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300-425 · Question #235

A customer has a Cisco wireless network that has these configurations and components: - two Cisco Catalyst 9800 Series WLCs in a high availability cluster - 50 Cisco 2800I APs - all SSIDs and…

The correct answer is B. Set the XOR radio role to Monitor mode and the slot 1 radio to Client Serving on all the. On Cisco 2800I APs, setting the XOR radio to Monitor mode enables rogue scanning across both 2.4 GHz and 5 GHz, while leaving the dedicated slot 1 (5 GHz) radio in Client Serving mode preserves all existing 5 GHz-only SSIDs.

Monitoring and Troubleshooting

Question

A customer has a Cisco wireless network that has these configurations and components:

  • two Cisco Catalyst 9800 Series WLCs in a high availability cluster
  • 50 Cisco 2800I APs
  • all SSIDs and services are 5 GHz only

A security mandate requires that rogue APs be scanned and identified in 2.4 GHz and 5 GHz bands and must not impact existing client connectivity. How must the wireless network be reconfigured to meet the requirement without purchasing additional APs?

Options

  • ASet the XOR radio role to Client Serving and the slot 1 radio to Sniffer mode on all the
  • BSet the XOR radio role to Monitor mode and the slot 1 radio to Client Serving on all the
  • CSet the XOR radio role to Client Serving and the slot 1 radio to Monitor mode on all the
  • DSet the XOR radio role to Sniffer mode and the slot 1 radio to Client Serving on all the

How the community answered

(28 responses)
  • A
    14% (4)
  • B
    50% (14)
  • C
    7% (2)
  • D
    29% (8)

Why each option

On Cisco 2800I APs, setting the XOR radio to Monitor mode enables rogue scanning across both 2.4 GHz and 5 GHz, while leaving the dedicated slot 1 (5 GHz) radio in Client Serving mode preserves all existing 5 GHz-only SSIDs.

ASet the XOR radio role to Client Serving and the slot 1 radio to Sniffer mode on all the

Setting XOR to Client Serving and slot 1 to Sniffer leaves 2.4 GHz rogue detection uncovered, because slot 1 is a 5 GHz-only radio and Sniffer mode targets a single channel for packet capture rather than scanning for rogues.

BSet the XOR radio role to Monitor mode and the slot 1 radio to Client Serving on all theCorrect

The Cisco 2800I features an XOR radio that is software-configurable for either 2.4 GHz or 5 GHz and can be placed in Monitor mode to scan both bands for rogue devices without requiring additional APs. Slot 1 is a dedicated 5 GHz radio - keeping it in Client Serving mode ensures that all existing 5 GHz-only WLANs continue operating normally, satisfying both the security mandate and the connectivity requirement.

CSet the XOR radio role to Client Serving and the slot 1 radio to Monitor mode on all the

Setting slot 1 to Monitor mode only scans 5 GHz since it is a dedicated 5 GHz radio, failing to meet the requirement for 2.4 GHz rogue detection.

DSet the XOR radio role to Sniffer mode and the slot 1 radio to Client Serving on all the

Sniffer mode is designed for directed packet capture sent to a protocol analyzer such as Wireshark on a single channel, not for autonomous multi-channel, multi-band rogue AP scanning.

Concept tested: Cisco 2800 XOR radio Monitor mode for dual-band rogue detection

Source: https://www.cisco.com/c/en/us/td/docs/wireless/access_point/2800-3800/deployment/guide/b_cisco_aironet_series_2800_3800_access_point_deployment_guide.html

Topics

#rogue AP detection#XOR radio#monitor mode#Cisco 2800I

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