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XP clients won´t get IP from new Windows DHCP Server (old one is Linux)

    Question

  • I have 1 Linux DHCP server over my network and plan on migrating DHCP service to a Windows Server 2003.

    Clients are Windows XP on 10.0.0.0/24 network
    Linux DHCP is 10.0.0.2 - scope 10.0.0.20-200
    Windows DHCP is 10.0.1.2 - scope 10.0.0.20-200
    Router has IPs 10.0.0.1 and 10.0.1.1
    Router is forwarding DHCP packets between subnets.

    If I stop Linux DHCP service, clients won´t get a new IP from Windows DHCP.
    Instead, they get a limited or null conectivity.
    Running wireshark on Windows DHCP i can see the DHCP Discover packets reaching (what means no router forwarding problem) but no DHCP Offer is sent.
    The clients are sending DHCP Discover with option 50 - requested IP Address - with the old IP address issued by Linux DHCP.
    Probably Windows DHCP does not recognize it and thinks there is another DHCP server on the network and does not respond to the request.
    Since the client receives no response, it changes to APIPA address.
    Windows DHCP should NACK the request so that the client would send a new DHCP Discover without option 50, witch should then get a valid IP from Windows DHCP.

    A few clients can get leases from Windows DHCP, can´t figure out why.
    The other ones i can ipconfig /release and ipconfig /renew and they will get IP from Linux DHCP, even though I have configured the option "min-secs" at Linux, so that the server will wait 2 seconds before offering a lease.

    If i stop the DHCP server, most clients loose conectivity.
    In this case ipconfig /release and ipconfig /renew won´t help, because Windows DHCP won´t respond the DHCP Discover.

    I know that Linux DHCP has the option "authoritative" so that it responds to every requests it gets, but i can´t find anything like that on Windows Server.
    P.S.: Windows DHCP server and scope are "Authorized" in Active Directory.

    Help!
    Thursday, March 11, 2010 12:32 AM

All replies

  • Hello,

    try it with a DHCP relay agent in the other subnets to make sure it works and exclude the router as a problem.

    Best regards Meinolf Weber Disclaimer: This posting is provided "AS IS" with no warranties, and confers no rights.
    Thursday, March 11, 2010 6:26 AM
  • Damn.
    I have no Windows Server on the same client subnet to put a DHCP relay agent.

    Anyway, if i can capture the packets with wireshark running over the Windows DHCP, doesn´t it exclude th problem being the router or the lack of a realy agent?

    The DHCP Discover gets to the Windows Server but no DHCP Offer is issued (in most cases, because as I said, some machines on the same client subnet are getting their IPs from the Windows DHCP, don´t know why).
    Thursday, March 11, 2010 11:36 AM
  • Hello,

    i have seen that if the router isn't complete capable of DHCP forwarding that the offer doesn't reach the client.
    Best regards Meinolf Weber Disclaimer: This posting is provided "AS IS" with no warranties, and confers no rights.
    Friday, March 12, 2010 9:35 AM
  • OK, but i´m capturing packets at the Windows DHCP Server, at the other side of the router.
    The DHCP Discover from the clients are hitting the server, so, there is no problem with the router until now.
    Next step, the server should send a DHCP Offer back to the clients.
    Again, there could be a problem with the router not forwarding those packets, but the problem occurs before that.

    I´m capturing packets at the server, and it doesn´t send DHCP Offer.

    Resuming:
    DHCP Discover from clients hit the Server (no problem with router).
    Server doesn´t respond back with DHCP Offer.
    If the server responded with DHCP Offer and it did not reach the clients, then i would think of a problem with the router.
    Friday, March 12, 2010 4:53 PM
  • I think you need to try add scope 10.0.0.20-200 on windows DHCP server in a superscope.
    Tuesday, August 10, 2010 2:43 PM
  • I have 1 Linux DHCP server over my network and plan on migrating DHCP service to a Windows Server 2003.

    Clients are Windows XP on 10.0.0.0/24 network
    Linux DHCP is 10.0.0.2 - scope 10.0.0.20-200
    Windows DHCP is 10.0.1.2 - scope 10.0.0.20-200
    Router has IPs 10.0.0.1 and 10.0.1.1
    Router is forwarding DHCP packets between subnets.

    If I stop Linux DHCP service, clients won´t get a new IP from Windows DHCP.
    Instead, they get a limited or null conectivity.
    Running wireshark on Windows DHCP i can see the DHCP Discover packets reaching (what means no router forwarding problem) but no DHCP Offer is sent.
    The clients are sending DHCP Discover with option 50 - requested IP Address - with the old IP address issued by Linux DHCP.
    Probably Windows DHCP does not recognize it and thinks there is another DHCP server on the network and does not respond to the request.
    Since the client receives no response, it changes to APIPA address.
    Windows DHCP should NACK the request so that the client would send a new DHCP Discover without option 50, witch should then get a valid IP from Windows DHCP.

    A few clients can get leases from Windows DHCP, can´t figure out why.
    The other ones i can ipconfig /release and ipconfig /renew and they will get IP from Linux DHCP, even though I have configured the option "min-secs" at Linux, so that the server will wait 2 seconds before offering a lease.

    If i stop the DHCP server, most clients loose conectivity.
    In this case ipconfig /release and ipconfig /renew won´t help, because Windows DHCP won´t respond the DHCP Discover.

    I know that Linux DHCP has the option "authoritative" so that it responds to every requests it gets, but i can´t find anything like that on Windows Server.
    P.S.: Windows DHCP server and scope are "Authorized" in Active Directory.

    Help!

    What I see is the DHCP Scope on the Windows Server is different than the Linux machine. No matter what the OS type, DHCP will only provide scope offerings on a configured NIC of the same IP range or DHCP Relay Agent, or what is called in the Unix/Linux arena, IP Helper. If the IPs in the scope do not match either the configured NIC or Helper/Agent, it will not work.
    Ace Fekay, MVP, MCT, MCITP EA, MCTS Windows 2008 & Exchange 2007, MCSE & MCSA 2003/2000, MCSA Messaging 2003, Microsoft Certified Trainer, Microsoft MVP - Directory Services. This posting is provided AS-IS with no warranties or guarantees and confers no rights.
    Thursday, August 12, 2010 5:12 AM