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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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Wireless Clients/DHCP issues/AP 315

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  • 1.  Wireless Clients/DHCP issues/AP 315

    Posted Sep 15, 2022 03:54 PM
    Hello,

    Having issues with wireless clients windows/MAC and getting DHCP - DHCP ip-helper on core switches pointing to CentOS Linux DHCP server

    We can see the Discover/Offer but no Request/Acknowledgement - This is from a specific 315 series

    Is it possible to much client load on one DHCP server - 11k clients


  • 2.  RE: Wireless Clients/DHCP issues/AP 315

    EMPLOYEE
    Posted Sep 16, 2022 09:07 AM
    Does not look good to me. What do you see if you run a packet capture (like Wireshark) on the client? Do you see the DHCP Offer there? And if so do you see a DHCPREQUEST then? Is the client able/allowed to reach the DHCP relay (that is probably the IP on the core where you configured the ip-helper) and server for its DHCP request and renews?

    ------------------------------
    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.
    ------------------------------

    Original Message


  • 3.  RE: Wireless Clients/DHCP issues/AP 315

    Posted Sep 16, 2022 09:25 AM
    Hi Herman,

    Thinking the same thing not looking good on the DHCP side - It's hard to get a hold of the client machines experiencing the issue to run pcaps on them. Is there anything that can be run on the mobility master or wireless controllers that could see the DHCP request and where that's getting lost or if the offer is reaching the client? We have 11k clients and only 3 or 4 have experienced the issue this week where they don't get a DHCP Request back but you can see the Discover/Offer messages from our linux dhcp server. So majority of our clients are fine which means the ones having issues should be able to reach the DHCP server as well. I'm just wondering if something is getting goofy on our linux dhcp server with 11k clients trying to get an address from that one DHCP server/IP helper-address on the core.

    I will have to try doing some pcaps to see the result at the clients

    Thank you,
    Eric Berg
    Original Message


  • 4.  RE: Wireless Clients/DHCP issues/AP 315

    EMPLOYEE
    Posted Sep 16, 2022 10:47 AM
    You can run packet (datapath) captures from the controller as well, but I would start from the client. If the packet is not sent there, you'll have to search in the client, if it is sent but not arriving on the DHCP server, you will need to go step by step to find out where the packet is lost.

    Does the role that the client is assigned to block anything? Any ACLs/Firewalls in between the client and the DHCP server?

    ------------------------------
    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.
    ------------------------------

    Original Message


  • 5.  RE: Wireless Clients/DHCP issues/AP 315

    Posted Sep 16, 2022 11:55 AM
    The role the client is assigned to shouldn't block anything that would cause the issues we're seeing (in theory) has 7k other clients utilize the same role and can connect. this week it's just been 3 clients a MacBook-Pro and 2 android devices. 

    From the lease logs on the linux server the only thing that sticks out is the UID being different from working clients.
    lease 172.17.75.118 {
    starts 5 2022/09/16 14:08:50;
    ends 5 2022/09/16 14:10:50;
    cltt 5 2022/09/16 14:08:50;
    binding state free;
    hardware ethernet 3c:06:30:25:1b:3c;
    uid "\001<\0060%\033<";
    client-hostname "MacBook-Pro-2";

    I can't figure out how to clear a single dhcp lease in linux for the life of me coming from a windows server background. 

    I found this thread https://community.arubanetworks.com/browse/articles/blogviewer?blogkey=504044b0-f16b-4688-bfa9-9a3a24331298 which goes over promiscuous option and changing that value to one. However the difference is they're running a VMC where we run physical 7240xm's but our DHCP server is in VMWare without that enabled be curious if that's why we see so many dhcp messages from multiple sources.

    Then I'm assuming there is no way to see if those dhcp messages are being sent through the AP between client/controller because you can't ssh into them so I would have to console into an AP to see if there are any logs there correct?

    Thank you,
    Eric Berg
    Original Message


  • 6.  RE: Wireless Clients/DHCP issues/AP 315

    Posted Sep 16, 2022 03:44 PM
    Interesting that the client has an IP in the ARP table on the core but nothing shows in mobility master for an IP address but the client is in a connected/active session to an AP. Thoughts?
    Original Message


  • 7.  RE: Wireless Clients/DHCP issues/AP 315

    EMPLOYEE
    Posted Sep 21, 2022 07:34 AM
    May be best to work with Aruba support to do some interactive troubleshooting. With the information available now, it's just guessing, and as you mention it's only from specific APs of the AP-315 type, if all APs share the same configuration, and traffic is tunneled to a controller, it may be a very specific issue.

    ------------------------------
    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.
    ------------------------------

    Original Message


  • 8.  RE: Wireless Clients/DHCP issues/AP 315

    Posted Sep 21, 2022 07:53 AM
    Hi Herman,

    I'm going to open a case this morning has it's just one client who doesn't get an IP address it's just blank and it's a macbook so not sure why I'm not getting the dhcp request from the client after we see the discover and offer. All other clients are good currently. This doesn't explain the amount of dhcp requests as the leases are set for 30 minutes so not sure why that happens every 2-3 minutes but maybe clients roaming they send a dhcp request.

    Anyways opening a tac case see what's going on and update you.

    Thank you for the help with this
    Original Message


  • 9.  RE: Wireless Clients/DHCP issues/AP 315

    EMPLOYEE
    Posted Sep 21, 2022 10:17 AM
    Some Operating Systems indeed to a DHCP after each roam to 'support' mistakes in VLAN between one AP and the other. Of course all your sessions will be disconnected if the IP address changes, so make sure that a client will always get the same VLAN.

    This probably is separate from what you see with the macbooks not getting an IP.

    ------------------------------
    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.
    ------------------------------

    Original Message


  • 10.  RE: Wireless Clients/DHCP issues/AP 315

    Posted Sep 21, 2022 01:00 PM
    I was able to work with tac who ultimately didn't figure it out but put me in the right direction with the user-table commands

    I was able to look at the user-table by mac and see that it wasn't returning an IP for the client. So then I show the user-table by ip and sure enough a different mac address had the IP. So I blacklisted that client and have to figure out how they took that IP as they were in a denyall role.

    Original Message