300-370 · Question #11
A wireless engineer is unable to join lightweight access points to the Cisco Wireless Controller. The access points receive ip addresses from a DHCP pool configured on the core switch. Which action…
The correct answer is B. Configure option 43 on the DHCP pool. To resolve lightweight access points (LAPs) failing to join a Cisco Wireless Controller (WLC) when receiving IP addresses from DHCP, you must configure DHCP Option 43. This option provides the WLC's management IP address to the LAPs, enabling them to discover the controller.
Question
A wireless engineer is unable to join lightweight access points to the Cisco Wireless Controller. The access points receive ip addresses from a DHCP pool configured on the core switch. Which action must be taken to resolve the issue?
Options
- AUpgrade the Wireless Controller to a newer IOS release.
- BConfigure option 43 on the DHCP pool.
- CConfigure option 82 on the Wireless controller.
- DChange the management ip address on the Wireless Controller.
How the community answered
(29 responses)- A3% (1)
- B90% (26)
- C3% (1)
- D3% (1)
Why each option
To resolve lightweight access points (LAPs) failing to join a Cisco Wireless Controller (WLC) when receiving IP addresses from DHCP, you must configure DHCP Option 43. This option provides the WLC's management IP address to the LAPs, enabling them to discover the controller.
Upgrading the Wireless Controller to a newer IOS release is a general troubleshooting step that might fix bugs but does not directly address the AP discovery mechanism provided by DHCP Option 43.
DHCP Option 43 is a vendor-specific option that Cisco lightweight access points use to discover the IP address of the Wireless LAN Controller. By configuring this option in the DHCP pool, APs receive the WLC's IP address, allowing them to establish a Control And Provisioning of Wireless Access Points (CAPWAP) tunnel and join the controller.
DHCP Option 82 is used for relay agent information (e.g., circuit ID, remote ID) for security or management purposes, not for WLC discovery by access points.
Changing the management IP address on the Wireless Controller without a corresponding discovery mechanism configured for the APs would likely break existing connections or prevent new ones, rather than resolve the issue.
Concept tested: Cisco WLC AP discovery via DHCP Option 43
Source: https://www.cisco.com/c/en/us/support/docs/wireless/4400-series-wireless-lan-controllers/107530-dhcp-option-43-00.html
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