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Unable to identify source of frequent STP topology change notifications

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  • 1.  Unable to identify source of frequent STP topology change notifications

    Posted Oct 17, 2018 08:54 AM

    I have a stand-alone S1500 MAS in our HS library that uplinks to a stack of  three S2500s in the nearest IDF wiring closet. The uplink port on the 2500 stack flushes the MAC addresses on it frequently (at least once a day, sometimes a couple of times a day) due to an STP topology change on one specific VLAN. This is being reported as an AirWave alert. The VLAN in question exists on the 1500, but is not assigned to any ports. The uplink between the 2500 and the 1500 is a point-to-point configuration. I'm trying to determine what would trigger this topology change notification so I can make any necessary changes, but I don't know what to look at that might tell me what is kicking off the TCN. Any ideas?



  • 2.  RE: Unable to identify source of frequent STP topology change notifications

    Posted Oct 17, 2018 10:00 AM
    Hi Jon,
    I suggest you to delete that vlan on the S1500 because there is no port assign to that Vlan in that switch. Then try to filter that Vlan on the uplink from s1500 to s2500. This could give you some time to look for a loop that maybe is causing the TCN.
    Regards
    Pedro


  • 3.  RE: Unable to identify source of frequent STP topology change notifications

    Posted Oct 22, 2018 05:14 PM

    I'm not as familiar with the Aruba switches, but am familiar with the HPE/Aruba models and a few other brands. So, I'm going to try to help but maybe there's a unique implementation of STP on these models.

     

    Are you using RSTP or MSTP? The VLAN in question, is it not applied on the uplink to the 2500 either or do you mean it's not applied to any of the access ports?



  • 4.  RE: Unable to identify source of frequent STP topology change notifications

    Posted Oct 23, 2018 08:02 AM

    Here's a visual:

     

     S2500 stack (MDF) -------- S2500 stack (IDF) ------- S1500 standalone

     

    VLAN 223 has its routed interface on the MDF switch; however, the vlan is configured (i.e., it exists and has a switching profile configured) on the other switches. It is assigned to ports on the MDF switch, not to ports on the other switches. 

    There are several other VLANs configured on the switches, but this issue of a topology change which I'm unable to identify/verify only references this particular VLAN.

    We are using Rapid PVST, not MSTP.