Keysight N4891A 400GBASE User Manual
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Keysight N4891A 400GBASE User Manual

Fec-aware rx test solution
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Keysight N4891A 400GBASE
FEC-Aware Rx Test Solution
User Guide

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  • Page 1 Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 2 DFARS and are set forth specifically in Manual Part Number or loss of important data. Do not pro- writing elsewhere in the EULA. Keysight ceed beyond a CAUTION notice until the N4891-90119 shall be under no obligation to update, indicated conditions are fully under- revise or otherwise modify the Software.

  • Page 3: Table Of Contents

    3 Using the KiOS Interface for the N4891A Solution Accessing the KiOS interface Landing Page Line Speed Control Port Settings Mode BERT Host QSFP-DD Statistics page BERT statistics page FEC Statistics Page eBERT Statistics CMIS Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 4 Loopback Configuration—BERT mode Checking BER on STATS View Setting FEC-aware Mode Loopback Configuration—KP4 FEC-aware mode Synchronizing with M8040A Receiver Compliance Testing Jitter Injection Using the M8070B DUT Control Interface Testing 100G/l Optical Interfaces Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 5 Contents Troubleshooting Scenario 1: Link is not up in BERT mode Scenario 2: Link is not up in KP4 mode, BERT mode works as intended Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 6 Contents Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 7: Introduction

    Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide Introduction Safety Issues / Introduction to the N4891A Solution / Specifications /...

  • Page 8: Safety Issues

    Touch Current from Coaxial Cables Connect the shield coaxial cables to building earth in accordance with applicable local, national, and international electrical codes. Fan Instruction Moving fan blade. Keep body parts away from fan blades. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 9: Introduction To The N4891A Solution

    N4891A 400GBASE FEC-aware Receiver Test Solution When used in combination with the Keysight M8040A, the N4891A offers a unique 400GBASE FEC-aware Receiver Test Solution. This solution enables measurement of frame loss ratio in 400G Ethernet links using FEC by supplying one stressed lane, while maintaining the proper FEC striped test pattern data.

  • Page 10: Specifications

    IEC 60950-1, UL 60950-1, CSA C22.2 No.60950-1, IEC 62368-1, UL 62368-1, CSA 62368-1, CE (LVD, EMC, RoHS), EN/IEC 55032, EN/IEC 55024, CFR 47, FCC Part 15B, ICES-003, AS/NZ CISPR 32/24, KN32/35 Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 11: Getting Started With The N4891A Solution

    Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide Getting Started with the N4891A Solution Chassis Setup / Front Panel Overview / Controlling the Equipment / Installing License /...

  • Page 12: Chassis Setup

    To mount the N4891A chassis on a bench, install the four rubber feet to the bottom of the unit, one at each corner, using the supplied screws. Refer to Figure Figure 1 Illustration for bench mounting the N4891A chassis Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 13 Install the mounting ears (one at each corner). Insert the N4891A chassis into the rack and fasten the ears to the rack. Figure 2 Illustration for bench mounting the N4891A chassis Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 14: Front Panel Overview

    • 4 USB: 2 USB 2.0 + 2 USB 3.0 ports • 1 RJ45: 1000/100/10Mbps Ethernet management port • 1 Display Port supporting a maximum resolution of 4096 x 2304 @60Hz Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 15: Controlling The Equipment

    Note the IP address from the Linux OS attributes. Figure 3 Finding IP address using the web browser • Console window: Launch a console window on the N4891A chassis. ii Use the ifconfig command to display the IP address. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 16: Configuring The Hostname

    <host name> Setting up the N4891A solution The setting up of the N4891A 400GBASE FEC-aware Receiver Test Solution requires following additional steps: Connect the ‘Clock Out’ of the N4891A chassis to the ‘Ref CLK In’ of the M8045A pattern generator.
  • Page 17 Getting Started with the N4891A Solution Figure 4 Connection diagram sample for the N4891 solution Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 18: Installing License

    On the License Manager page, click the MyKeysight.com link at the top of the page. Login to the Keysight website, and download your license file. On the License Manager page, select Add New License. Select Choose File, then select the license file.
  • Page 19 Description of the licensed feature. Version Version of the licensed feature. Expiration Date and time that the license shall expire. Type Type of license. Count Number of licenses installed. Filename Name of the license file. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 20 Getting Started with the N4891A Solution Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 21: Using The Kios Interface For The N4891A Solution

    Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide Using the KiOS Interface for the N4891A Solution Accessing the KiOS interface / Line Speed Control / Port Settings / Statistics page / CMIS / Menu Options /...

