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DHCP option for APs with a controller cluster

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  • 1.  DHCP option for APs with a controller cluster

    Posted Feb 27, 2023 07:20 PM

    Hi there,

    I set up a controller cluster at one campus site with an exernal DHCP server.

    To be save I'd like to set the DHCP settings of the server to hand out both IP adresses of the clustered controllers. Just in case one of the two fails...

    For now the setting is:

    option masterip <IP of controller 1 in cluster>;

    What is the right way to add the IP adress of the second controller to the config?

    Can I just add the IP with a "," or is there another option like backupip or standbyap or just another masterip?

    Thanks for the help.

    All the best

    Max



  • 2.  RE: DHCP option for APs with a controller cluster

    MVP GURU
    Posted Feb 28, 2023 08:57 AM

    If it is a cluster of Controllers you would want to configure VRRP. This will give you a Virtual IP (VIP) to point the APs to. The AP just has to contact one of the controllers, and then the controller will send down the LMS and B-LMS in the AP system profile. If you have one cluster, just configure the LMS. Each AP will get a node list for each controller in the cluster, so there is no need to send a B-LMS. If you have another cluster, you can set that VIP as the B-LMS.



    ------------------------------
    Dustin Burns

    Lead Mobility Engineer @Worldcom Exchange, Inc.

    ACCX 1271| ACMX 509| ACSP | ACDA | MVP Guru 2022-2023
    If my post was useful accept solution and/or give kudos
    ------------------------------



  • 3.  RE: DHCP option for APs with a controller cluster

    Posted Feb 28, 2023 11:19 AM

    Hi Dustin,

    Thank you for the quick reply. I tried giving VRRP IPs but there is only one IP available for each controller. Setting up a virtual router table could be a solution but I read about issues if one of the controllers is down than the VRRP might not be working any more. Also the RADIUS server is set up to only accept the IP adresses of the controllers (not the VRRP IPs) for requests.

    There are not gonna be more than 2 Controllers in a cluster per each campus site so I would just like to hand over both IPs in the DHCP response for all unprovisioned APs.

    Perhaps you can tell me where to get the documentation for the DHCP config?

    Thanks




  • 4.  RE: DHCP option for APs with a controller cluster

    MVP GURU
    Posted Feb 28, 2023 11:51 AM

    VRRP will still allow the controllers to retain their own addresses. Only one of them at a time will respond to requests destined for the VIP (a shared IP address between the two) For example:

    Controller VIP: 10.10.10.1

    Controller 1 (VRRP Active): 10.10.10.2

    Controller 2 (VRRP Standby): 10.10.10.3

    DHCP response to AP to reach controller: 10.10.10.1 (which will send controller destination traffic to Controller1 because it is the active. If the active goes down, the standby Controller 2 will accept the 10.10.10.1 traffic)

    Like I mentioned, once you have the AP provisioned, the DHCP option will no longer be needed unless the AP loses its configuration. It will get its controller termination settings from the provisioning controller.



    ------------------------------
    Dustin Burns

    Lead Mobility Engineer @Worldcom Exchange, Inc.

    ACCX 1271| ACMX 509| ACSP | ACDA | MVP Guru 2022-2023
    If my post was useful accept solution and/or give kudos
    ------------------------------



  • 5.  RE: DHCP option for APs with a controller cluster

    EMPLOYEE
    Posted 26 days ago

    You can also return a DNS name in your DHCP, and put multiple IP addresses to that DNS name (round-robin). If the first IP returned does not respond, the AP should connect to the other.



    ------------------------------
    Herman Robers
    ------------------------
    If you have urgent issues, always contact your Aruba partner, distributor, or Aruba TAC Support. Check https://www.arubanetworks.com/support-services/contact-support/ for how to contact Aruba TAC. Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba Networks.

    In case your problem is solved, please invest the time to post a follow-up with the information on how you solved it. Others can benefit from that.
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