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Aruba Wireless Client DHCP Timeout Issue

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  • 1.  Aruba Wireless Client DHCP Timeout Issue

    Posted May 21, 2024 09:46 AM

    Recently upgraded all my IAP 205's from AirWave to 515s in Central. On the latest 8.12.0.0 firmware. I have numerous sites in Central with 515s that work fine, but this one particular site is having an excessive amount of Client DHCP Timeouts. Ive tried everything from adding and removing the ip helper-address command on the switch SVI, making sure that central was not using named VLANs, adjusting the radio power for 2.4 from 9-12 to 6-9 and 5 from 12-15 to 9-12 just incase it was a roaming issue. nothing is working. is there any thing else to try?



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    Mr. MKP
    Network Administrator
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  • 2.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted May 21, 2024 12:19 PM
    Edited by chulcher May 21, 2024 12:19 PM

    Are the clients actually getting an IP address eventually?  Is there anything to characterize the clients that are struggling?

    FYI, usual guidance is for the 5 GHz to have a minimum power that is 3-6 dBm higher than the maximum 2.4 GHz power.



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    Carson Hulcher, ACEX#110
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  • 3.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted May 21, 2024 12:34 PM

    Yes they will eventually get a DHCP address. sometimes it can take 5 minutes, or multiple reconnect attempts before they get one. No one on the wired side is having this issue and it only began after I upgraded to the 515s. I usually do ipconfig renews a couple time in command prompt to get my IP address to finally show up. In Central I see many of DHCP Timeouts in the event log. We know its not the DHCP server as I mentioned LAN connections are not having this issue and it only began after upgrading from 205's in AirWave to 515s in Central.



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    Mr. MKP
    Network Administrator
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  • 4.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted May 21, 2024 01:11 PM

    I'd be looking at possible configuration differences between that site and others to see if something has accidentally been configured differently.  Another option is to run various packet captures to see where the DHCP packet gets to and hopefully where the delay is occurring.



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    Carson Hulcher, ACEX#110
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  • 5.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted May 21, 2024 01:26 PM
    Edited by MKP20 May 21, 2024 01:26 PM

    the configuration has been checked and compared to other sites. all the sites i have get their configuration from the group they belong to as we use the same SSID's at all our locations. What we have discovered int he pcap files is the pc sends out the dhcp request and nothing comes back to the pc. the dhcp logs show it receives the request and send the acknowledgement back but somewhere along the line the acknowledgement doesnt make it back to the pc. with multiple attempts it will finally get back. One theory is that the access points being close to one another is causing clients to roam before they receive the ack from the dhcp server. the 205s didnt do this and the 515s were a one for one replacement.



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    Mr. MKP
    Network Administrator
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  • 6.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted May 22, 2024 11:17 AM

    Might want to open a case with TAC for further troubleshooting.



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    Carson Hulcher, ACEX#110
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  • 7.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted 25 days ago

    Running AOS10 but having this exact issue at a customer. Aruba ERT got tunnel vision on it beeing too few APs. So I was wondering if you have made any advances here.

    we are running cloudauth also.




  • 8.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted 24 days ago

    Hi @manr_Agnitio

    You can try to play with Local Probe Request Threshold. If you have it on manual, try to go to Automatic.



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    Gorazd Kikelj
    MVP Guru 2024
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  • 9.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted 24 days ago

    Did you check AI Insight on probable causes of this behavior? 

    Best, Gorazd



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    Gorazd Kikelj
    MVP Guru 2024
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  • 10.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted 24 days ago

    After talking to TAC and doing a remote troubleshooting session, we could not resolve the issue. so i got curious and looked at things from the switch level. i noticed that the AP native vlan and another vlan specified for my public WLAN were having the issue even if i created a access LAN port on the switch. Im currently waiting on Cisco to contact me so they can view the pcap and possibly tell me what the issue is.



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    Mr. MKP
    Network Administrator
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  • 11.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted 24 days ago

    UPDATE... talked with Cisco Support and found out the issue was not related to the two WLAN VLANs but the data VLAN. it was causing a lot of icmp drops due to Cisco's new Control Plane Protections feature in the 9000 series switches. Tech support ran the following commands
    monitor capture cap control-plane in match any buf size 100 start
    monitor capture cap stop
    show mon cap cap buf br

    after only 7 seconds of running the first command we had 4700 drops and the last command showed those drops which all had IP addresses from our data vlan. we put the below commands on the data vlan and all the drops stopped.
    no ip redirects

    things are looking better now with dhcp request. Hopefully this will help others out who are having this issue and are using Cisco switches.



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    Mr. MKP
    Network Administrator
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  • 12.  RE: Aruba Wireless Client DHCP Timeout Issue

    Posted 23 days ago

    Hi @MKP20

    Many thx for sharing this solution. It will come handy.

    Best, Gorazd



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    Gorazd Kikelj
    MVP Guru 2024
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