  • Page 22: Accessing The Kios Interface

    6. The “Landing” page is the top-level page in the software. Figure Figure 8 Figure 9 describe the various components on the page. Figure 6 Main components of the landing page Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 23 Using the KiOS Interface for the N4891A Solution Figure 7 Landing page components (top-right corner) Figure 8 Landing page components (bottom) Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 24 Using the KiOS Interface for the N4891A Solution Figure 9 Landing page components (left) Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 25: Line Speed Control

    Enables you to change the line speed of all ports in the chassis. This affects only the ports running in “KP4 FEC” mode (see “Port Settings" on page 26 and “FEC Statistics Page" on page 34). Figure 10 Line Speed Options Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 26: Port Settings

    Select the area of the port settings (Mode, BERT, or Host QSFP-DD) that you want to configure. Configure the selected settings. Refer to the further sections for more information regarding configuring each setting. Click Apply to save any changes. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 27: Mode

    Depending on the selected line speed, one of the following: • KP4 FEC (400GE) • KP4 FEC (2x200GE) • KP4 FEC (4x100GE) • KP4 FEC (8x50GE) Note: In eBERT mode, the KP4 option is not available. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 28: Bert

    If you select Auto-Detect, KiOS automatically identifies the incoming pattern. • If you select a specific pattern, KiOS discards any traffic that does not match the selected pattern. Rx Invert If enabled, the received pattern is inverted. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 29: Host Qsfp-Dd

    Use the sliders to change the settings. SerDes Lanes Current settings of each SerDes lane along with the set value for each port. The options are: • Pre-cursor 2 (dB) • Pre-cursor (dB) • Driver Amplitude (mV) Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 30 • ModPrsL — Indicates when the QSFP-DD is always reported as present (inserted) or not. • The non-editable parameters ModState and IntL indicate the current sate of the QSFP-DD module and if the status is currently being changed. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 31: Statistics Page

    Next to the duration, the current status of the port displays (Running, Stopped, or Paused). Refer to Figure Figure 15 Buttons available in Stats page (for both BERT and FEC mode) Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 32 This is the NRZ Bit Error Ratio. This attribute displays the Ratio of error bits to total bits transmitted, in the format 0.00E0. Pattern Lock Lost Count Number of times pattern lock has been lost (equivalent to sync loss seconds in a BERT system). Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 33 Mismatched 1’s Ratio Ratio of erroneous ones to received ones. Pattern Lock Lost Count Number of times pattern lock has been lost (equivalent to sync loss seconds in a BERT system). Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 34: Fec Statistics Page

    Stats page and FEC Lane Stats page, respectively. The buttons shown for FEC statistics work in the same manner as that for BERT statistics. Refer to Figure Figure 18 FEC Codeword statistics page Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 35 11. The Codewords All Ports button displays FEC statistics for all ports that are in KP4 FEC mode. The statistics displayed by the Codewords All Ports button are illustrated in Figure Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 36 Per IEEE 802.3bs, the N4891A has two FEC engines. If either FEC engine or both FEC engines detect an uncorrectable codeword at the same time, that counts as one event. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 37 Indicates whether or not the virtual lane (VL) is locked to the alignment marker. • Gray = locked • Yellow = lock previously lost, but is currently locked • Red = lock lost Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 38: Ebert Statistics

    SSPRQ100/SSPRQ50 BERT Patterns: Patterns composed of a repeating PAM4 symbol sequence and intended for optical Tx testing. SSPRQ patterns are stressful, but short enough to use for advanced analysis of equalization, jitter/noise analysis, etc. SSPRQ patterns are defined in IEEE802.3BS. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 39 Burst errors are configured by parameters on the Port Settings page. • BERT Inferred FEC: BERT Inferred FEC (BIF) is a feature that displays FEC statistics in real time based on the BER errors. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 40: Cmis

