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  • SF300 ports flapping

    I'm in the tail end of a move from one office to the other.
    The 2x Cisco SF300 and 1x Cisco ESW500 switches were fully reset to defaults.
    I've been unable to access the ESW500 (I suspect this is the one being problematic)

    Ports keep flapping - they'll shut down for 30 seconds or so.
    sometimes they'll just shut down and won't come back up

    There's no port security in palce - I already disabled all of that

    I'm at a bit of a loss because it's all brand new cabling from the patch ports to the switch..
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  • #2
    Re: SF300 ports flapping

    How is the layout? What trunks are in place? BPDU guard enabled?
    CCNA, CCNA-Security, CCNP
    CCIE Security (In Progress)

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    • #3
      Re: SF300 ports flapping

      Cisco 881 FE0 to ESW500 GI1
      Cascaded cat6 cable from ESW500 GI2 to SF300-1 GI1
      Cascaded Cat6 cable from SF300-1 GI2 to SF300-2 GI1
      Cascaded Cat6 cable from SF300-2 GI2 to another 10/100 unmanaged switch

      no trunks configured - it's all a single, flat vlan

      not sure where I'd enable BDPU guard - however STP is disabled on both the SF300s at both interface and global level
      If I check the STP interface settings, it says BPDU handling is floodig though


      no QoS or access control in place, no port lock

      thanks for your help so far
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      • #4
        Re: SF300 ports flapping

        Even thought its a single flat network I would still run spanning tree just as a precaution. Enabling spanning tree will not produce any adverse affects either. If you want redundant links between your switches then use etherchannel (portchannel) A spanning tree loop can cause all kinds of issues. I would enable it and if your switch supports it run rapid spanning tree which will give u sub second convergence. Spanning tree also gives you an election of your root switch, which should be the higher grade platform. If its not a loop then double check your cabling, look for bad nics on your clients etc. .Its very possible you have a bad switch as well. Isolate it and troubleshoot from there.
        Last edited by auglan; 16th April 2013, 12:33.
        CCNA, CCNA-Security, CCNP
        CCIE Security (In Progress)

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        • #5
          Re: SF300 ports flapping

          i already thought it was a bad switch.. i have a new 48x coming (they needed more ports anyway) so I'll swap it out and see. At least I can configure it then :P
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          • #6
            Re: SF300 ports flapping

            i already thought it was a bad switch.. i have a new 48x coming (they needed more ports anyway) so I'll swap it out and see. At least I can configure it then :P
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            • #7
              Re: SF300 ports flapping

              turned out to be Green Ethernet as best we can tell - i've had no more reports of ports dropping out after turning that off (and putting in a new switch.. but we'll see)
              the voice auto-vlan did screw me over a bit though :P
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