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Difficulty: MediumCisco Wireless Architectures and AP Modes

An enterprise network is deploying a centralized Cisco Wireless LAN Controller (WLC) solution based on the Split-MAC architecture. Which operational function is performed by the centralized WLC rather than the Lightweight Access Point (LAP)?

  1. Processing 802.11 client authentication requests and translating 802.11 frames to 802.3 Ethernet framesAnswer
  2. B
    Transmitting 802.11 beacon frames and responding directly to client probe requests
  3. C
    Generating real-time 802.11 MAC-level acknowledgments (ACKs) for received wireless frames
  4. D
    Buffering 802.11 data frames for wireless clients operating in power-save mode

Answer

Processing 802.11 client authentication requests and translating 802.11 frames to 802.3 Ethernet frames
Under Cisco's Split-MAC architecture, functions are split based on real-time sensitivity. Non-real-time management and control activities—such as processing client authentication, managing association states, and performing 802.11-to-802.3 frame translation—are handled centrally by the WLC.

Step-by-Step Solution

1
Analyze the Split-MAC architecture concept.
Recognize that wireless MAC functions are divided into real-time functions (handled by the LAP) and non-real-time functions (handled by the WLC).
Split-MAC optimizes performance by handling time-sensitive 802.11 tasks locally on the AP while centralizing management and higher-layer processing on the WLC.
2
Categorize the responsibilities of the Lightweight Access Point (LAP).
LAPs handle transmission of beacons, probe responses, immediate MAC layer acknowledgments (ACKs), RTS/CTS frame exchanges, and power-save buffering.
These tasks require immediate radio-level responses and cannot tolerate CAPWAP tunnel latency to a remote controller.
3
Categorize the responsibilities of the Wireless LAN Controller (WLC).
The WLC handles non-real-time management, 802.11 authentication/association, 802.1X/EAP processing, Radio Resource Management (RRM), and 802.11 to 802.3 frame translation.
Centralizing these functions allows uniform security policy enforcement and seamless mobility across the network.

Key Concept

Split-MAC Architecture Functional Division
Estimated Time:1m 0s
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Topics

Cisco Wireless Architectures and AP Modes

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