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Page 1: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

PTN Synchronization Subject

V1.0

Page 2: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Contents

Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization and

Frequency Synchronization Communication Network Requirements for

Synchronization How to Achieve Synchronization Technology ZXCTN Series Device Synchronization

Function Synchronization Configuration Instance

Page 3: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Basic Concepts of Synchronization

SynchronizationSynchronization

Frequency Synchronization (FS)

Frequency Synchronization (FS)

Time Synchronization (TS)

Time Synchronization (TS)

Page 4: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Basic Concepts of Synchronization Frequency synchronization (FS)

FS refers to clock synchronization. It indicates that the frequencies or phases between signals are kept

in a strict relation. Its corresponding instant appears at the same and equal rate to keep all devices in the communication network running at the same rate.

Background information: The PCM (Pulse Code Modulation) discrete pulse which is obtained by encoding the information, is transmitted in the digital communication network. If the clock frequency between two digital switching devices are inconsistent, or the phase drift or jitter is overlapped because the digital bit stream is interfered and damaged in transmission, the element loss or repetition occurs in the buffer of the digital switching system, which causes the slide damage in the transmitted bit stream.

For more details, refer to the ITU-T G.8261/8262 standards approved in June, 2007.

Page 5: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Basic Concepts of Synchronization Phase synchronization (PS) (time

synchronization) It means that not only the frequency between signals should be

the same, but also the phase should be the same, so the time sychronization generally includes the clock synchronization. For more details, refer to the IEEE 1588V2 protocol.

To synchronize time is to modulate the internal clock and time of the device according to the received time. The modulation principle of the time synchronization is similar to that of the frequency synchronization on clock. Both the clock frequency and the clock phase should be modulated. Meanwhile, the clock phase is indicated as a value, namely time.

The differences from the FS are that the TS receives the non-consecutive time information and non-consecutively modulates the device clock, that the modulation of the device clock phase-lock loop is periodical; and that a clock in the TS can be a virutal clock.

Page 6: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Contents

Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization and

Frequency Synchronization Communication Network Requirements for

Synchronization How to Achieve Synchronization Technology ZXCTN Series Device Synchronization

Function Synchronization Configuration Instance

Page 7: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Difference between Time Synchronization and Frequency Synchronization

The above figure provides the differences between TS and FS. If every minute on Watch 1 and Watch 2 are inconsistent, the status is called

the TS. If the time on both watches is different, however, a constant difference is

kept, such as 1 hour, this status is called the FS. If the frequencies on both watches are different, their time values are not in a

fixed relation. Therefore, the prerequisite of the TS is the FS.

Counter

10 30:

Counter

10 30:

Frq1 Frq2

T 1 T 2

Watch11 Watch 2

Counter

10 30:

Counter

11 30:

Frq1 Frq2

T 1 T 2

Watch1 Watch 2

TS FS

Page 8: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Contents

Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization and

Frequency Synchronization Communication Network Requirements for

Synchronization How to Achieve Synchronization Technology ZXCTN Series Device Synchronization

Function Synchronization Configuration Instance

Page 9: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Communication Network Requirements for Synchronization

Traditional fixed network TDM service requirements for clock synchronization The TDM service of the traditional fixed network is

primarily voice service which requires a synchronization on both ends of service sending and receiving.

If the clocks on both ends of the bearer network are inconsistent, the slide code may occur after a long-term accumulation.

The ITUT defines the requirements and test standards, called the TRAFFIC Interface Standard, on the fixed network TDM service in G.823.

Page 10: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Communication Network Requirements for Synchronization

Radio IP RAN requirements on synchronization Currently, the TS is primarily applied in Call Charging, Inter-Network

Account Settling, and NM Alarm. The strictest requirement that the communication network has on the clock frequency is embodied on the wireless application. Frequencies on different BSs must be synchronized in a certain precision, otherwise, disconnection may occurs during the BS switchover. Different from the fixed network TDM application previously mentioned, the clock here refers to the RF clock. In this application scenario, the requirment for the clock frequency is higher than the former one.

Currently, the wireless technology exists in various forms. Requirements for clock bearing in different forms are much different.

Wireless technology Precision requirement for clock frequency TS requirement

GSM 0.05ppm NA

WCDMA 0.05ppm NA

CDMA2000 0.05ppm 3us

TD-SCDMA 0.05ppm 1.5us

WiMax 0.05ppm 1us

LTE 0.05ppm Tends to adopt TS

Page 11: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Communication Network Requirements for Synchronization Dedicated Clock Synchronization Network

Demands In the traditional communication network structure,

besides the service bearer network, generally, an independent clock release network also exist, adopting PDH/SDH to distribute the clock.

