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Clients disconnecting randomly with WLC and ACS




    In this document Cisco TAC engineer "Varun Ajmani" has explained how to troubleshoot when Clients disconnecting randomly with 5508 ( authentication issues with SSID's using Ldap via an ACS server.

    Problem Description

    • WLC running (all six controllers are facing same issue)
    • SSID using 802.1x, ACS (PEAP-MSCHAPv2) with Active Directory
    • All domain users are getting de-authenticated. Machines have “user or machine authentication” selected when the issue occurs, once they
    • change it to “machine authentication” or reboot the machine, the issue is resolved.

    Errors on ACS

    *15039 Selected Authorization Profile is DenyAccess
    *Radius authentication failed for USER: DISTRICT\testuser  MAC: 84-4B-xx-xx-xx-xx  AUTHTYPE: PEAP(EAP-MSCHAPv2)
    *Radius authentication failed for USER: DISTRICT\testuser  MAC: 84-4B-xx-xx-xx-xx  AUTHTYPE: PEAP(EAP-MSCHAPv2)*Radius authentication failed for USER: DISTRICT\testuser  MAC: 84-4B-xx-xx-xx-xx  AUTHTYPE: PEAP(EAP-MSCHAPv2)*24423  ACS has not been able to confirm previous successful machine authentication for user in Active Directory
    *11003  Returned RADIUS Access-Reject


    The aging time in ACS for End user authentication settings was set to 12 hours. We need to increase the timer to have the users connected throughout.

    End User   Authentication Settings

    End User   Authentication Settings

    Enable Machine Access Restrictions

    Click to ensure that machine authentication results are tied   to user authentication and authorization. If you enable this feature, you   must set the Aging time.

    Aging time (hours) time

    Time after a machine was authenticated that a user can be   authenticated from that machine. If this time elapses, user authentication   fails.

    You must set this   time if you clicked the Enable Machine Access Restrictions check box.

    Machine Authentication

    ACS supports the authentication of computers that are running the Microsoft Windows operating systems that support EAP computer authentication. Machine authentication, also called computer authentication, allows networks services only for computers known to Active Directory.

    This feature is especially useful for wireless networks, where unauthorized users outside the physical premises of your workplace can access your wireless access points.

    When machine authentication is enabled, there are three different types of authentications. When starting a computer, the authentications occur in this order:

    • Machine authentication—ACS authenticates the computer prior to user authentication. ACS checks the credentials that the computer provides against the Windows identity store.
    • User domain authentication—If machine authentication succeeded, the Windows domain authenticates the user. If machine authentication failed, the computer does not have access to Windows domain services and the user credentials are authenticated by using cached credentials that the local operating system retains.
    • User network authentication—ACS authenticates the user, allowing the user to have network connectivity. If the user exists, the identity store that is specified is used to authenticate the user.

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