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Zorluk: ZorWLAN Infrastructure Connections and LAG

An enterprise network deployment incorporates a Cisco Wireless LAN Controller (WLC) connected via four physical distribution system ports to a Cisco Catalyst switch stack. The network engineer enables Link Aggregation (LAG) globally on the controller and reboots the device. On the switch stack, the engineer attempts to establish the EtherChannel by configuring `channel-group 1 mode active` across ports GigabitEthernet 1/0/1 through 1/0/4. Following the WLC reboot, the controller loses all network management connectivity, and the switch logs indicate that the port-channel interface is down due to a negotiation failure. Which switch configuration modification will restore network connectivity while maintaining LAG operational on the controller?

  1. Change the channel group negotiation mode on all participating switch interfaces to mode on.Cevap
  2. B
    Change the negotiation protocol on the participating switch interfaces to channel-group 1 mode auto.
  3. C
    Divide the four physical links on the switch into two separate port-channels configured in mode on.
  4. D
    Reconfigure the participating physical switch interfaces as access ports assigned to the native VLAN.

Cevap

Change the channel group negotiation mode on all participating switch interfaces to mode on.
When Link Aggregation (LAG) is enabled on a Cisco Wireless LAN Controller (running AireOS), the controller bundles all physical distribution system ports into a single operational interface. AireOS controllers do not support dynamic link negotiation protocols such as Link Aggregation Control Protocol (LACP) or Port Aggregation Protocol (PAgP). Therefore, the connected interfaces on the upstream Cisco Catalyst switch must be configured as a static EtherChannel using `channel-group <id> mode on`.

Adım Adım Çözüm

1
Analyze the WLC Link Aggregation (LAG) signaling requirements.
Cisco AireOS Wireless LAN Controllers require static EtherChannel bundling without dynamic LACP or PAgP negotiation frames.
The controller firmware bundles all physical distribution system ports into a single non-negotiated logical port.
2
Identify the cause of the port-channel down state on the switch.
The switch was configured with `channel-group 1 mode active`, expecting LACP LACPDU negotiation packets that the WLC never sends.
Because LACP negotiation times out without receiving LACPDUs from the WLC, the switch keeps the port-channel in a suspended/down state.
3
Determine the necessary configuration change on the switch stack.
Change the interface configuration to `channel-group 1 mode on` across all attached switch ports.
Mode `on` forces the switch ports into a static EtherChannel bundle without waiting for negotiation frames.

Anahtar Kavram

WLAN Controller Link Aggregation (LAG) Switch Configuration Requirements
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Konular

WLAN Infrastructure Connections and LAG

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