The ITU-T defines that, in this application scenario, the TIMING interface index in G.823 should be met.

Page 12: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Contents

Introduction to Synchronization Principle How to Achieve Synchronization

Technology SyncEthernet Technology TOP technology IEEE1588V2 ( PTP )

ZXCTN Series Device Synchronization Function

Synchronization Configuration Instance

Page 13: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Synchronized Ethernet (SyncE) technology uses Ethernet link code stream to restore clock.

At the physical layer, the Ethernet adopts the serial code stream mode for transmission, just like SDH.

4B/5B (FE) and 8B/10B (GE) are adopted in coding. Every 4 bits is inserted an additional bit. In this way, no four consecutive 1s or 0s occur in the transmitted data bit stream, which can effectively include the clock information.

Use highly precise clock to send data on Ethernet source port, restore and extract this clock at receiving end to keep accurate clock performance.

SyncEthernet Technology

Page 14: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

SyncEthernet Technology

SyncE Principle Diagram

Mast Clock

Slave Clock

Ethernet

TDM device

E1 TDM device

TDM device

E1

TDM device

BA

Transmit Receive

Line extraction clock

System cl ock

External cl ock

1G/10GPHY

High Precision

ClockPHY MAC

PLL

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Synchronous Ethernet The physical layer guarantees the clock performance of the SyncE,

and has nothing to do with the load and packet-forwarding delay on the Ethernet link layer. The procedure to achieve this function is as follows:

Devices, such as BITS, transmit the clock signal to the NE through the outer clock interface.

The clock signal is transmitted between NEs through the SyncE. The NE clock processing module extracts the Ethernet link clock from

the Ethernet port and selects the clock source. The system clock unit performs the clock locking and generates the

system clock. The system clock unit provides the Etherenet port that supports the

synchronization clock transmission, with the clock source used to transmit the clock to the downstream node when the Ethernet physical layer sends the data.

Description The SyncE behaves the same as SDH on the networking application.

The clock transmission is also based on the physical link. The SyncE requires all nodes on the clock transmission path to support the SyncE technology.

Page 16: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Synchronous Ethernet The ZXCTN PTN devices compose the SyncE network, supporting the

SyncE interace to achieve the Ethernet synchronization at the physical layer. The typical application is shown in the figure below:

In the SyncE environment, the clock signal of the devices, such as GPS, and BITS, passes the SyncE interface to achieve the clock synchronization for the ZXCTN PTN devices of the entire network. The ZXCTN device connected with BTS and NodeB, transmits the extracted clock signal to BTS or NodeB through the SyncE interface, and finally achieves Ethernet clock synchronization over the entire network.

Ethernet ring

TS information

Page 17: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

SyncEthernet Technology Ethernet SSM Frame Format

a frame ESMC (Ethernet Synchronization Messaging Channel) that transmits the clock synchronization quality grade is defined in the SyncE.

Octet number Size Field

1-6 6 Octets Destination Address =01-80-C2-00-00-02 (hex)

7-12 6 Octets Source Address

13-14 2 Octets Slow Protocol Ethertype = 88-09 (hex)

15 1 Octets Slow Protocol Subtype =0A (hex)

16-18 3 Octets ITU-OUI = 00-19-A7 (hex)

19-20 2 Octets ITU Subtype

21 4 bits Version

1 bit Event flag

3 bits Reserved

22-24 3 Octets Reserved

25-1532 36-1490 Octets Data and Padding (See point J)

Last4 4 Octets FCS

Page 18: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

SyncEthernet Technology

Ethernet SSM Frame Format The QL TLV frame where the SSM information is placed, resides in the information payload starting from No.25 in the ESMC frame.

8 bits %Type: 0x01

16 bits %Length: 0x04

%4 bits %0 (unused)

%4 bits %SSM code

Page 19: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Contents

Introduction to Synchronization Principle How to Achieve Synchronization

Technology SyncEthernet Technology TOP technology IEEE1588V2 ( PTP )

ZXCTN Series Device Synchronization Function

Synchronization Configuration Instance

Page 20: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

TOP technology TOP (Timing Over Packet) is a FS technology, namely, bearing the

cock frequency in a specific TOP packet, and separating it from the packet when necessary, thus to achieve the transparent transmission of the clock frequency on PSN. It is only necessary to configure TOP Server and TOP Client nodes to support TOP packets which are forwarded like other service packets when passing the middle nodes. We refer to the device that translates clock frequency to packets as TOP Server, and the device that translates packets to clock frequency as TOP Client.

