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  • Change Network IP Range

    Hi Guys,
    My company is using a domain IP range of 190.100.x.x which is not a private IP range. I want to change this to a private one namely 192.168.100.x
    But this is going to be a lot of work because we have the following:
    aprox 100 clients; switches, routers, servers, internet banking system, website, printers, dmz zone, ATMís and a remote site. We are planning for a new branch and are going on VoIP. I donít want to use the old IP range for the new branch neither the VoIP system.
    What is the best way to do this in a short period?

  • #2
    Re: Change Network IP Range

    So all of your hosts and equipment are assigned public ip's? Not going to be any easy solution to this. The clients shouldn't be an issue as you can just create a new dhcp pool with the private range you need. The routers and switches would have to be done manually of course. You can use secondary ip addressing on the routers if they support it. What about routing protocols as those would have to be changed as well as far as whats being advertised. You can keep whatever hosts you have in the dmz with public ip addressing if you like or switch them over to a different subnet. You also have to look at new nat translations etc. Personally I would start with the network equipment first as that will be the most time consuming. Depending on how many routers/switches you have you can knock it out after hours during the night. Just have a good plan in place with a structured approach.
    CCNA, CCNA-Security, CCNP
    CCIE Security (In Progress)

    Comment


    • #3
      Re: Change Network IP Range

      Switches and printers can be done through DHCP Reservations. That will save you having to enter new IPs in each one of them.

      Servers can be prepped in advance by adding a second IP to the NIC so they will work on the new Range when the new DHCP is Authorised though I have not found it necessary to use this idea.

      It may look like a big job but having done many IP Range changes in the last few years it is really quite simple if you write up a plan well before the change and prepare as much as you can in advance and be throughly familiar with what needs to be done. Suggest you have a printed checklist so you can tick off each change as it is done so nothing is forgotten.

      When are you planning to undertake this change?
      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: Change Network IP Range

        This biggest "gotcha" I've encountered when doing this is when the following list references IP addresses instead of hosts or FQDNs:
        - scripts
        - shortcuts
        - links in docs and spreadsheets
        - data sources
        - configurations in LOB applications
        - customizations and in-house programs

        Doing the actual change on the equipment is the easy part. Going through and finding the above issues is the hard part. Be sure to take the non-networking aspects into account.
        Regards,
        Jeremy

        Network Consultant/Engineer
        Baltimore - Washington area and beyond
        www.gma-cpa.com

        Comment


        • #5
          Re: Change Network IP Range

          It sounds interesting but I'm a little afraid of the time frame.

          Comment


          • #6
            Re: Change Network IP Range


            Originally posted by Engelmar View Post
            It sounds interesting but I'm a little afraid of the time frame.
            I'm not sure what you're referring to.
            Regards,
            Jeremy

            Network Consultant/Engineer
            Baltimore - Washington area and beyond
            www.gma-cpa.com

            Comment


            • #7
              Re: Change Network IP Range

              I mean is it possible to finish all this in a week or two? I must make a good plan to make it. Does anyone have a sample plan?

              Comment


              • #8
                Re: Change Network IP Range

                I would have thought, depending on how much DHCP is used and if clients are in the same building, it could be a couple of days planning and a days (weekend) work

                Something like:
                Reduce length of current DHCP lease to say 1 hour (about 7 days before main change will be done)
                Create but do not activate new scope
                Inventory all devices needing manual change (routers, printers,...)
                Check you have passwords, access permissions, anything else you need to get to them....
                Plan new IPs
                Close of business Friday:
                Activate new scope (deactivate old)
                Scurry around non-DHCP devices changing them (remember this will take down large chunks of your network)
                Change router port forwardings
                Check all DHCP devices have new IPs
                Lots of testing including contacting ALL fixed IP devices
                Tom Jones
                MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
                PhD, MSc, FIAP, MIITT
                IT Trainer / Consultant
                Ossian Ltd
                Scotland

                ** Remember to give credit where credit is due and leave reputation points where appropriate **

                Comment


                • #9
                  Re: Change Network IP Range

                  Originally posted by Engelmar View Post
                  I mean is it possible to finish all this in a week or two? I must make a good plan to make it. Does anyone have a sample plan?
                  With it planned and documented, we would change a 22 subnet with 79 fixed IPs in about 30 minutes if it was prepped properly.
                  1 1 was a racehorse.
                  2 2 was 1 2.
                  1 1 1 1 race 1 day,
                  2 2 1 1 2

                  Comment

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