernet1/0/1] ptp delay-mechanism p2p

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

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

2.      Configure Device B:

# Specify the PTP standard as IEEE 1588 version 2.

<DeviceB> system-view

[DeviceB] ptp profile 1588v2

# Specify the clock node type as P2PTC.

[DeviceB] ptp mode p2ptc

# Enable PTP for Ten-GigabitEthernet 1/0/1.

[DeviceB] interface ten-gigabitethernet 1/0/1

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

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

# Enable PTP for Ten-GigabitEthernet 1/0/2.

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

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

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

3.      Configure Device C:

# Specify the PTP standard as IEEE 1588 version 2.

<DeviceC> system-view

[DeviceC] ptp profile 1588v2

# Specify the clock node type as OC.

[DeviceC] ptp mode oc

# On Ten-GigabitEthernet 1/0/1, specify the delay measurement mechanism as p2p, and enable PTP.

[DeviceC] interface ten-gigabitethernet 1/0/1

[DeviceC-Ten-GigabitEthernet1/0/1] ptp delay-mechanism p2p

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

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

4.      Verify the configuration:

# Display PTP clock information on Device A.

[DeviceA] display ptp clock

PTP profile         : IEEE 1588 Version 2

PTP mode            : OC

Slave only          : No

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 2011

# Display brief PTP statistics on Device A.

[DeviceA] display ptp interface brief

Name         State         Delay mechanism  Clock step  Asymmetry correction

XGE1/0/1       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

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 2011

# Display brief PTP statistics on Device B.

[DeviceB] display ptp interface brief

Name         State         Delay mechanism  Clock step  Asymmetry correction

XGE1/0/1       N/A           P2P              Two         0

XGE1/0/2       N/A           P2P              Two         0

PTP configuration example (IEEE 802.1AS)

Network requirements

As shown in Figure 4, a PTP domain comprises Device A, Device B, and Device C.

·           Configure all devices to use PTP standard IEEE 802.1AS.

·           Configure the clock node type of Device A and Device C as OC, and that of Device B as P2PTC. All clock nodes elect a GM through BMC based on their respective default GM attributes.

·           Configure the delay measurement mechanism for Device A and Device C as p2p.

Figure 5 Network diagram

 

Configuration procedure

1.      Configure Device A:

# Specify the PTP standard as IEEE 802.1AS.

<DeviceA> system-view

[DeviceA] ptp profile 802.1AS

# Specify the clock node type as OC.

[DeviceA] ptp mode oc

# Enable PTP on Ten-GigabitEthernet 1/0/1.

[DeviceA] interface ten-gigabitethernet 1/0/1

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

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

2.      Configure Device B:

# Specify the PTP standard as IEEE 802.1AS.

<DeviceB> system-view

[DeviceB] ptp profile 802.1AS

# Specify the clock node type as P2PTC.

[DeviceB] ptp mode p2ptc

# Enable PTP for Ten-GigabitEthernet 1/0/1.

[DeviceB] interface ten-gigabitethernet 1/0/1

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

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

# Enable PTP for Ten-GigabitEthernet 1/0/2.

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

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

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

3.      Configure Device C:

# Specify the PTP standard as IEEE 1588 802.1AS.

<DeviceC> system-view

[DeviceC] ptp profile 802.1AS

# Specify the clock node type as OC.

[DeviceC] ptp mode oc

# Enable PTP on Ten-GigabitEthernet 1/0/1.

[DeviceC] interface ten-gigabitethernet 1/0/1

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

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

4.      Verify 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 statistics on an interface.

# Display PTP clock information on Device A.

[DeviceA] display ptp clock

PTP profile         : IEEE 802.1AS

PTP mode            : OC

Slave only          : No

Clock ID            : 000FE2-FFFE-FF0000

Clock type          : Local

Clock domain        : 0

Number of PTP ports : 1

Priority1     : 246

Priority2     : 248

Clock quality :

 Class                 : 248

 Accuracy              : 254

 Offset (log variance) : 16640

Offset from master : 0 (ns)

Mean path delay    : 0 (ns)

Steps removed      : 0

Local clock time   : Sun Jan 15 20:57:29 2011

# Display brief PTP statistics on Device A.

[DeviceA] display ptp interface brief

Name         State         Delay mechanism  Clock step  Asymmetry correction

XGE1/0/1       Master        P2P              Two         0

# Display PTP clock information on Device B.

[DeviceB] display ptp clock

PTP profile         : IEEE 802.1AS

PTP mode            : P2PTC

Slave only          : No

Clock ID            : 000FE2-FFFE-FF0001

Clock type          : Local

Clock domain        : 0

Number of PTP ports : 2

Priority1     : 246

Priority2     : 248

Clock quality :

 Class                 : 248

 Accuracy              : 254

 Offset (log variance) : 16640

Offset from master : N/A

Mean path delay    : N/A

Steps removed      : N/A

Local clock time   : Sun Jan 15 20:57:29 2011

# Display brief PTP statistics on Device B.

[DeviceB] display ptp interface brief

Name         State         Delay mechanism  Clock step  Asymmetry correction

XGE1/0/1       N/A           P2P              Two         0

XGE1/0/2       N/A           P2P              Two         0