TOP has two work modes: Differential Mode and Self-Adaptive Mode. The differential mode is applied when the network where TOP Server and TOP Client reside is synchronized or the node contains the shared clock, however the client's service clock should be transmitted transparently. The self-adaptive mode is applied in synchronization procedure of the service clock from TOP Server to TOP Client when the network where TOP Server and TOP Client reside, is asynchronized.

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TOP Technology - Differential Mode

The differential mode is a typical mode specified in G.8261. The devices on both ends: TOP Server and TOP Client, share the FS clock. The PSN network that the TOP packet penetrates can both synchronized and asynchronized. At the TOP Server end, the difference: f, between the service clock frequencyand the common clock △frequency is coded and borne in the TOP packet. At the TOP Client end, this common clock is used to restore the service clock at the remote end (receiving end) of the packet network.Because both TOP Server and TOP Client have a standard clock, as long as the frequency difference can be delivered to the Client end in a certain time, the service clock can be restored. The clock frequency is hardly affected by the delay jitter of the PSN network.

Sync Cl ock

Servi ceCl ock

f TOP报文

Sync Cl ock

fTOP报文 Servi ceCl ock

PSN

TOP Server TOP Cl i ent

Page 22: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

TOP Technology - Adaptive Mode

The adaptive mode is applied when the NE device clocks where TOP Server and TOP Client reside respectively are not in synchronous relation, so the clock frequency cannot be restored through the differential mode.

Likewise, the problem of restoring the adaptive clock frequency is to find the PSN delay jitter variation rule between the two non-synchronization network (TOP Server and TOP Client), and remove it in order to synchronize the clock frequency.

Page 23: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Contents

Introduction to Synchronization Principle How to Achieve Synchronization

Technology SyncEthernet Technology TOP technology IEEE1588V2( PTP)

ZXCTN Series Device Synchronization Function

Synchronization Configuration Instance

Page 24: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

IEEE1588V2 ( PTP ) Overview

IEEE 1588V2 is a precision time synchronization protocol, called PTP for short. It is active/standby synchronization system. Its core thought is to adopt the active/standby clock mode to code the time information, and use the network symmetry and delay measurement technology to achieve the active/standby synchronization.

Page 25: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

IEEE1588V2 ( PTP ) Work Procedure

During the system synchronization, the master clock periodically releases the PTP and the time stamp; and the slave clock port receives the time stamp sent from the master clock port. According to this time, the system calculates the time delay of the master and slave lines and the master/slave time difference, and uses this time difference to regulate the local time, keeping the consistent frequency and phase of the master/slave device time.

The IEEE 1588 protocol supports the following work modes:

Ordinary Clock: Only one port supports the 1588 protocol. Border Clock: Multiple ports support the 1588 protocol. Transparent Clock: The 1588 protocol does not run on the node,

but the time stamp needs to be modified. When the time packet is forwarded, the time when the local node processes this packet should be filled in the modification position.

Management node: The NM interface function is added on the basis of the above-mentioned mode.

Page 26: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

IEEE1588V2 ( PTP ) Introduction to work mode

The IEEE 1588 divides the clock inside the network into two types: Ordinary Clock (OC) and Border Clock (BC). BC usually resides on the network (switch and router) whichis not stable.

In terms of the communciation relation, the clock can be divided into master clock and slave clock. Theoretically, all clocks can act as the master clock and the slave clock. In the system, the optimal clock is the highest-level clock with the best stablity, precision and assurance.

According to the clock precision, class and the traceability of the UTC on each node, the master clock inside each subnet shall be automatically selected by the Best Master Clock (BMC).

In a system with only one subnet, the master clock is the Global Master Clock (GMC). Each system has only one GMC and each subnet has only one master clock. The slave clock is kept synchronized with the master clock.

Page 27: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

IEEE1588V2 ( PTP ) 1588 Clock Networking Diagram

link

Master/slave clock

Border clock

Slave clock

Clock stream

Page 28: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

IEEE1588V2 ( PTP ) Transmission Process of the IEEE 1588 Clock

Master clock

Slave clock

1588 transparent transmission and border clock

Page 29: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

IEEE1588V2 ( PTP ) Transmission Process Details

The key point of IEEE 1588 lies in the delay measurement. To measure the network transmission delay, IEEE1588 defines a

delay request information packet, Delay Request Packet (Delay_Req.).

The slave clock sends a Delay Request at T3 after receiving the time information sent by the master clock. The master makes a time-stamp showing the accurate receiving time T4, on the Delay Request Packet Delay Response packet after receiving the Delay Request, and sends it to other slave clocks. Therefore, the slave clocks can accurately compute the delay in the network.

For the detailed procedure, refer to the next page.

