Identifying cat5 cables on router question

Discussion in 'Server Networking' started by Bryce, Jan 3, 2005.

  1. Bryce

    Bryce Guest


    I've gotta diagram someone's network.

    They are in a three story building.

    The rackmounted routers are on the second floor with computers on all three

    Probably about 40 computers.

    I've gotta identify which cat5 goes to which computer. Whoever set this up
    never labled the cables.

    What would be the best way to do this other than unconnecting one cable from
    the router and running around the whole building to find out which computer
    isn't on the network anymore?

    Thanks for any suggestions.

    Bryce, Jan 3, 2005
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  2. Bryce

    CyberDroog Guest

    A "tone and probe" tool. You connect the client end of the cable into a
    small device, then use the probe at the router end to tell you which cable
    the device is on (it emits a tone when you come near the proper cable.)

    Something like this:

    You don't have to buy from anyone. You don't have to work at any
    particular job. You don't have to participate in any given relationship.
    You can choose.

    - Harry Browne
    CyberDroog, Jan 3, 2005
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  3. Depending on the router / switch, you should be able to
    use the software console to resolve tcp/ip addresses to
    each port then use nbtstat -A against the tcp/ip address
    to get the computername..
    Michael Giorgio - MS MVP, Jan 3, 2005
  4. A phone technicians trick but involves running up and down
    three flights multiple times..
    Michael Giorgio - MS MVP, Jan 3, 2005
  5. Bryce

    Jeff Cochran Guest

    So use a network cabling tool that detects multiple cables.
    Everything from Lanmeters to stand alone cable tracing equipment has
    numbered end plugs available now.

    Though you should be able to narrow it down a little by where the
    cable runs.

    Jeff Cochran, Jan 4, 2005
  6. Bryce

    .:mmac:. Guest

    how about setting an IP scanner up (gfi languard comes to mind but there may
    be other choices) and have it run through the IP range, disconnect a cable
    and run it again, label the one that doesn't respond and then use that IP to
    determine the pc name and then label accordingly. Depending on DHCP usage
    and lease duration, the IP should stay put long enough to conduct the test.
    .:mmac:., Jan 4, 2005
  7. More than one way to skin the cat so to speak. <g>
    Michael Giorgio - MS MVP, Jan 4, 2005
  8. Not if you convince someone else to help you, and use cell phones/walkie
    talkies! :)
    Lanwench [MVP - Exchange], Jan 4, 2005
  9. Bryce

    Bryce Guest

    Thank you everyone. I will try these things.

    Bryce, Jan 4, 2005
  10. Agreed but there are so many port scanning tools available
    I would forget about the manual process.

    "Lanwench [MVP - Exchange]"
    Michael Giorgio - MS MVP, Jan 4, 2005
  11. What does a port scanner have to do with it.
    Phillip Windell, Jan 5, 2005
  12. First they wouldn't connect to a router, they would connect to a hub or
    switch (unless you run a layer3 switch)

    Use two people. One stands by the switch and watches the LEDs. The second
    person unplugs the PC at the other end while the first person takes note of
    which LED goes out.
    Phillip Windell, Jan 5, 2005
  13. There are tools which scan the ports on the switch to determine
    the tcp/ip address e.g., Intel Device View's vlan monitoring feature
    spits out the MAC address along with tcp/ip address for each port
    Michael Giorgio - MS MVP, Jan 5, 2005
  14. Well, technically speaking, each floor could be on it's
    own segment.
    A bit Neanderthal to say the least but effective..
    Michael Giorgio - MS MVP, Jan 5, 2005
  15. IP#s and MAC addresses won't help to know where the cables physically run.
    It is the "physical world" vs the "logical world".

    Now if all machines have static address and records exist or are created for
    that, then I can see that being helpful, but if they are using DHCP that
    would not help much.
    Phillip Windell, Jan 5, 2005
  16. Doesn't matter, it is still the same idea. With more complex networks you
    must begin at the Hub/Switch closest to the machines and work your way back
    to the MDF. Every cable will have to be labled whether it is between
    machines and hubs, hus & hubs, hubs & switches, whatever. But the process
    is the same, watches the hub/switch to see which LED goes out when a
    cable at the other end is briefly unplugged.

    There isn't going to be any sitting in the Admin's Easy-Chair, people are
    going to have to get up and walk. Someone is also going to have to
    physically write or print out the cable lables and put them on the cables.
    Phillip Windell, Jan 5, 2005
  17. Bryce

    Jeff Cochran Guest

    MAC addresses identify a physical system. All you need now is
    diagram of where each MAC address is located in your building. :)

    Jeff Cochran, Jan 6, 2005
  18. Reread the original post Phillip. The task is to find which RJ 45 port
    runs to
    which computer. Regardless of DHCP the tcp/ip address will yeild the
    computername using nbtstat.
    Michael Giorgio - MS MVP, Jan 6, 2005
  19. You certainly can do this without physically being at each end.
    If you are saying its not possible that's fine but I disagree

    Part of being an admin is finding easier ways to do things e.g.,
    to change the local admin password on all clients you certainly
    don't visit each and every client do you?

    Michael Giorgio - MS MVP, Jan 6, 2005
  20. The quickest most time effecient way to do this would be use a network tool
    and tone it out at the patch panel. This is something that should have been
    addressed when the netowork was initially setup. I have been in on some ugly
    data rooms that look like a big ugly spaghetti mess with cables running
    everywhere, it took months to get everything cleaned up. Certainly several
    hours of laying out and labeling things, then making sure people follow
    SOP's for connecting machines would have saved us time and money.
    Eugene Taylor, Jan 6, 2005
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