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Frequent Contributor II

Occasional client just will not get a DHCP address...

On occasion I get a call from our helpdesk about a student laptop that will not connect our wireless. It will connect to the signal and I'll see it in the controller but it will not get an IP address. Currently I have a student with this very problem and he was kind enough to leave it at the helpdesk so we could troubleshoot it today. No matter what I do I cannot seem to get his laptop to get an address. And he tells me it works just fine everywhere else but here. (I hate it when they say that LOL)

 

Here is a look at its connection:

connection issue 1.PNG

 

and

 

connection issue 2.PNG

 

On the client side of things we have tried:

- disabling IPv6 (shouldn't matter but worth a shot)

- updating WLAN NIC drivers

- Deleting WLAN NIC out for device manager and reinstalling

- flushing cache

- ever popular disable/re-enable of WLAN NIC

- various CLI ipconfig /release & renew commands

- rebooting (of course)

 

On the controller side of things I have:

- checked the blacklists as this is blacklist type behavior, blacklist continually clear

- checked on signal strength to the client

- checked interference levels on the AP the client is trying to connect to

- Checked and double checked the DHCP server, always plenty of open leases for new clients

- issued a #clear IP DHCP binding on the controller in question just to make sure there were no DHCP lease issues

 

Not sure where to go from here gang, any ideas?

Scott McNeil - Sr. Network & Security Engineer, Global Process Automation
Network+ | CWNA | CWTS | ACSP | ACMP | ACMA | BREC
26 REPLIES

Re: Occasional client just will not get a DHCP address...

 

Can you please share the user-role ?

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Frequent Contributor II

Re: Occasional client just will not get a DHCP address...

being that the user doesn't get an Ip, they never progress farther thant the initial pre-authentication role for the guest network:

 

guest role.PNG

Scott McNeil - Sr. Network & Security Engineer, Global Process Automation
Network+ | CWNA | CWTS | ACSP | ACMP | ACMA | BREC

Re: Occasional client just will not get a DHCP address...

Can you add the logon-control to the ACL list right at the top under that user-role

 

And also do the same to the guest-role

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Frequent Contributor II

Re: Occasional client just will not get a DHCP address...

Here is the cp-initial list:

 

cp-initial.PNG

 

Then is the captive portal acl:

 

captive.PNG

 

And then the guest vpn allowance ACL:

 

vpn.PNG

Scott McNeil - Sr. Network & Security Engineer, Global Process Automation
Network+ | CWNA | CWTS | ACSP | ACMP | ACMA | BREC
Guru Elite

Re: Occasional client just will not get a DHCP address...

americanmcneil,

 

What is the ACL after the user authenticates?

 

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Frequent Contributor II

Re: Occasional client just will not get a DHCP address...

The standard Guest roll on the controller, but the user doesn't make that far. I can still post if you like though

Scott McNeil - Sr. Network & Security Engineer, Global Process Automation
Network+ | CWNA | CWTS | ACSP | ACMP | ACMA | BREC
Guru Elite

Re: Occasional client just will not get a DHCP address...

americanmcneil,

 

Please take a look at the troubleshooting cheatsheet here:  http://community.arubanetworks.com/aruba/attachments/aruba/84/106/1/Troubleshooting+Cheat+Sheet-.pdf to see how to turn on DHCP debugging...

 

 

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Frequent Contributor II

Re: Occasional client just will not get a DHCP address...

OK, got that set. The student came by and got his laptop from the help desk. I am hoping he brings it back on Monday so I can continue to work on this. Any other suggestions for the meantime?

Scott McNeil - Sr. Network & Security Engineer, Global Process Automation
Network+ | CWNA | CWTS | ACSP | ACMP | ACMA | BREC
MVP

Re: Occasional client just will not get a DHCP address...

For any IP address acquisition issues, always issue the following on the controller:

 

configure terminal
logging level debugging network subcat dhcp
end

 Then, issue:

 

show log network 100 | include <clients_mac_address>

 This will tell you if the controller is getting the client's DHCPDISCOVER messages, as well as whether it is observing DHCPOFFERS from the server. Assessing the controller's observations of DHCP transactions will point you in the direction for troubleshooting. For instance:

  • if DISCOVERs are seen but no OFFERs, go to the DHCP server to see if the DISCOVERs ever arrive
  • If the DISCOVERs and OFFERs are seen on the controller, go to the client and do a packet capture to see if the OFFERs ever make it to the client.

Hope this helps a bit.

 

And don't forget to disable DHCP debugging when you're done:

configure terminal
no logging level debug network subcat dhcp
end

 

 

==========
Ryan Holland, ACDX #1 ACMX #1
The Ohio State University
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