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IEEE1588V2 ( PTP ) Delay measurement in 1588

mode: Because:

T2 - T1 = Delay + Offset T4 - T3 = Delay - Offset we can obtain: Delay= [ T2 - T1 + T4 -

T3 ] /2 Offset= [ T2 - T1 - T4 +

T3 ] /2 According to Offset and Delay, The time information can be

modified on the node. thus, to achieve the time

synchronization between the master and slave nodes.

Page 31: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Comparison of Three Technologies

Technology Advantages Disadvantages Preferential Applicataion Site

SyncEthernet Technology

Each to achieve; Less impact by the PSN network damage; Clock synchronization quality close to SDH; Similar structure to SDH; Mature technology

SyncE requires each node on the network to support SyncE to achieve the clock synchronization in the entire network; Number of PHY supporting clock extraction is limited.

PSN network frequency synchronization

TOP technology

Able to perform cross-network transparent clock transmission; Not require all nodes on the network to support the TOP packet processing; Flexible application

Easy to be affected by PSN network; no standards so that each manufacturer cannot interconnect with one another

PSN cross-network synchronization and transparent transmission of PSN service clock

IEEE1588 V2 technology

Able to recover the time to achieve time synchronization With standards easy for interconnection

Hardly affected by PSN network; Each node on the network required to support 1588 processing

Used in PSN time synchronization

Page 32: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Contents

Introduction to Synchronization Principle How to Achieve Synchronization ZXCTN Series Device Synchronization

Function ZXCTN 6000 Series Devices ZXCTN 9000 Series Devices

Synchronization Configuration Instance

Page 33: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 6000 Synchronization Function

Overview As a packet transmission device with the network-

class clock synchronization, the ZXCTN6000 system is capable of selecting the synchronization clock source as the system clock through multiple ways to achieve the PTN network clock synchronization.

Page 34: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 6000 Synchronization Function System clock function

Providing BITS external clock input, output interface: Provides the external clock output interface (2.048 Mbit/s or 2.048 MHz) and clock input interface (2.048 Mbit/s or 2.048 MHz ) used to extract the clock and clock synchronization status information.

Supporting the GPS (Global Positioning System) interface function: Provides 1 PPS (Pulse Per Second) + ToD signal. The device provides the GPS input or output. It also supports the GPS clock recovery and 1PPS lock phase loop.

Supporting 1588 frequency recovery Supporting SyncE interface and the SyncE clock source setting Supporting extracting the clock signal from the E1 interface and providing the

clock signal compliant with the ITU-T G.813 standards Supporting the transparent transmission of customer clock on the circuit

emulation E1 interface Supporting transmitting the SSM information, achieving the whole network clock

synchronization according to the SSM information, supporting automatically selecting high-priority clock, and preventing timing looping.

Supporting the work modes, such as the hyper snap mode, tracing mode, hold-on mode, and the free running mode

Supporting monitoring and reporting the clock alarms on the system and cards

Page 35: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 6000 Synchronization Function

Time Protection Function Adopts the basic SSM protocol and the extended SSM

protocol to achieve the auto protection of the clock link and ensure the clock's reliable transmission.

Selects an algorithm to compute the best clock information synchronization path and prevent the clock looping.

Provides protection switchover function for the clock information according to the clock path algorithm, when the network fault occurs.

Provides the functions of synchronization locking , suspension and free oscillation for the clock information.

Page 36: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 6000 Synchronization Function Time Transmission Function

The time SyncE constituted by ZXCTN 6000 has the following time transmission functions:

Supporting PTP function on the Ethernet port and the SDH port The port supports one-step PTP protocol and the two-step PTP

protocol. Supporting processing the link delay measurement protocol Supporting setting the clock node type which includes: Ordinary

Clock, Border Clock, E2E Transparent Clock, and Ordinary Clock + E2E Transparent Clock

Supporting setting the PTP port mode According to the NM setting, the device supports enabling or

disabling the 1588 protocol time synchronization function on each Ethernet port.

The system supports the Manual Mode, SSM Protocol Mode, or BMC Protocol Mode to determine the ports where the TS function is enabled to work in three work modes: on the Master Port, on the Slave Port, or Passive.

Supporting TS management function: TS Configuration, Querying, and Alarm Performance Monitoring

Page 37: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 6000 Synchronization Function

Time Protection Function Adopts the basic SSM protocol and the extended SSM

protocol to achieve the auto protection of the clock link and ensure the clock's reliable transmission.

Selects an algorithm to compute the best clock information synchronization path.

Supports the TS protection switchover function. Provides protection switchover function for the clock information according to the clock path algorithm, when the network fault occurs.

