Controller Based WLANs

What does this AP reboot reason mean: “no reason given (called from udhcpc,sh)”?

by on ‎07-07-2014 01:14 PM

Question:  What does this AP reboot reason mean: “no reason given (called from udhcpc,sh)”?

 

Product and Software: This article applies to all Aruba controllers and ArubaOS versions.

If an access point reboots, you can find out why the AP rebooted in two ways:

  • Check the output on the AP console.
  • Use the command "show ap debug system-status ap-name <ap-name>" from the controller.

An AP can reboot for many reasons, but sometimes this message is shown:

"no reason given (called from udhcpc,sh)"

This reboot reason typically signifies that the AP is trying to renew its IP address and it receives a different or new IP address than the one it already holds.

To troubleshoot this scenario, try these steps:

  • Check DHCP server configuration.
  • Shorten the DHCP lease time (for example, 2 minutes) and do a packet capture on the uplink of the AP to see what IP address is being requested and sent.

The following test was performed to validate the reboot reason:

RAP5 terminates to a controller. RAP5 gets its IP address from a DHCP server in the same location.

1) The lease time was changed on the DHCP server to 2 minutes and a continuous Wireshark packet capture was performed on the DHCP server.

Every 1 minute, a DHCP REQUEST and DHCP ACK goes to and from the DHCP server. The exchange is basically the IP lease being renewed for the RAP.

2) Then, that IP address was removed from the DHCP server, so that it is forced to supply the RAP with a different IP address.

The RAP tried to renew its lease by sending 10 DHCP packets, but the DHCP server did not ACK because it no longer could supply that IP address.

The RAP then sent a DHCP discover packet, obtained a new IP address, and rebooted. The reboot reason given was "no reason given (called from udhcpc,sh)".

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