Wireless Point-to-Point Troubleshooting Guide

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Updated:October 23, 2018
Document ID:14242

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    Introduction

    This document is an aid to troubleshoot wireless connections.? The first steps to take is to answer the questions in this document to become familiar with what kind of wireless link you use, and with what type of equipment.? From there, you can proceed to the chart and perhaps find your possible problem and the necessary steps to take to resolve the issue.

    Prerequisites

    Requirements

    There are no specific requirements for this document.

    Components Used

    This document is not restricted to specific software and hardware versions.

    The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

    Conventions

    Refer to Cisco Technical Tips Conventions for more information on document conventions.

    Where is the Potential Problem?

    When you troubleshoot wireless connections, consider these questions:

    • What type of link is this??

      • Microwave Multi-point Distribution System (MMDS)

      • Unlicensed National Information Infrastructure (UNII)?

        Refer to Unlicensed Frequencies.

    • How far is the link? (miles)

    • Is the link a line-of-sight link?? If yes, how do you know??

    • If this is a UNII link, check for interference as a higher priority on your checklist.

    • What is the antenna size?? Gain?? Is the antenna properly polarized?

      Refer to Antennas.

    • What is the cable length from the transverter to the antenna?? What type of cable?

      Refer to Cable and Connector Loss.

    • Are there other antennas close to yours?? If so, can you determine if they emit signals that cause you an interference problem? The mere proximity of other antennas generally does not pose a problem if:

      1. The antennas do not emit signals that can interfere with yours; and

      2. The antennas are not within your path axis.

    For additional help with these questions, see the "Related Information" section.

    Status Line Condition

    Radio x is Up -- Line Protocol is Up

    Possible Problems Checks & Observations Solutions Comments
    --------- --------- This is the proper status line condition. No action is required.  

    Radio x is Up -- Line Protocol is Down

    Possible Problems Checks & Observations Solutions Comments
    Interference Run histograms and/or snapshots; measure SNR and Rx signal level at both ends of the link Try to locate source of interference (for example, nearby antennas) Change polarization of antennas or frequency channel (UNII only) If interference is the source of trouble, the SNR readings must show a degradation that correlates in time with the noted periods of poor link performance or outages
    Poor (weak) receive signal level Check antenna alignment Check cable/connector integrity (possible moisture in cables) Check transmit power level for the link Check for path blockage of link (for example, trees, buildings, etc.) Change bandwidth and throughput setting Replace faulty cables if necessary Reconfigure Tx power setting if necessary Realign antennas Change the throughput setting as a work-around. Only change throughput settings after you try the other solutions given.
    Loopback enabled Check the configuration and issue the show run and show interface radio slot/port commands Disable loopback command  
    Incorrect throughput setting Check the configuration, and issue the show run command Run a histogram to check the SNR -Adjustthroughput setting accordingly This parameter must be set the same at both ends of the link
    Faulty control cable connection; Check all control cable connections; wiggle suspected control cable while you monitor link status to verify faulty connection Replace cable or connections if necessary  

    Radio x is Down -- Line Protocol is Down

    Possible Problems Checks & Observations Solutions Comments
    Radio interface shutdown Check the configuration and issue the show interface radio slot/port command No shut the radio interface Note that if this is the problem, the output of show interface will display "Radio x is administratively down"
    Interference Run histograms and/or snapshots; measure SNR and Rx signal level at both ends of the link Try to locate source of interference (for example, nearby antennas) Change polarization of antennas or frequency channel (UNII only) If interference is the source of trouble, the SNR readings must show a degradation that correlates in time with the noted periods of poor link performance or outages
    Wireless line card faulty Run IF and RF loopback tests and ping the radio interface to verify Replace line card  
    Frequencies configured incorrectly Check configuration, and issue the show run command Fix the configuration; Tx at one end of the link matches to the Rx of the other end  
    Radio ARQ configured incorrectly Check the configuration, and issue the show interface radio arq command Fix the configuration This parameter must be set the same at both ends of the link
    Number of antennas set correctly Check the configuration and issue the show run command Fix the configuration  
    Incorrect throughput setting Check the configuration; measure the SNR -Adjust the throughput setting accordingly This parameter must be set the same at both ends of the link
    Radio privacy set the same on both sides Check the configuration, and issue the show run command Fix the configuration This parameter must be set the same at both ends of the link
    Transmit power configured incorrectly Check the configuration, and issue the show run command Fix the configuration, and set radio transmit power to a valid value for the link  
    No power to one or both transverters (ODUs) Use a voltmeter to check DC voltage at input to PFPs Check that DC breaker switches on PFPs are turned on Repair/replace DC power supplies Turn on breaker switches on PFPs  
      Check cable integrity and connections Ensure that cable is 50 ohm type Run debug radio log verbose Replace the cable if necessary Be sure all outdoor connections are properly sealed, only use Coax-Seal or an equivalent
    Control cable between PFP and transverter bad or disconnected Check cable integrity, especially cable-to-LEMO connector junction Run debug radio log verbose Replace the cable if necessary Weather proofing not required for LEMO connector
    Poor or no receive signal level Verify by measuring SNR from histograms Be sure antennas are set for the same polarization Be sure the antennas are aligned properly Check all cabling, IF and RF Have both sides of the link with the same polarization (horizontal or vertical) Align the antennas Replace the cables if necessary  
    Incorrect duplexer installed Check the sticker on duplexer at each end of the link to ensure both ends are for the same band plan   Duplexers cannot be re-tuned, they must be replaced
    Incorrect duplexer set-up Duplexer at one end must be installed for tx high and the other side for tx low Remove, reverse, and reinstall ONE of the duplexers  
    ODU not detected Run IF loopback test, ping radio interface to verify whether the line card is good Run debug radio log verbose to verify the problem Replace ODU  

    Related Information

    Revision History

    Revision Publish Date Comments
    1.0
    23-Oct-2018
    Initial Release

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