DHCP+SUPERSCOPE+VLAN=NACK

Discussion in 'Windows Networking' started by jimmy.newell, Feb 16, 2006.

  1. jimmy.newell

    jimmy.newell Guest

    Setup-Windows 2003 Standard Edition Domain Controller holding FSMO
    roles running DHCP, DNS, and WINS.

    The Microsoft propaganda that I've come across suggests that DHCP
    Superscopes are best utilized when you have several logical networks
    running across the same physical segment.

    I.e. if you have 5 VLans running on one wire- it becomes appropriate to
    utilize superscopes.
    So here is the problem I'm having. The layer 3 router which routes
    between the VLans is appropriately setup. We are utilizing the DHCP
    helper command in the router to forward all DHCP requests to our
    server. This seems to work fine *most* of the time. Spontaneously a
    few systems seem to get stuck in this rut of being unable to contact
    the DHCP server. The DHCP server shows a NACK in the log file. The
    resolution has been to delete the lease on the DHCP server and change
    the VLAN of the port that the system is connected to. This has been
    the only way to solve this problem.

    Alternatively we removed the affected scope from the superscope and the
    problem goes away. Why are we having this problem if the scope is
    contained in the Superscope? Why would the DHCP server be sending a
    NACK on the VLAN? Isn't this the point of a superscope? Is it
    necessary to use the Superscopes? What's the freaking point of a
    superscope? Why if we have 7 subnets /VLans only one or two are
    affected? Why if we have 400 pcs only 20-30 affected? Why doesn't
    Microsoft have better logging capabilities on DHCP Server? Why won't
    Bill Gates loan me $100,000?
     
    jimmy.newell, Feb 16, 2006
    #1
    1. Advertisements

  2. There are not talking about VLANs, they are talking about Multi-Netting.
    VLANs are on different "logical wires" which behaves the same way as
    different "physical wires" as far as DHCP is concerned.

    Multi-Netting is when you run more than one IP Segment on the same physical
    wire *without* doing VLANs. It is rarely done anymore,...in fact,..in my
    opinion,..the invention of VLANs eliminated the need for Multi-Netting for
    the most part.

    Get rid of the SuperScopes. Use separate individual regular Scopes.

    --
    Phillip Windell [MCP, MVP, CCNA]
    www.wandtv.com
    -----------------------------------------------------
    Understanding the ISA 2004 Access Rule Processing
    http://www.isaserver.org/articles/ISA2004_AccessRules.html

    Microsoft Internet Security & Acceleration Server: Guidance
    http://www.microsoft.com/isaserver/techinfo/Guidance/2004.asp
    http://www.microsoft.com/isaserver/techinfo/Guidance/2000.asp

    Microsoft Internet Security & Acceleration Server: Partners
    http://www.microsoft.com/isaserver/partners/default.asp

    Deployment Guidelines for ISA Server 2004 Enterprise Edition
    http://www.microsoft.com/technet/prodtechnol/isa/2004/deploy/dgisaserver.mspx
    -----------------------------------------------------
     
    Phillip Windell, Feb 16, 2006
    #2
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.