Testing Synchronous Ethernet Wander with the Ixia · PDF file1 26601 Agoura Road Calabasas, CA 91302 Tel + 1-818-871-1800 Fax + 1-818-871-1805 P/N: 915 -6556 01 Rev. C May 2013

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26601 Agoura Road Calabasas, CA 91302 Tel + 1-818-871-1800 Fax + 1-818-871-1805 www.ixiacom.com P/N: 915-6556-01 Rev. C May 2013

Testing Synchronous Ethernet Wander with the Ixia Anue 3500

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Overview

As the demand for advanced mobile broadband services continues to increase, many network providers and carriers are migrating their mobile backhaul networks from legacy synchronous transports such as SONET/SDH and T1/E1 to Carrier Ethernet. To deliver synchronization services, Synchronous Ethernet (“SyncE”) is increasingly being used, alone or in conjunction with IEEE 1588 (precision time protocol, PTP). The need to test the providers’ services and equipment on their new SyncE networks has emerged, and the ITU-T G.8262 standard provides applicable tests to verify that SyncE equipment and applications will function correctly under a range of timing impairment conditions known collectively as “wander”.

The Ixia Anue 3500 allows for the comprehensive testing of Synchronous Ethernet (SyncE) as specified in ITU-T G.8262:

TEST REQUIREMENT

Wander Generation ITU-T G.8262 Section 8 “Noise Generation”

Wander Tolerance ITU-T G.8262 Section 9 “Noise Tolerance”

Wander Transfer ITU-T G.8262 Section 10 “Noise Transfer”

Wander Generation refers to the phase noise that is introduced by the DUT alone, i.e. the difference in phase between the input reference clock on the DUT and the SyncE recovered clock on the DUT’s Ethernet output.

Wander Tolerance refers to the ability of the DUT to tolerate phase noise that is introduced by the physical network present between two SyncE devices.

Wander Transfer refers to the phase noise present on the DUT’s input that is transmitted to the SyncE Ethernet output or slave clock.

Details of these requirements are available in Recommendation ITU-T G.8262 – Timing characteristics of a synchronous Ethernet equipment slave clock.

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Acronyms and Definitions

EEC Synchronous Ethernet Equipment Clock

TIE Time Interval Error

MTIE Maximum Time Interval Error

Phase noise See Wander

PRC Primary Reference Clock

SyncE Synchronous Ethernet

TDEV Time Deviation

Wander Phase variation of the clock signal with respect to an ideal reference clock

Test Bed Topology

SyncE Wander testing is accomplished primarily by measuring and/or inserting wander (phase noise) into the timing signal carried over SyncE. The Ixia Anue 3500 provides the capability to emulate the network timing characteristics by inserting wander, and also measures wander generated or transferred by the DUT. The reference clock is also supplied to the DUT EEC (acting as Master) by the Ixia Anue 3500 over 2.048 MHz BNC, 10 MHz BNC, T1 BITS RJ48C, or E1 MTS RJ48C.

Required Equipment and Software

Ixia Anue 3500

Host PC

DUT – System or application to be tested

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Test System Diagram

Figure 1: Test Topology Diagram

Test System Setup

1. Connect an external reference clock to the Ixia Anue 3500. The Ixia Anue 3500 supports external reference clocks from the following sources:

CLOCK SOURCE INTERFACE

2.048 MHz BNC

10 MHz BNC

T1BITS RJ48C

E1 BITS RJ48C

Connect the appropriate cable (BNC or RJ48C) to the clock input interface at the left of the Ixia Anue 3500 front panel:

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Figure 2: Connecting Clock Input Interface to the Ixia Anue 3500

Note: The Ixia Anue 3500 is also equipped with an internal OCXO Stratum-3 oscillator, which can be used as a system clock reference in the absence of a quality lab reference clock. For best results, a high-quality external reference clock should be used.

