Re: dhcp sizing

From: Phillip Windell (_at_.)
Date: 01/06/05

  • Next message: Jennifer Sanders: "Re: Remote Desktop and Win2k3 SBS" 
    Date: Thu, 6 Jan 2005 15:12:20 -0600

    "Al Mulnick" <amulnick_No_SPAM@ncDOTrr.com> wrote in message
    news:%23vU4mPB9EHA.3944@TK2MSFTNGP12.phx.gbl...

    > defined, represents a different subnet. I work at a company with > 1400
    > locations at the moment, each with it's own network.
    > ...........
    > The routers are only capable of three entries for bootp forwarders.
    That's > what's driving the whole change in the first place. If it could
    handle

    Those two comments spell disaster to me. I would never want to totally
    centralize something like that. Do you know what mess that will create if
    those 1400 locations lost contact with the Central location and cannot
    receive from the DHCP?

    > four, it would not be an issue in the least. To simplify the service
    > provided, I'd like to move this down to two servers in total for the
    remote
    > networks only. All centralized networks will be on the other two servers.
    > The easiest way to do this is to put all scopes on all servers and flip
    the
    > routers as conditions allow.

    Well two servers down from four cure the router config limitation, but it
    doesn't solve the disaster created by centralizing that many site's DHCP to
    become dependent upon one site for their existance. You seriously need to
    think about a "distributed model",...just the opposite of what you are
    doing.

    > What makes you say no superscopes? What's your experience with them that
    > makes you say that?

    I've yet to find a "real live" situation where they even need to exist in
    the first place. If you do a search for material about them you will find
    most of it vague and hard to follow the logic and the two things that you
    will read about them if you do a search are:

    1. They take multiple Scopes and make them behave as one. This is opposite
    of what you want to do, and it doesn't even make sense to me,...why would
    someone take different scopes and make them act as one if they weren't in
    the same subnet,...and if they are in the same subnet then what's the point
    of multiple scopes in the first place when you can create one scope to
    handle it.

    2. They are used when multiple subnet share the same physical "wire", but
    *not* a VLAN situation. To me, that is just a bad topology and not a
    legitament way to build a network in the first place,...but then, I don't
    get to run the world.

    Some of MS's Documentation lists these purposes:

    1. DHCP clients are located on a single physical network segment that
    includes multiple logical IP subnets.

    2. Multiple DHCP servers manage separate logical subnets on the same
    physical subnet.

    3. The available address pool for an active scope is nearly depleted and
    more computers must be added to the physical network segment.

    4. Clients are migrating to a new scope.

    5. You need to support DHCP clients on a network that has multiple logical
    subnets in one physical subnet on the other side of a BOOTP/DHCP relay
    agent.

    #1, #2, and #5 are needless since you should not even design a topology that
    way to begin with, and if you find yourself with one it should be
    redesigned.

    #3 is useful but could easily been avoided by using the full IP Range in the
    scope to begin with and use Excusions to cut back the distributed addresses.
    The Exculsions can later be adjusted easily to accomidate more machines.
    But if you do "Supernetting" then that could be a legitament use of it.

    I can somewhat see the point of #4, but it would only be a temporary thing
    used as a "migration" techinque.

    The link for those items is:
    http://www.microsoft.com/resources/documentation/WindowsServ/2003/all/deployguide/en-us/Default.asp?url=/resources/documentation/windowsserv/2003/all/deployguide/en-us/dnsbc_dhc_mrqk.asp 

    -- 
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com
-- 
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com
  • Next message: Jennifer Sanders: "Re: Remote Desktop and Win2k3 SBS"

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