Wireless Access

Hi all, hoping for some help/insight here. I have a customer with clients connecting through two local controllers. intermittently, devices are not obtaining IP addresses on a particular VLAN. I've narrowed it down using packet captures and it look slike the issue is on the controller. The PCAP shows the packets are being sent to the controller.

I've enabled DHCP debugging and its missing either the DHCPOFFER or DHCPACK packets when the failure occurs.

I need to know whether the controller could be dropping the packets and not reporting this in the output.

(aruba.customer.uk) #show log network all | include <clientMac>

Dec 9 22:43:13 :202534: <DBUG> |dhcpdwrap| |dhcp| Datapath vlanXXX: DISCOVER <clientMac> Transaction ID:0x44630f63 Options 3d:01f025b7d1f3a1 39:05dc 3c:6468637063642d352e352e36 0c:616e64726f69642d39616463663432393866643939646538 37:012103060f1c333a3b

The setup is running 6.4.x

Hello,

Wow..!! thats great but have you checked the Controller to DHCP server link.

Are you sure whether the DHCP is really sending those packets to the Controller.

Between, I assume, we have enough IP resources in the DHCP server.

#show interface vlan <VLAN Id> --> please check User VLANs whether the BCMC optimization is enabled, if it is then disable

#show wlan virtual-ap <VAP Profile Name> --> Check whether the "broadcast-filter" knob is enabled, if it is then disable

Below are test cases to try:

• You can try configuring a Test VLAN with Test DHCP pool on the controller and assign the test VLAN to the particular SSID
• Is there any compalin from the Wired users who are from the same VLAN or try to connect a Wired device to the Switch and to the Controllers port, see if the issue is replicating

By these steps, we can confirm where the problem is.

If the issue happens on the wired side as well on the controller:

#show interface <Port Type> <Port Id> --> Check the controller's uplink in which APs are communicating, See if there is port error and clear it

You can try rebooting the controller but only as a last resort to fix the issue.

Please share the results.

I should have mentioned that the PCAP was taken by mirroring the port on the switch that the controller is connected to, so we can be fairly certain the DHCP server is sending the packets and that the switch is forwarding them to the controller as we can see this in the capture.

The broadcast-filter option is not enabled.

The link between the switch and controller is a port channel and I have tried shutting down one of the links to see if the port-channel is the issue, although I didn't re-enable it and shut down the other interface to rule out a physical interface issue.

I think I will run an internal packet-capture on the controller to see if I can see the DHCP exchanges.

Can someone tell me if the DHCP exchanges are part of the datapath capture?

Try debugging from the WLC. 

#logging network process fpapps level debugging

#show logging level verbose
LOGGING LEVELS
--------------
Facility  Level     Sub Category  Process
--------  -----     ------------  -------
arm       warnings  N/A           N/A
network   debugging N/A           fpapps
security  warnings  N/A           N/A
system    warnings  N/A           N/A
user      warnings  N/A           N/A
wireless  warnings  N/A           N/A
#

and then you can either try:
show log all | include fpapps  or
show log all | include DHCP

Useful CLI commands can be found on: https://h20628.www2.hp.com/km-ext/kmcsdirect/emr_na-a00065463en_us-1.pdf

-------in the end, do not forget to stop debbuging-------

Hello!

Enabling "fpapps" might become processor overheading and it will include few other process logging as well.

If you are using 6.x, You could just use the below commands:

#logging level debugging network process dhcp

#logging level debugging network subcat dhcpd --> These above two commands will specifically enable the logs for the DHCP

#logging level debugging user-debug <mac-address> --> Enable the logs for the User/Device

If 8.x code,

"logging network process dhcp level debugging"

"logging network subcat dhcpd level debugging"

#show log all | include <current-date> --> Include filter could be helpful to filter the logs related to the Date or mac-address ("Dec 18")

#show log network all | include dhcp --> Will list all the DHCP process

#show log network all | include <mac-address> --> List all the logs related to the mac-address

Please try this and share us the result.