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Access network design for branch, remote, outdoor, and campus locations with HPE Aruba Networking access points and mobility controllers.
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Source nat inside, with external DHCP via DHCP Helper Address?

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  • 1.  Source nat inside, with external DHCP via DHCP Helper Address?

    Posted Dec 01, 2017 11:09 AM

    We've got a few controller-only VLANs set up running source nat inside and local DHCP scopes on the controller, but I'm doing some testing to see about using our existing external DHCP server for these VLANs.  So far I'm not having much luck.  Here's the setup:

     

    Role: vending, VLAN51

    any any dhcp permit

    block internal networks (10.x)

    allowall

     

    VLAN/IP: 51

    IP: 192.168.3.1/24

    source nat inside

    DHCP Helper Address: 10.64.10.23 (the controller can reach this)

    This VLAN isn't associated with any physical port or port channel.

     

    Will this not work, or am I just missing something dumb?



  • 2.  RE: Source nat inside, with external DHCP via DHCP Helper Address?
    Best Answer

    EMPLOYEE
    Posted Dec 01, 2017 11:29 AM

    Unfoortunately, it will not work across a source-nat boundary.

     

    There has been alot of back and forth on this in the distant past, and since ArubaOS 6.2 the controller source ip in the DHCP packet has always been the controller uplink IP instead of the unroutable default gateway of natted clients.  This is the reason why it wold not work with natted clients on the controller.



  • 3.  RE: Source nat inside, with external DHCP via DHCP Helper Address?

    Posted Dec 01, 2017 11:32 AM

    Thanks Colin!