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Multi Site IP Scheme

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  • Multi Site IP Scheme

    I am in the process of splitting my network and was hoping for a little more advice.

    I am looking to run my servers from a datacenter (with a small amount of servers at an office location). My users will still be in the Office location.

    I have to build the system while it is in production so I have to build everything local and then move the hosted solution out.
    Cisco 5510 Router
    Cisco 2960 (24 Port Switch)
    2 VMWare servers (ESXi4.1) on Vsphere Essentials Plus
    1 EMC NX4

    Cisco ASA 5505 Router
    DLink 10/100/1000 switch
    1 VMWare server (ESXi4.1)
    1 EMC NX4
    Printers / Desktops / etc. etc.
    Original network: 10.10.111.x (subnet

    After some advice here I think the best route is to run Sites and services and place a DC (or two) in both locations and then route via a Site to Site VPN to have everything under 1 domain.

    My question:
    Does it make sense to increase my subnet and build both networks locally and once I move the networks I would then create the routes and lower the subnet back down?

    -- Example --
    Network Prep:
    1) Change subnet to
    2) All "office" machines to use 10.10.222.x
    3) All "Hosted" machines to use 10.10.111.x

    1) Move hosted machines offsite
    2) create VPN site to site tunnel between sites
    3) change subnets back to via DHCP or static

    My thought is that this will allow the EMC devices to replicate and I would not have to change any IPs for storage arrays, databases, websites, VMs, etc.

    My obvious concern is to limit the chatter between the sites, but we run a small network and I'm not sure of the impact of the subnet over the WAN.

    Thanks for your help!

  • #2
    Re: Multi Site IP Scheme

    If you're gonna build it in one place, but then move part of it, build it as 2 separate subnets even though it's in the same building to start with. That way you'll test the site-to-site link services before you put a real 3rd-party comms link in the middle. Your build will include routing and all the rest, while everything is local to you for troubleshooting, etc.

    If both sites are on the same subnet once it's deployed, you'll get ARP broadcast traffic through the link in addition to anything else. The 2-DC idea, or at least routing between subnets if there's only 1 DC servicing everything from just one site, will eliminate the broadcasts through the WAN link.
    MSCA (2003/XP), Security+, CCNA

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    • #3
      Re: Multi Site IP Scheme

      Microsoft recommends creating a subnet for each site even if your AD doesn't span more than one subnet\site. My advice (much like RicklesP) is to configure ADS&S the way it will be in it's final iteration. I differ from RicklesP in that I would leave the DC's in their current subnet\site until you actually move them physically. When you do move them, then move them into the appropriate subnet\site in ADS&S. AD will make the needed changes to the topology automatically.