2. Configure the 3500’s reference clock input for the appropriate port.

Figure 3: Configure the System Clock

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Figure 4: Selecting the System Clock Reference

Test Cases

The following test cases are derived from ITU-T G.8262, sections as described.

Wander Generation

Wander Tolerance

Wander Transfer

All test cases use the test bed topology described above, or a variant of the described test topology.

Wander Generation

This test measures the wander (phase noise) present on the DUT’s output when an ideal input reference signal is supplied by the Ixia Anue 3500. The difference in wander present on the DUT’s output compared to the ideal input reference clock is the wander that is generated by the DUT. The wander generated by the DUT is measured in terms of Maximum Time Interval Error (MTIE) and Time Deviation (TDEV).

The measurement of generated wander MTIE and TDEV is performed by the Ixia Anue 3500, and evaluation against the limits specified in ITU-T G.8262 is automatically performed and pass/fail indication is provided by the Ixia Anue 3500 GUI.

For additional details see ITU-T G.8262, section 8 Noise generation.

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Test Setup

Figure 5: Wander Generation Test Setup

1. Connect and configure the Reference Clock Source according to Appendix B, Configuring Outbound Reference Clocks, located at the end of this document.

2. Connect the DUT system Ethernet output to the Ixia Anue 3500 Ethernet port 1 (eth1) and configure using the Ixia Anue 3500 Control Panel Ports tab. Double-click the port that will be connected to the DUT EEC Master’s Ethernet port. The Ethernet Port Property dialog will display.

Figure 6: Selecting the Ethernet Port Connected to the DUT

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Figure 7: Configuring the Ethernet Port for Measuring Wander

3. From the Ixia Anue 3500 Control Panel Wander tab, configure the Ixia Anue 3500 for wander measurement by double-clicking a Wander Measurer. The Edit Wander Measurer dialog will display.

Figure 8: Selecting a Wander Measurer from the Wander Tab

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Figure 9: Editing the Wander Measurer

Test Steps

1. The test begins when the configuration is complete.

Results

1. From the Ixia Anue 3500 Control Panel Wander tab, open the TIE graph and MTIE/TDEV results graphs.

Figure 10: Wander Measurer Context Menu

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Figure 11: Viewing Results in the MTIE/TDEV Result Graphs Window

2. Evaluate G.8262 Option 1 by configuring the masks in the MTIE/TDEV Results Graph.

Figure 12: Selecting the MTIE/TDEV Result Masks

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Figure 13: G.8262 Option Results

3. According to G.8262 Section 8, the measurement interval for TDEV measurement is 12 times tau, with a maximum tau of 1,000 seconds. Allow results to accumulate for 3h20m (12,000 seconds) for a G.8262 compliant TDEV test result.

4. For MTIE results, the test should be conducted until the maximum tau value present in the selected mask has a measurement value.

5. Evaluate G.8262 Option 2 by selecting the Option 2 masks as in Step 2-3. The Option 1 and Option 2 results can be collected at the same time and displayed on the same graph. Pass/fail evaluation for both masks is displayed in real time.

6. The Ixia Anue 3500 provides automatic and real-time pass/fail results in the MTIE/TDEV graph window, both in graphical MTIE & TDEV format as well as simple pass and fail indication. Results are displayed for up to three MTIE masks and three TDEV masks at the same time.

7. When you close the TIE window, you are prompted to save the TIE data to a file. You can save the data for later analysis.

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Wander Tolerance

This test measures the DUT’s ability to tolerate the maximum level of wander (phase noise) that may be present in the network without causing failure of the synchronization system.

The wander introduced to the DUT (input wander) must not cause any of the following:

Alarms

The clock to switch reference

The clock to go into holdover

Input wander is specified in terms of Maximum Time Interval Error (MTIE) and Time Deviation (TDEV).

For the wander tolerance test, wander is generated by the Ixia Anue 3500. Evaluation of passing and failing is accomplished by observing the DUT alarms and clock status.