    Read, the page reads the current register value. For the registers that include a field in the Write Hex column, you can enter a value, select Write, and change the register value. Selecting Refresh updates all the values on the page. Figure 22 CMIS 3.0 interface Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 41 Using the KiOS Interface for the N4891A Solution Figure 23 CMIS 4.0 interface Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 42 New hexadecimal value to be written to the register Write Binary Binary expression of the new hexadecimal value to be written to the register Write Writes value in the Write Hex field to the register Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 43: Menu Options

    You can import and export the test plan as a single file. The Test Reports page contains the controls to create, run, and manage the tests, and it shows the test status during a test run. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 44: System Admin

    System Admin displays ‘4 Ports’ as 4P, ‘-KP4 option’ as FEC and ‘-SYC option’ as SYNC, and ‘-BRT option’ as EBERT. To display the System Admin page, select Menu | System Admin. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 45 Using the KiOS Interface for the N4891A Solution Figure 26 Interface for ‘System Admin’ (A400GE-QDD) Figure 27 Interface for ‘System Admin’ (Linux OS) Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 46: System Logs

    To display the System Logs page, select Menu | System Logs. Real Time Log messages To display the log messages from the N4891A chassis, click Real Time Log. Figure 28 System Logs (Real Time) Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 47: Software Update

    Software already installed on the N4891A chassis. Local drive Software stored on the PC where your browser is running. Cloud server Keysight's cloud server. To display the Software Update page, select Menu | SOFTWARE UPDATE. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 48 The software file is transferred from the PC to the N4891A. After the transfer is complete, the N4891A then displays it in the list of installed software. Click Start to begin using the new software package. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 49: License Manager

    N4891A chassis restarts. Ensure that you have the license details available before you perform a system restore. You must install a license before you can use the N4891A chassis. To display the License Manager page, select Menu | License Manager. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 50 On the License Manager page, click the MyKeysight.com link at the top of the page. Login to the Keysight website, and download your license file. On the License Manager page, click Add New License. Click Choose File, then select the license file.

  • Page 51: Help

    M8040A BERT analyzer require feature activation codes, which you can obtain from Keysight Licensing Management. To enable a feature, you must enter an activation code in the Feature Activation section.
  • Page 52 Using the KiOS Interface for the N4891A Solution Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 53: Testing Optical Transceivers

    Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide Testing Optical Transceivers About Optical Transceivers / Basic Functional Testing /...

  • Page 54: About Optical Transceivers

    For optical transceivers that require more power per port, contact Keysight Support for further information. For optical transceiver modules, Keysight recommends the use of the Optical Defaults settings, which have been tested across a variety of vendor optics. The transmit pre-emphasis settings shown in Table 16 are provided as a guide for establishing a baseline for optical transceiver support.

  • Page 55: Basic Functional Testing

    Testing Optical Transceivers Basic Functional Testing Workflow Procedure Plug the transceiver under test (also referred to as the DUT) in one port of the N4891A and verify on the “Landing” page that it is correctly recognized. Connect the DUT in optical loopback or connect its optical interface with the corresponding interface (refer to Case 2 shown in Figure 39) of the second reference transceiver plugged into a...
  • Page 56 Testing Optical Transceivers Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 57: Fec-Aware Receiver Testing

    Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide FEC-aware Receiver Testing Hardware & Software Requirements / Setup Configuration / Setting PRBS Mode / Setting FEC-aware Mode / Receiver Compliance Testing / Troubleshooting /...

  • Page 58: Hardware & Software Requirements

    To verify if the mandatory options have been installed, click the menu icon on the right side corner of the GUI, click SYSTEM ADMIN, and check the Options field in the Status table. Figure 37 Checking Options in the KiOS table Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 59: M8070B Requirements

    Keysight 83059A) are required to connect the recommended QSFP-DD HCB-Tx and MCB. Recommended Port setup In order to limit the mechanical stress on the MCB and HCB adapters, Keysight recommends not to use adjacent ports on the N4891A chassis for the FEC-aware testing. Therefore, in this document,...
  • Page 60 FEC-aware Receiver Testing • Port 1 used as Tx (HCB Tx adapter) • Port 4 used as RX (HCB Rx adapter or loopback module) Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 61: Setup Configuration

