Cisco 3560 dropout

Posted on 2007-07-24
Last Modified: 2008-02-22
I just installed a new Cisco 3560 Gigabit 48 port switch. Since it has been installed, at least once per day the LAN seems to lose connection for a split second (or long enough for our accounting system to lose connection to the database.) which requires a restart to re-gain connection. I have started a TAC case with Cisco but for the first time I am not getting very good service from them. Are there any ideas on what I can do to determine where the problem is. I have enabled syslogging and since then I haven't experienced the problem, I estimate it will happen sometime today and when it does I want to make sure the logging is configured correctly and it will capture the needed info.
Question by:afsfire
    LVL 57

    Accepted Solution

    Make sure that only ports that carry VLAN tagged frames are setup as trunk ports.  All other ports should be setup in switchport mode access with the correct VLAN.

    LVL 17

    Assisted Solution

    Do the following:

    config t
    logging on
    logging buffered informational
    logging buffered 6
    logging buffered 32768
    logging facility local6

    Let it run until it happens again and do a "show log" and post it here. Also do you have any uplinks to other switches or is this the only switch with servers on it?

    Author Comment

    There were uplinks to 2 switches and a firewall. they had me run this on those 3 ports
    config t
    interface GigabitEthernet0/##
    no spanning-tree portfast
    wr mem

    Author Comment

    Since then I haven't had an incident so I'm thinking that the issue may be resolved... I want to wait a while longer to see if it happens again.

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