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  1. #1
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    Windows sever 2012

    i have deployed a windows server on my network (192.168.101.5) connected to one port (ports 19) with vlans 10 -19 tagged on a data switch)

    I have 10 separate devices connected onto 10 individual ports with their own VLAN (10-19) untagged ports. Each VLAN has their own ip interface as well as a ip helper of 192.168.101.5

    in principle devices connected to the switch with VLAN 10-19 should obtain through port 19 (tagged vlans) a DHCP ip address, but the devices are not obtain an ip address.

    To test the DHCP server i connected the server to a separate VLAN 10 untagged port and the device connected to another untagged port, a DHCP ip address is obtained ok.


    i have since changed the sub net of the Windows server to 192.168.70.5 and the only DHCP ip address it will provide is a sub net 70.

    Why wont it alocate ip address from its other scopes ie user on vlan 11 requesting a sub net 11

    Thank you for your help in advance.



    PORT 1/19 - WINDOWS SEVER - TAGGED VLAN 10-19
    PORT 1/10 - PC - UNTAAGGED PORTS VLAN 10 - IP INTERFACE 192.168.10.3 - IP HELPER 192.168.101.5
    PORT 1/11 - PC -UNTAGGED PORTS VLAN 11 - IP INTERFACE 192.168.11.3 - IP HELPER 192.168.101.5
    PORT 1/12 - PC - UNTAGGED PORTS VLAN 12 - IP INTERFACE 192.168.12.3 - IP HELPER 192.168.101.5
    ETC

  2. #2
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    You have different sub-nets so you must have a router to connect them.
    This router must have a helper address set to the IP of the DHCP server - seems to be correct from your description.
    The DHCP server must have sub-nets defined so it can give out addresses in the correct range. Does it?

    Are you sure the DHCP requests are being sent to the server? Use Wireshark to view DHCP requests.
    Have you set the IP mask correctly on the server? It should be 255.255.255.0.
    Is the default gateway correct?

    cheers, Paul

  3. #3
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    windows 2012

    Quote Originally Posted by Paul T View Post
    You have different sub-nets so you must have a router to connect them.
    This router must have a helper address set to the IP of the DHCP server - seems to be correct from your description.
    The DHCP server must have sub-nets defined so it can give out addresses in the correct range. Does it?

    Are you sure the DHCP requests are being sent to the server? Use Wireshark to view DHCP requests.
    Have you set the IP mask correctly on the server? It should be 255.255.255.0.
    Is the default gateway correct?

    cheers, Paul
    Thank you for the reply.

    Within the network setup the windows sever is connected to a data switch 192.168.101.3 ( this is the gateway of on the windows server)
    The layer 3 switch on the network has various ports programmed with separate VLANs-sub nets with a DHCP helper of 192.168.101.

    I have simply plugged a pc into the layer3 switch, port 2 which is associated to VLAN 11, wireshark running and can see the DHCP requests, but no reply.

    If I plug a pc into port 3 with VLAN 101 (the same as the windows sever) I receive a DHCP request and acknowledgement.

    I then modified the windows severs ip address to 192.168.70.5 and modified everything else to suite and succeeded in getting a DHCP request and acknowledgement only form the same VLAN subnet as the windows sever.

    Any other VLAN does not receive an acknowledgement. I then tried to place the windows sever into a tagged port along with a whole load of other vlans and again only a pc connected to the same vlan as the server would receive a reply !!

    I have tried a second data switch and the symptoms are exactly the same..... any ideas ??




    The layer 3 switch has various vlans programmed also with a dhcp helper of 192.168.101.5

    I have a numerous scopes on the windows sever each with their own credenitials/policies ie 192.168.10.1 -100 subnet 255.255.255.0 gateway 192.168.10.3 (each vlan having their own ip interface on the switch as a gateway).

  4. #4
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    Is the server on VLAN0? It needs to be on a VLAN that will accept traffic from any VLAN - not a trunk.

    cheers, Paul

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