For additional details see ITU-T G.8262, section 9 Noise tolerance.

Test Setup

Figure 14: Wander Tolerance Test Setup

1. Connect the DUT EEC Slave’s Ethernet input (100M/1G/10G) to an Ixia Anue 3500 Ethernet port (Optical or Copper as needed), and configure by double-clicking the selected port in the Ixia Anue 3500 Control Panel Ports tab.

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Figure 15: Selecting the Ethernet Port from the Ports View

Figure 16: Configuring Ethernet Port for Wander Insertion

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2. Configure a wander generator to add the specified wander with the Ixia Anue 3500 Control Panel Wander tab.

Figure 17: Selecting a Wander Generator from the Wander Tab

Figure 18: Editing the Wander Generator

3. To make the 3500 emulate the EEC Master, set up ESMC Generation on the Ethernet port with the Ixia Anue 3500 Control Panel Ports tab.

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Figure 19: Selecting the ESMC Properties

Figure 20: Configuring ESMC Properties

4. Attach the Host PC to the DUT in order to monitor clock status and alarms (see DUT documentation) for the duration of the test.

Test Steps

1. Start the test starting the WG01 Wander Generator in the Wander tab of the Ixia Anue 3500 GUI.

Figure 21: Starting the Wander Generator from the Wander Tab

2. For EEC-Option 1, monitor the DUT, noting any occurrence of the following:

Alarms

Clock switch reference

Clock going into holdover

Results

1. The test fails if there is any occurrence of the following while monitoring the DUT:v

Alarms

Clock switch reference

Clock going into holdover

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Wander Transfer

This test measures the amount of SyncE wander introduced to the DUT (input wander) that is transferred to the output of the DUT, in terms of gain.

For the wander transfer test, input wander is generated on one port of the Ixia Anue 3500. The output wander from the DUT is measured on another port of the Ixia Anue 3500.

For additional details see ITU-T G.8262, section 10 Noise transfer.

Test Setup

Figure 22: Wander Transfer Test Setup

1. From the Ixia Anue 3500 Control Panel, select Wander Transfer from the File menu to enter Wander Transfer mode.

2. First, calibrate the Ixia Anue 3500 for wander transfer by connecting an Ethernet cable between the two Ethernet test ports (eth1 and eth2), and perform the calibration procedure in steps 3-4 below.

Note: The calibration steps must only be completed one time, and they are optional. To begin testing without calibrating, skip to step 5.

3. Load the Wander Transfer table and complete the Self-Cal.

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Figure 23: Performing Self-Cal for Wander Transfer

Figure 24: Configuring the Wander Transfer Test

4. Confirm when prompted and the self-calibration will begin. Wait for the Self-Cal to complete, and then continue to Wander Transfer testing. It is recommended to save the test file after the calibration completes.

Note: For the most accurate measurements, Self-Cal should be completed for each system for all frequencies being measured and for each interface type (Copper or Optical) at least one time for a given test. Subsequent runs of the same test can be done with the same calibration data set. Self-Cal can take several hours to run.

5. Connect each of the 3500’s Ethernet ports to the DUT Ethernet ports (100M/1G/10G) as shown in the Test Setup diagram in Section 5.3.1

6. To make the 3500 emulate the EEC Master, set up ESMC Generation on the Ethernet port with the Ixia Anue 3500 Control Panel Ports tab.

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Figure 25: Selecting ESMC Properties

Figure 26: Configuring ESMC Properties

Test Steps

1. Start the Wander Transfer test.

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Figure 27: Starting the Wander Transfer Test

Results

1. As soon as the first step in the Wander Generator table has completed, the Wander Transfer graph will be displayed, showing the results in real time as each step is completed. You can also open the Wander Transfer graph at any time during the test by pressing the “Transfer Graph” button.

2. When the Wander Transfer graph is opened, select the mask “G.8262 EEC-Option 1” in order to have the results automatically evaluated based on the mask.

