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  • student networking admin (need help with a project) VLSM

    Hi all Im new here to the forum and need some help with my project as im stumped. I am currently going through for "networking admin." and now in to Cisco doing a project. I had to develop an IP addressing scheme for a larger network, which consists of 56 subnets with the first subnet containing 1-32 subnets and up to 800 hosts on each, and the second subnet 33-56 with up to 12 hosts on each. I had to choose a single class A private address to accommodate all the 56 subnets (which that was easy)
    I chose 10.0.0.0 /14
    which gave me:
    10.0.0.0/14 10.0.0.1 - 10.3.255.254 and a broadcast address of 10.3.255.255
    10.4.0.0/14 10.4.0.1 - 10.10.7.255.254 and a broadcast address of 10.7.255.255
    all the way up and my last address being
    10.252.0.0/14 10.252.0.1 - 10.255.255.254 and broadcast address of 10.255.255.255

    now here is where my problem starts
    I have to use VLSM to optimize the addressing scheme by further subdividing the last subnet. I have to choose a subnet mask that will generate enough subnets to accommodate all the 24 smaller subnets I created with enough host address space to accommodte all there 12 hosts.

    so i choose 255.248.0.0 to give me 30 subnets with 524,286 hosts (of course adding the 2 to eachfor network and broadcast)
    so using my last subnet which was 10.252.0.0/14

    and my new mask of 255.248.0.0
    my results dont seem to look right to me here is what i got. Does it look right and if not can someone help to let me know where Im going wrong please and thank you, greatly appreciated

    Subnet Number Range of valid host addresses Broadcast address
    10.248.0.0 /18 10.248.0.1 to 10.248.63.254 10.248.63.255
    10.248.64.0 /18 10.248.64.1 to 10.248.127.254 10.248.127.255
    10.248.128.0 /18 10.248.128.1 to 10.248.191.254 10.248.191.255
    10.248.192.0 /18 10.248.192.1 to 10.248.255.254 10.248.255.255
    10.249.0.0 /18 10.249.0.1 to 10.249.63.254 10.249.63.255
    10.249.64.0 /18 10.249.64.1 to 10.249.127.254 10.249.127.255
    10.249.128.0 /18 10.249.128.1 to 10.249.191.254 10.249.191.255
    10.249.192.0 /18 10.249.192.1 to 10.249.255.254 10.249.255.255
    10.250.0.0 /18 10.250.0.1 to 10.250.63.254 10.250.63.255
    10.250.64.0 /18 10.250.64.1 to 10.250.127.254 10.250.127.255
    10.250.128.0 /18 10.250.128.1 to 10.250.191.254 10.250.191.255
    10.250.192.0 /18 10.250.192.1 to 10.250.255.254 10.250.255.255
    10.251.0.0 /18 10.251.0.1 to 10.251.63.254 10.251.63.255

  • #2
    Re: student networking admin (need help with a project) VLSM


    Hi...

    /18 is 255.255.192.0 subnet

    /14 is 255.248.0.0 subnet but it should give you 64 subnet with 262144 - 2 host

    I am very confused with your posting..
    Please correct me if I am wrong.. thanks guys.
    Just another MCP

    Comment


    • #3
      Re: student networking admin (need help with a project) VLSM

      Lmm, could you EDIT your post to make the numbers easier to read. Maybe spread them out a little and change the colours and/or bold them like below. (This is just a suggestion, NOT a demand)

      It breaks up the range, mask and broadcast so it makes it a bit easier to follow. Well fo my old eyes anyway.

      10.248.0.0/18 - 10.248.0.1 to 10.248.63.254 - 10.248.63.255
      1 1 was a racehorse.
      2 2 was 1 2.
      1 1 1 1 race 1 day,
      2 2 1 1 2

      Comment


      • #4
        Re: student networking admin (need help with a project) VLSM

        Hi

        THing is that you have subnetted already with 14bit mask.

        From the derived subnets, you are selecting sub network 248 to further subnetting it for VLSM


        which is not possible.

        regards

        prabu
        prabu

        Comment


        • #5
          Re: student networking admin (need help with a project) VLSM

          Hi Lmm,
          Thanks for your post!
          Did you get your question answered?
          Its good to have you in the forum!
          -David
          David Davis - Petri Forums Moderator & Video Training Author
          Train Signal - The Global Leader in IT Video Training
          TrainSignalTraining.com - Free IT Training Products
          Personal Websites: HappyRouter.com & VMwareVideos.com

          Comment


          • #6
            Re: student networking admin (need help with a project) VLSM

            Hi,

            I am not too sure but I read some where that we can not use VLSM with Subnetting. Am I right guys?

            Comment


            • #7
              Re: student networking admin (need help with a project) VLSM

              Sure, you can use both subnetting and VLSM.

              Subnetting is just taking a network and breaking it into smaller networks.

              VLSM (variable length subnet mask) just means that the subnet mask doesn't have to be fixed (like 255.0.0.0, 255.255.0.0 or 255.255.255.0). The subnet mask can be 255.255.252.0 or 255.128.0.0 or 255.255.255.224.

              Both of these work together. In networking today, you need to use both of these and they work great together.

              Thanks for your post!

              -David
              David Davis - Petri Forums Moderator & Video Training Author
              Train Signal - The Global Leader in IT Video Training
              TrainSignalTraining.com - Free IT Training Products
              Personal Websites: HappyRouter.com & VMwareVideos.com

              Comment


              • #8
                Re: student networking admin (need help with a project) VLSM

                Ahmer, further to David's post, here's a great- and free- resource for you:

                http://www.3com.com/other/pdfs/infra..._US/501302.pdf

                I've recommended this to loads of people, I've often wondered why its free!

                regards,

                theterranaut

                Comment


                • #9
                  Re: student networking admin (need help with a project) VLSM

                  Hi TT,

                  Good Doc, Thanks!

                  I will give you some reputation points for that & all your other posts!

                  -David
                  David Davis - Petri Forums Moderator & Video Training Author
                  Train Signal - The Global Leader in IT Video Training
                  TrainSignalTraining.com - Free IT Training Products
                  Personal Websites: HappyRouter.com & VMwareVideos.com

                  Comment


                  • #10
                    Re: student networking admin (need help with a project) VLSM

                    I will put my suggestion here.

                    I will use

                    /22 for the first 32 subnets with 800 hosts

                    10.0.0.0 - 10.0.3.255
                    :
                    :
                    10.0.128.0 - 10.0.131.255


                    and

                    /27 for the next 24 subnets with 12 hosts

                    10.0.132.0 - 10.0.132.31
                    :
                    10.0.132.224 - 10.0.132.255.255



                    10.1.132.0 - 10.1.132.31
                    :
                    10.1.132.224 - 10.1.132.255.255



                    10.2.132.0 - 10.2.132.31
                    :
                    10.2.132.224 - 10.2.132.255.255


                    Please correct me if I am wrong.

                    I do not know if Mr/Ms LMM will come back to take a look. But its good to have something we can practise on..
                    Just another MCP

                    Comment

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