1.1.1 Configuring Delay Compensation for the Source Node
The source OTN node is generally connected to the BITS device. They can be interconnected in either of the following modes (for details, see section 2.1.4 ):
l Connected through a 2M clock port and a 1PPS+TOD port on a clock interface board
l Connected through a GE port on the TN52STG board
Delay compensation is configured in a similar way in both modes. The detailed procedure is as follows:
1. Determine clock synchronization status of the source node.
In either interconnection mode, check clock synchronization status using the following method:
l Check physical clock synchronization status.
− Select the NE in NE Explorer and choose Configuration > Clock > Physical Clock > Clock Synchronization Status from the Function Tree.
− Click Query. Check the query result to see whether the NE is tracing the clock provided by the BITS device.
l Check PTP clock synchronization status.
− Select the NE in NE Explorer and choose Configuration > Clock > PTP Clock > Clock Synchronization Attribute from the Function Tree.
− Click Query. Check the query result to see whether the NE is tracing the clock provided by the BITS device.
2. Measure delay.
After ensuring that the source node is tracing the clock provided by the BITS device, verify time precision of the source node.
Set the port to be tested to a 1PPS+TOD output port. For details on how to use the test instrument, see chapter 5.
When the test instrument is stably tracing the GPS, connect the test cable to the TOD port on the OTN equipment. Considering the delay caused by the antenna feeder and test cable, check the time displayed on the test instrument 10 minutes later. When the maximum time difference does not exceed 50 ns, record the time offset of the OTN equipment. Then, configure asymmetry delay compensation using the U2000 or Navigator.
3. Compensate for delay.
On the OTN equipment, delay may be caused by a cable or service board. You can configure delay compensation using the U2000 or Navigator.
Record delay compensation-related parameters in Port Compensation (column V) in the PTP Clock Configuration sheet of the Configuration List for future maintenance.
l Compensate for delay caused by a cable connecting the BITS device's 1PPS+TOD port to the OTN equipment.
− Configure delay compensation using the U2000.
For details on how to configure delay compensation using the U2000, see step 14 in section 3.4.1 .
− Configure delay compensation using the Navigator (connect network cables on site).
Run the following command to compensate for delay.
:cfg-set-ptpcablelength:15,0,ptp1,receive,time,100;
This command configures delay compensation only for the receive direction of 1PPS+Time.
In the preceding command, "15" indicates the slot ID (in master/slave subrack mode, a number can be added in front of a slot ID to indicate the subrack ID, for example, 1–15 or 2–15); "ptp1" indicates the port; "100" indicates the measured value applied.
l Compensate for delay caused by a service board.
− Configure delay compensation using the U2000.
For details on how to configure delay compensation using the U2000, see step 11 in section 3.4.1 .
− Configure delay compensation using the Navigator (connect network cables on site).
Run the following command to compensate for delay.
:cfg-set-ptplinewarp:4,0,1,time,positive,100;
If a slave port is compensated for positive xxx ns, the corresponding master port must be compensated for negative xxx ns.
In the preceding command, "4" indicates the slot ID (in master/slave subrack mode, a number can be added in front of a slot ID to indicate the subrack ID, for example, 1-4 or 2-4); "1" indicates the port; "positive" indicates the positive direction; "100" indicates the measured value applied. To associate parameters, run the :cfg-set-ptplinewarp command.
4. Calibrate delay.
After delay compensation is completed, check the time difference on the OTN equipment after 10 minutes. If the maximum time difference does not exceed 50 ns, the delay compensation satisfies requirements. Otherwise, configure delay compensation again.
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1.1.2 Configuring Delay Compensation for the Intermediate Nodes
For details on how to measure asymmetry delay at an intermediate node and how to compensate for the delay, see section 3.5.4 .
The method of measuring asymmetry delay at an intermediate node varies according to the configuration.
1. TN11ST2+SFIU boards
This configuration simplifies asymmetry delay compensation (no site-by-site compensation) during deployment. That is, you only need to select sites for delay compensation and the maintenance engineers will configure delay compensation at the selected sites.
Adhere to the following principles when configuring delay compensation during deployment:
l Time will be transmitted to the downstream nodes and time must be received over two or more paths.
l Delay compensation must be configured for OTN equipment connected to PTN equipment and the OTN equipment must satisfy time precision requirements.
l At a node, compensating for a time offset caused by path switching must be completed. This ensures that the time reaching downstream nodes satisfies requirements after time source switching.
Example:
As shown in Figure 2-2, each of sites A, B, and C provides one port for transferring time sources to the downstream nodes and two or more ports for receiving time sources. At these sites, delay compensation is required for path switching. After the delay compensation, no more delay compensation is required during maintenance.
2. OTU service boards or TN11ST2+FIU boards
This configuration requires site-by-site asymmetry delay compensation and the compensation must cover all paths at a site.
For example, site C in Figure 2-2 has two time tracing paths: B-C and D-C. Compensate for delay on path B-C (for details, see section 3.5.4 ), switch the time source (by disabling a port on path B-C), and then compensate for delay on path D-C. Finally, enable the port on path B-C.
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1.1.3 Configuring Delay Compensation for the Sink Node and PTN Equipment
OTN equipment may be connected to PTN equipment in either of the following modes:
l Connected through a 2M clock port and a 1PPS+TOD port on a clock interface board used with the TN52STG board
l Connected through a GE port on the TN52STG board
The commissioning procedure is the same regardless of the interconnection mode.
1. Measure time precision of the OTN equipment.
Measure delay for the OTN equipment to be connected to PTN equipment. For details on how to configure delay compensation, see section 3.5.4 .
2. Measure time precision of the PTN equipment.
Work with PTN maintenance personnel and compensate for delay on PTN equipment. For details, see section 3.5.4 . The GUIs or commands for configuring delay compensation may be different from those provided in this document.
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1.2 Verifying IEEE 1588v2
Verify all the IEEE 1588v2-related test cases according to the IEEE 1588v2 Verification Schemes for xxx FOA Site and site plans. Ensure that IEEE 1588v2 complies with the essential specifications.
l Formulate an acceptance plan including items and sites for acceptance.
l Modify configurations on the U2000, if required. For details, see section 3.4 .
l Calibrate test instruments. For details on how to calibrate test instruments and how to use test instruments, see section 3.5.2 and chapter 5 respectively.
l Do not modify configurations during the acceptance test. If configurations have to be modified, record the modifications and restore the original configurations after the acceptance test is completed.
l Take essential precautions during the acceptance test. For details, see section 3.7.2 .
l Record the test result in detail for each test case.
l Generate an acceptance report and summarize the deployment acceptance activities.