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Figure 28: Selecting the Mask for Wander Transfer

3. The results are displayed in the Transfer Graph.

Figure 29: Viewing Results for Wander Transfer

4. The Ixia Anue 3500 calculates pass/fail results in real time for the duration of the test, while graphically plotting the data points.

5. After the test completes, you may save the results using the save option in the Wander Transfer dialog. Multiple tests can be run and saved to the same file. These multiple data sets can be reviewed concurrently on the same graph.

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Appendix A

This section identifies SyncE test applications that are not derived from the G.8262 standard, but may be useful in a real-world test environment for development or troubleshooting of SyncE equipment.

Microwave Backhaul Configuration

Synchronous Ethernet is frequently used with microwave Ethernet backhaul equipment, where the microwave antennas and transceivers are deployed in place of physical copper or fiber that would be present in a traditional Ethernet deployment. The Ixia Anue 3500 fully supports testing of Synchronous Ethernet over Microwave. The following is an example topology for testing.

Figure 30: Sync Over Microwave Test Setup

Testing 10GE and 1GE Simultaneously

The Ixia Anue 3500 can be used to test 100MB/1GE and 10GE simultaneously, such as in two separate test beds. The 1GE and 10GE interfaces are on separate data paths. The interfaces operate independently, and with multiple wander generators and multiple wander measurers, as well as Network Profiles for each port, completely independent testing is fully supported.

While multiple tests can be run simultaneously, the Ixia Anue 3500 does not support multiple user logins.

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Figure 31: 1GE and 10GE Simultaneous Test Setup

Appendix B – Configuring Outbound Reference Clocks

The Ixia Anue 3500 can provide a reference clock source via 2.048 MHz BNC, 10 MHz BNC, T1 BITS RJ48C or E1 MTS RJ48C. This facilitates connection to a variety of DUT EEC systems. This reference clock source can be used to synchronize the DUT with the 3500 for testing, as well as to add wander to the DUT’s reference clock input

1. Connect the appropriate Reference Clock Source from the Ixia Anue 3500 REF / 1PPS / GPIO or DS1 / E1 port to the Reference Clock Input on the DUT System

2. For BNC ports running 10 MHz, use a Wander Generator to create a wander-free clock source, and then set the output port’s clock source to this Wander Generator

a. Identify a Wander Generator that is not going to be used for testing (e.g. WG02). Configure this Wander Generator by double-clicking it from the Wander tab of the Ixia Anue 3500 Control Panel.

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Figure 32: Configuring the Wander Generator for Zero Wander

b. From the Ports tab in the Ixia Anue 3500 Control Panel, double-click on the appropriate BNC port and configure the Port Properties

Figure 33: Configuring the BNC 10 MHz Output

3. For BNC ports running 2.048 MHz, use a PDH port to generate the 2.048 MHz (E1) clock, and then set the output port’s clock source to this PDH port

a. Identify a PDH port that is not going to be used for testing (e.g. pdh2). Configure this PDH port by double-clicking it from the Ports tab of the Ixia Anue 3500 Control Panel.

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Figure 34: Configuring a PDH Port to Supply 2.048 MHz Clock

b. From the Ports tab in the Ixia Anue 3500 Control Panel, double-click on the appropriate BNC port and configure the Port Properties.

Figure 35: Configuring the BNC 2.048 MHz Output

4. To use T1 or E1 over RJ48 for the outbound reference clock, configure the selected PDH port by double-clicking it in the Ixia Anue 3500 Control Panel Ports tab.

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Figure 36: Configuring a PDH Port for Outbound Reference Clock

Documents

Testing Synchronous Ethernet Wander with the Ixia · PDF file1 26601 Agoura Road Calabasas, CA 91302 Tel + 1-818-871-1800 Fax + 1-818-871-1805 P/N: 915 -6556 01 Rev. C May 2013