    Complete all connections with the M8040A BERT and the N4891A CAUTION chassis powered off. Figure 38 Case 1: FEC-aware connection setup for electrical receiver test Figure 39 Case 2: FEC-aware connection setup for optical receiver test Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 62: Procedure

    10 Power up the N4891A chassis, the M8040A and the MCB. The MCB module should be detected by the N4891A. If not, it may need to be reset. Refer to “Troubleshooting” on page 74 for more information. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 63 On a Windows-based machine, click Start > Keysight M8070B. • If the installed version of the M8070B is higher than 7.5, click Start > Keysight M8070B • Select the FEC mode corresponding to your application (50G, 100G, 200G, 400G) Figure 41 Starting 400G mode in M8070B (v7.5 or above)
  • Page 64 Set the Pattern to a PRBS sequence (such as, PRBS13Q). Note that the N4891A receiver does not support SSPRQ pattern. Set Global Outputs of the M8070B to ON and uncheck the Enable Impairments check box. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 65: Setting Prbs Mode

    Rx adapter). For optimum settings, selecting Electrical Defaults or Optical Defaults, as appropriate, is considered a good starting point. Refer to Table 18 “Troubleshooting” on page 74. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 66: Checking Ber On Stats View

    • On the M8070B software, adjust the de-emphasis setting of the M8040A Channel 1 Data Out. Suggested settings are: • Coefficient 1: -0.03 • Coefficient 2: -0.05 • Amplitude: 300 mV to –500 mV Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 67: Setting Fec-Aware Mode

    The scrambled idle pattern is not supported by the M8040A error detector NOT E (M8046A) or the AWG product family. Therefore, only the M8045A pattern should be adjusted, as shown in Figure 46 Figure 46 Adjusting pattern on M8045A Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 68: Synchronizing With M8040A

    • BER should be visible for all 16 PCS lanes (each electrical lane includes 2 PCS lanes – LSB and MSB). Note that it may take up to a minute for the digital equalizer of N4891A Rx port to adapt to the new lane. Refer to “Troubleshooting” on page 74. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 69 • Switch to FEC Codewords Stats view. Click Port 4 > STATS > FEC Codewords to view the FEC performance of the link including pre-FEC BER, post-FEC Frame Loss Ratio and FEC Codeword error distribution. Figure 50 Sample FEC Codewords Stats for Port 4 Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 70: Receiver Compliance Testing

    Refer to the user guides for the respective applications for more information regarding the stress signal calibration procedures and equipment requirements. In general, following is the procedure for device testing with the N4891A 400GBASE FEC-aware Receiver Test Solution: Choose the appropriate compliance application.

  • Page 71: Jitter Injection

    Change this value if required. Figure 52 Setting RJ Parameters Ensure that the Enable Impairments check box is checked to activate impairment sources. Figure 53 Verifying Enable Impairments selection Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 72: Using The M8070B Dut Control Interface

    53 Gbaud PAM4 signal generated on Pattern Generator 1 or Pattern Generator 2 includes all the 100G-KP4 PCS lanes (0,1,2,3) and corresponds to the two multiplexed 50G PAM4 tributaries of the 100GAUI-2 interface. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 73 FEC-aware Receiver Testing λ Figure 55 Principle of 100G/ FEC-aware testing Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...

  • Page 74: Troubleshooting

    – if that is not the case, connect a wire from MPL to GND on the HCB Tx Adapter’s low speed connector. If the HCB Rx Adapter is also being used, it will be necessary to connect MPL to Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 75 If these lanes do not come from the BERT, then unplugging and plugging back the reference module (or Rx adapter) on the receiver port will force the equalizer initialization. Wait up to 2 minutes for all the lanes to turn green. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 76 • Wait for up to a minute Symptoms: Numerous burst errors in FEC mode, “VL Lock Lost” counter very high for stress lane • Try to re-sync by clicking Sync • Try the next point Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 77 • Check / measure the input frequency again. (See Figure 58). Figure 57 Checking Expected and Detected Clock Frequency Figure 58 Checking Input Frequency in M8070B software Multiple incorrect default settings for the Clock. Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 78 FEC-aware Receiver Testing Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 79 Keysight N4891A 400GBASE FEC-Aware Rx Test Solution User Guide...
  • Page 80 This information is subject to change without notice. © Keysight Technologies 2021 January 2021 www.keysight.com...

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