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Difficulty: HardLayer 2 and Layer 3 EtherChannel (LACP)

A network administrator is establishing a dynamic IEEE 802.3ad Link Aggregation Control Protocol (LACP) Layer 2 EtherChannel bundle between two Cisco Catalyst switches. Physical member interfaces GigabitEthernet1/0/1 and GigabitEthernet1/0/2 are being assigned to channel-group 5. Which two configuration conditions or operational requirements must be satisfied on the local and remote switches for the EtherChannel to successfully negotiate and operationalize both member links? (Select two.)

  1. All physical member interfaces within the channel group on a switch must match in speed, duplex mode, and trunking configuration (VLAN membership and native VLAN).Answer
  2. At least one side of the link must be set to LACP active mode, while the opposing side is configured in either active or passive mode.Answer
  3. C
    The local switch must be configured with a numerically lower LACP system priority than the remote switch before negotiation can begin.
  4. D
    Individual IPv4 addresses must be configured on GigabitEthernet1/0/1 and GigabitEthernet1/0/2 before adding them to channel-group 5.

Answer

The two correct requirements are: 1) Physical member interfaces on a switch must match in speed, duplex, and trunking parameters, and 2) At least one side of the link must be configured in active LACP mode while the opposing side is set to active or passive mode.
The options specifying interface parameter consistency (speed, duplex, trunking settings) and LACP active/passive mode matching are correct. LACP requires physical port settings to be identical across members on the same switch, and at least one connected switch interface must be set to LACP active mode to initiate the 802.3ad negotiation sequence.

Step-by-Step Solution

1
Analyze LACP negotiation protocol requirements
LACP (802.3ad) uses active and passive negotiation modes. Active ports send LACP packets to initiate negotiation, while passive ports only respond to received LACP packets. If both sides are passive, no frames are sent and the EtherChannel fails to negotiate.
Determining dynamic channel formation rules requires evaluating LACP mode compatibility pairings (active-active or active-passive).
2
Verify physical interface parameter consistency
EtherChannel member interfaces must maintain identical speed, duplex, ST P settings, native VLAN, allowed VLANs, and access VLAN assignments. Incompatibilities cause individual ports to be put in an unbundled or suspended state.
Consistency across member interfaces prevents Layer 2 loops and blackholing of switched traffic.
3
Evaluate invalid distractor statements regarding IP configuration and LACP priority
LACP system priority defaults to 32768 and only comes into play during hot-standby port selection when bundling more links than allowed by hardware limits. IP addresses belong on the Port-channel interface for Layer 3 setups, not physical member ports.
Distinguishing essential prerequisites from optional tuning features eliminates false prerequisites.

Key Concept

LACP Interface Consistency and Mode Pairing Requirements
Estimated Time:2m 0s
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Topics

Layer 2 and Layer 3 EtherChannel (LACP)

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