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Please help with networking

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  • Please help with networking

    there are 5 floors in a buiding with structured cabling already done.
    The server room has a switch and patch panel. Each floor has patch and switch.From each patch panel on each floor, there is straight thru cable which runs to the patch panel in the server room. We have one computer on each floor but they cant communicate with each other.Any solutions?. The switches are D link DES 1024 and the switch on each floor is connected with straight thru cable to the its patch panel respectively(on its floor)

  • #2
    Re: Please help with networking

    Hi Shah. I'll try and give you some info but your post is a little confusing to me...

    Each jack on the patch panel that connects to another floor needs to be plugged into a switch.

    If you have done this and the computers still can't communicate then the next question is are the computers on the same subnet?

    Could you post a diagram?

    Network Consultant/Engineer
    Baltimore - Washington area and beyond


    • #3
      Re: Please help with networking


      I'm pretty good at this cabling stuff so let me give it a shot.

      First I will assume you have no subnet problems - just cabling problems.

      Next I will assume that the server room is on the 1st floor, and the other 4 floors each have a cable run from the patch panel on that floor down to the 1st floor patch panel. That means on the 1st floor patch panel you have 4 ports that come from floor 2, 3, 4 and 5. Each of these cable drops from the other floor is a "straight-thru" - meaning they are NOT wired as crossovers.

      So, the first thing to do in order to connect all 5 floors together is to connect each switch on floors 2 thru 5 to the switch on floor 1. In order to do this, you either have to use a "crossover port" on the switch or a "crossover cable" for each switch.

      Most switches today have a "crossover port" or auto-sensing ports. From your problem, I assume that none of the ports are auto-sensing ports. But you may have 1 port on each switch that is labeled as a crossover, or maybe has a little slide switch next to it that changes that one port from being a straight-thru to a crossover. Usually it is port 1 or port 24. Some switches have an extra port RIGHT NEXT TO either port 1 or 24 - that extra port is a crossover. If you have a cable plugged into that extra port, then the numbered port next to it is NOT available for use as a regular port. It is either one or the other.

      If you do not have any crossover ports on the switches, then you will need to make or buy crossover cables. (I will describe that later)

      You need 4 crossovers. The switch on floor 1 will have at most 1 crossover port (we assume they are not auto-sensing), so we will plan to do the crossover at each of the other floors. We will not use the 1st floor switch crossover port at this time.

      Here's what you do. Each PC on each floor will have a regular drop that goes to a regular port on each switch on that floor. That means on floors 1 thru 5, all the PCs, printers and network devices all can "see" each other by way of the switch on that floor.

      Then, you want to connect each switch on floor 2 thru 5 down to the switch on floor 1. Each of these connections requires ONE (1) crossover. Assuming your switches have a crossover port, plug one regular patch cable from that switch's crossover port at one end and into the patch panel port that goes to the 1st floor at the other end. On the 1st floor, plug a regular patch cable from the patch panel port for each floor into a regular port on the 1st floor switch. You should get a link light the moment you plug it in. Don't plug in to the 1st floor switch's crossover port.

      All the floors should be able to connect to the 1st floor and the server now. All the floors should be able to connect to the other floors (2 thru 5) as well. A packet from floor 2 will pass through the 2nd floor switch, then the 1st floor switch, and finally the 5th floor switch when it is going from a floor 2 PC to a floor 5 printer.

      Finally, if you do NOT have crossover ports on your switches, you can accomplish the same thing by making or buying a crossover cable for each switch on floor 2 thru 5. On a standard ethernet cable you will see the 1st 2 wires are colored white/orange and orange. The 3rd wire is colored white/green and the 6th wire is colored green.

      To make a crossover cable - swap the green for the orange and the white/green for the white/orange. If you can't do this yourself, any decent cable guy can do it for you or you can buy 4 crossover cables at a computer store.

      I would recommend MOST HIGHLY that you get cables of a different color (like RED) to use as crossover cables so that you never get fooled into using one thinking it is a regular cable. I would also mark the cable jacket at both ends in ink CROSSOVER just in case. You can "chase your tail" for days if you forget this one step.

      If you need any clarification, post again.


      • #4
        Re: Please help with networking

        One thing you need also to consider (depending on the building/fire code in your country) is the type of cable used to "link" floors. This cable can have a HUGE impact on your insurance claim if it can be determined that the cable assisted in the spread of a fire!!
        Joined: 23rd December 2003
        Departed: 23rd December 2015


        • #5
          Re: Please help with networking

          Hi Shah,

          Did you have any luck solving this or are you still looking for suggestions?

          David Davis - Petri Forums Moderator & Video Training Author
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