+ Post New Thread
Results 1 to 7 of 7
Wireless Networks Thread, what could be causeing this? in Technical; Welcome to Network hell part3 After lunch today i lost all conectivity on our network. Some but not all of ...
  1. #1
    e_g_r's Avatar
    Join Date
    Sep 2005
    Location
    Rochdale
    Posts
    460
    Thank Post
    51
    Thanked 26 Times in 17 Posts
    Rep Power
    24

    what could be causeing this?

    Welcome to Network hell part3

    After lunch today i lost all conectivity on our network.

    Some but not all of our switch's were flashing like mad, usual symptom of a little darling connecting 2 wall outlets with a patch cable.

    Searched high and low in all IT labs, offices, comms cabs etc but can't seem to find the loop.

    Re started switchs, tried them one by one but still no connectivity.

    Next guess spyware/virus.

    Can you get internal DofS attacks?

    Even re booted the servers.

    Left still no connectivity

    Any ideas (however mad) would be much appreciated.


  2. #2


    Join Date
    Jan 2006
    Posts
    8,202
    Thank Post
    442
    Thanked 1,033 Times in 813 Posts
    Rep Power
    341

    Re: what could be causeing this?

    enable STP on the switches.
    enable broadcast storm control on the switches
    use ethereal to monitor broadcast traffic - look for anything suspicous like a single mac address broadcasting *lots* to the network.
    yes you can DOS an internal network.

  3. #3
    e_g_r's Avatar
    Join Date
    Sep 2005
    Location
    Rochdale
    Posts
    460
    Thank Post
    51
    Thanked 26 Times in 17 Posts
    Rep Power
    24

    Re: what could be causeing this?

    Cheapskate school has just dumb switch's

  4. #4


    Join Date
    Jan 2006
    Posts
    8,202
    Thank Post
    442
    Thanked 1,033 Times in 813 Posts
    Rep Power
    341

    Re: what could be causeing this?

    probably like you suspected its a looped cable.
    check if the switches have any sort of interface at all - some dumb switches have rs232 but no web interface - you may be able to hyperterminal/minicom into them ?

    get ethereal http://www.ethereal.com/ and start looking at the traffic ( look for the broadcasts) if you know the macs of your switches you can narrow it down.
    otherwise unplug switches until it stops.
    The get some cash from the development fund....

  5. #5
    edie209's Avatar
    Join Date
    Mar 2006
    Location
    Kernow
    Posts
    705
    Thank Post
    42
    Thanked 19 Times in 18 Posts
    Rep Power
    22

    Re: what could be causeing this?

    I had alot of problems like this last year, over the summer holidays I had a company in to add more network points and they found many conections at the back of patch panels loose and some flapping around.

    This term the network has been really stable (i did upgrade all my switches though) but if it carries on its got to worth looking at for the time it could save you.

    good luck

  6. #6

    Join Date
    Jun 2005
    Location
    Preston, Lancashire
    Posts
    634
    Thank Post
    11
    Thanked 6 Times in 6 Posts
    Rep Power
    22

    Re: what could be causeing this?

    Why don't you...

    Take 1 switch out of the network at a time until it settles. Put the offending switch back into the network and remove one connection at a time until it settles - and that should lead you to the offending outlet where you might find the "looped" patch cable that maybe you missed - or something amiss on the machine connected to it?

    Maybe you've already done this.




    Andy

  7. #7
    e_g_r's Avatar
    Join Date
    Sep 2005
    Location
    Rochdale
    Posts
    460
    Thank Post
    51
    Thanked 26 Times in 17 Posts
    Rep Power
    24

    Re: what could be causeing this?

    The answer seems to be -

    a dodgy netgear switch

    2nd one this week it seems, lucky they are on 5 year warrenty.



SHARE:
+ Post New Thread

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •