Xiaguang PTN network IEEE1588 synchronization engineering test process

1 Introduction

At present, with the development of PTN network construction, IEEE1588 time synchronization technology is about to be widely used. There are no clear specifications for the test items, test steps, and troubleshooting processes of the engineering installation of the PTN synchronization system network. As a result, the current PTN synchronization engineering maintenance test is in a situation where each is doing its own thing. There is no relatively standardized and unified standard, which has a certain impact on the construction progress of the PTN network.

According to the PTN synchronous engineering maintenance test solution of XG7010, combined with the actual situation and work flow of engineering maintenance, we have summarized the PTN synchronous engineering maintenance test process and given the content that needs to be tested in each step, providing a set of effective methods for the standardization of PTN synchronous engineering and maintenance for reference by mobile operators, PTN manufacturers and engineering maintenance companies.

2. PTN synchronization engineering maintenance test steps of XG7010

In actual projects, we recommend that when conducting synchronization tests, the principle of testing the clock first and then the time should be adopted for engineering maintenance testing. First, the clock frequency should be unified to ensure the normal transmission of the business, and then the time test, optical path asymmetry compensation and other aspects should be carried out.

2.1 Overall Process

When performing work such as PTN network equipment installation, service debugging, project acceptance, service cutover, maintenance and troubleshooting, you must first have an overall understanding of the test items and test processes for synchronization testing in the entire PTN network system, so that you can effectively integrate these processes into the entire PTN network engineering maintenance test, establish standards and specifications, and improve work efficiency.

Below we give the overall process of IEEE1588 synchronous engineering maintenance test of PTN network for reference only, as shown in Figure 1.

Figure 1 Overall process of PTN synchronous engineering maintenance test

2.2 Summary of test contents

1) PTP synchronization time server test

It is necessary to use instruments to test the time output by the PTP time synchronization server, the deviation of the clock signal, and whether the PTP protocol data transmission is normal. In addition, the drift characteristics (MTIE and TDEV) of the time and clock signal of the PTP time synchronization server can be evaluated.

Change the GPS timing mode to the Beidou timing mode, observe the changes in the time output during the switching process and conduct long-term stability tests after the switching.

2) Test and evaluation of optical path asymmetry compensation

Compensation is performed in a segmented manner, relying on professional instruments to accurately measure the delay caused by path asymmetry, formulating compensation strategies in advance, and conducting point-by-point testing and evaluation. This link is very important during construction and acceptance, and can effectively ensure the correctness of IEEE1588 time synchronization information and ensure the time uniformity of the entire network.

3) Test and evaluation of protection path asymmetry compensation

Protection switching can be performed point by point to evaluate the asymmetric compensation value of the protection path.

4) Testing of PTN equipment synchronization performance

The instrument is required to test the time deviation and clock accuracy of the time synchronization interface of the PTN equipment, receive IEEE1588 protocol data from the Ethernet optical interface and electrical interface of the PTN equipment, and parse out the relevant time information for verification. If necessary, the drift characteristics of the clock signal of the PTN equipment can be tested.

Business stress testing to detect the impact of business changes on the synchronization system.

The impact of automatic protection switching of PTN equipment on network synchronization performance.

The network management system and the instrument can also be used to complete the synchronization reference source setting test, mainly to check whether the synchronization reference source setting is correct; the synchronization source switching test, mainly to observe the impact on the service during switching; the clock retention feature, to test the frequency accuracy and stability of the device's clock when it is working in the retention state, and its impact on the service.

5) Base station synchronization test

When testing the base station synchronization system, the main measurements are time deviation and clock signal, and the clock drift index can be tested to evaluate the long-term stability of time and clock synchronization.

3. Summary

Above, we have briefly explained the steps and processes of IEEE1588 synchronous engineering maintenance testing for PTN networks. We hope to provide some suggestions and references for the standardized operation of PTN synchronous engineering maintenance testing, and continuously improve it in practice.