Supports delay compensation: Each time port of the device supports setting the time delay compensation.

Page 38: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Contents

Introduction to Synchronization Principle How to Achieve Synchronization ZXCTN Series Device Synchronization

Function ZXCTN 6000 Series Devices ZXCTN 9000 Series Devices

Synchronization Configuration Instance

Page 39: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 9000 Synchronization Function

Overview As a packet transmission device with the network-

class clock synchronization, the ZXCTN9000 system is capable of selecting the synchronization clock source as the system clock through multiple ways to achieve the PTN network clock synchronization.

Page 40: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 9000 Synchronization Function

System clock function Supporting SyncE interface and the SyncE clock source setting Supporting extracting clock from the channelized STM-1/STM-

4/STM-16/STM-64 interfaces Supporting extracting clock from the ATM STM-1 interface Supporting the SSM information transmission The clock unit achieves the whole network clock synchronization

according to the SSM information, supporting automatically selecting high-priority clock, and preventing timing looping.

Supporting the work modes, such as the hyper snap mode, tracing mode, hold-on mode, and the free running mode

Supporting monitoring and reporting the clock alarms on the system and cards

Page 41: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 9000 Synchronization Function

Time Protection Function ZXCTN 9000 adopts the basic SSM protocol and the

extended SSM protocol to achieve the auto protection of the clock link and ensure the clock's reliable transmission.

Selects an algorithm to compute the best clock information synchronization path and prevent the clock looping.

Provides protection switchover function for the clock information according to the clock path algorithm, when the network fault occurs.

Provides the functions of synchronization locking , suspension and free oscillation for the clock information.

Page 42: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 9000 Synchronization Function Time Transmission Function

The time SyncE constituted by ZXCTN 9000 has the following time transmission functions:

Supporting PTP function on the Ethernet port and the SDH port The port supports one-step PTP protocol and the two-step PTP

protocol. Supporting processing the link delay measurement protocol Supporting setting the clock node type which includes: Ordinary

Clock, Border Clock, E2E Transparent Clock, and Ordinary Clock + E2E Transparent Clock

Supporting setting the PTP port mode According to the NM setting, the device supports enabling or

disabling the 1588 protocol time synchronization function on each Ethernet port.

The system supports the Manual Mode, SSM Protocol Mode, or BMC Protocol Mode to determine the ports where the TS function is enabled to work in three work modes: on the Master Port, on the Slave Port, or Passive.

Supporting TS management function: TS Configuration, Querying, and Alarm Performance Monitoring

Page 43: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

ZXCTN 9000 Synchronization Function

Time Protection Function Adopts the basic SSM protocol and the extended SSM

protocol to achieve the auto protection of the clock link and ensure the clock's reliable transmission.

Selects an algorithm to compute the best clock information synchronization path.

Supports the TS protection switchover function. Provides protection switchover function for the clock information according to the clock path algorithm, when the network fault occurs.

Supports the delay compensation function. Each time port of the device supports setting the time delay compensation.

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Contents

Introduction to Synchronization Principle How to Achieve Synchronization ZXCTN Series Device Synchronization Function Synchronization Configuration Instance

Configuring Clock Source SSM Mode Configuration External Clock Export 1588 Time Node Configuration 1588 Time Port Configuration GPS Parameter Configuration E1 Port Clock

Page 45: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Clock and 1588 Functional NM Configuration Instances Configuring Clock Source

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Clock and 1588 Functional NM Configuration Instances

SSM Mode Configuration

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Clock and 1588 Functional NM Configuration Instances

External Clock Export

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Clock and 1588 Functional NM Configuration Instances

Configuring 1588 Time Node

Page 49: PTN Synchronization Subject V1.0. Contents Introduction to Synchronization Principle Basic Concepts of Synchronization Difference between Time Synchronization

Clock and 1588 Functional NM Configuration Instances

Configuring 1588 Time Port

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Clock and 1588 Functional NM Configuration Instances

Configuring GPS Parameter

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Clock and 1588 Functional NM Configuration Instances

Configuring E1 Port Clock

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Problems and Discussions

What is the difference between 2Mbit/s (2.048Mbit/s) and 2MHz? 2Mbit/s: digital signal, square wave 2MHz: analog signal, sine wave

What do the system clocks 2.048, 19.44M, 25M, and 125M work as? 2.048M: used by the 2M external clock (supporting

2Mbits/s instead of 2MHz) 19.44M: Used by TDM E1 and IMA E1 25M: Used for 8 FE interfaces of the master board

and 8 FE interfaces of two FE subcards 125M: Used for 2 GE interfaces on the master board

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