Wireless Access

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Access network design for branch, remote, outdoor, and campus locations with HPE Aruba Networking access points and mobility controllers.
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FCS error on the switch side and phones inbound voice bad quality

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  • 1.  FCS error on the switch side and phones inbound voice bad quality

    EMPLOYEE
    Posted Jun 23, 2020 02:58 AM

    Hi,

      I am running 8.5.0.0 and for some reason my Cisco phone are not working, especially, incoming voice. Same configuration on the phone works fine with Cisco AP. After checking I notice that I have a high FCS error rate on the switch port where Aruba APs are connected. I am using AP 535. Any advice would be highly appreciated. Worth to mention that all traffic are DSCP-EF marked end-to-end and my role for the VIOP SSID is Aruba default voice role. MTU size are default on the Aruba controller and the switch which is 1500.  



  • 2.  RE: FCS error on the switch side and phones inbound voice bad quality

    EMPLOYEE
    Posted Jun 23, 2020 07:25 AM

    There is not enough information to determine what your issue is.

     

    FCS errors could mean bad cabling.  Are you sure those errors are not "giants", which is typical of AP path mtu discovery?

     

    When you type "show datapath session table <ip address of phone>" do any of the flows have the voice flag?  

     

    There are many things to check with your setup.  You might want to open a technical support case in parallel to this post.



  • 3.  RE: FCS error on the switch side and phones inbound voice bad quality

    EMPLOYEE
    Posted Jul 08, 2020 10:22 PM

    Hi,

      I just want to update everyone as other people might run to this issue in the feature. When it comes to FCS error, you will need to reduce the MTU size from 1500 to something like 1300. 

    When it comes to the Cisco 8821 phone, you will need to turn off the power saving mode in the phone itself NOT from the call manager. AP 5xx will not work with this phone if the power saving mode enabled and will cause call drops.