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Zorluk: Çok zorWLAN Infrastructure Connections and LAG

An enterprise wireless administrator is integrating a Cisco 5520 Wireless LAN Controller (running AireOS) with a Cisco Catalyst switch stack. The administrator connects four physical distribution system ports on the controller to switch interfaces GigabitEthernet1/0/1 through 1/0/4. The switch interfaces are configured as an 802.1Q trunk bundle using the command `channel-group 1 mode active`. Although Link Aggregation (LAG) has been enabled on the WLC and the controller has been rebooted, the EtherChannel fails to form and all controller distribution links remain down. Which modification on the Catalyst switch stack will resolve this connection failure?

  1. Change the negotiation protocol on the switch interfaces by executing `channel-group 1 mode on`.Cevap
  2. B
    Reconfigure the switch interface range using `channel-group 1 mode desirable` to enable Cisco proprietary PAgP negotiation.
  3. C
    Convert all connected Lightweight APs to FlexConnect mode to allow the controller distribution system ports to initiate LACP negotiations.
  4. D
    Change the native VLAN on the switch trunk interfaces to VLAN 1 so that LACP control frames can pass untagged across the bundle.

Cevap

Change the switch port EtherChannel configuration to static ON mode using `channel-group 1 mode on`.
When Link Aggregation (LAG) is enabled on a Cisco AireOS Wireless LAN Controller, all physical distribution system ports are merged into a single logical interface. AireOS controllers do not support dynamic negotiation protocols such as Link Aggregation Control Protocol (LACP) or Port Aggregation Protocol (PAgP). Therefore, the connected switch ports must be explicitly configured with static link aggregation using the command `channel-group <id> mode on`. Configuring `mode active` forces the switch to expect LACP frames, which the WLC will never transmit, causing the channel to remain down.

Adım Adım Çözüm

1
Identify the controller platform and operating system requirements for Link Aggregation (LAG).
Cisco AireOS Wireless LAN Controllers require static EtherChannel bonding across all active distribution system ports.
AireOS software does not support dynamic link aggregation protocols such as LACP (`mode active`/`mode passive`) or PAgP (`mode desirable`/`mode auto`).
2
Analyze the current switch configuration.
The switch interfaces are set to `channel-group 1 mode active`, which requires LACP negotiation packets from the connected device.
Because the AireOS WLC never sends LACP frames, the switch ports remain suspended in an unbundled state awaiting negotiation.
3
Determine the necessary configuration change on the switch ports.
Change `channel-group 1 mode active` to `channel-group 1 mode on` on all connecting interfaces.
Configuring `mode on` disables negotiation protocol requirements and forces the switch interfaces into a functional EtherChannel bundle matching the WLC behavior.

Anahtar Kavram

WLAN Controller Link Aggregation (LAG) EtherChannel Switch Configuration
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Konular

WLAN Infrastructure Connections and LAG

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