200-301 Question 208
Single answerA network administrator is configuring an EtherChannel using LACP between two switches, SwitchA and SwitchB. The administrator has verified that the cables are connected, and both switches support LACP. However, the EtherChannel is not forming. Which configuration step could resolve the issue?
- A
Ensure that the interfaces on both switches are set to LACP active mode.
- B
Change the port speed on one of the interfaces to be different from the others in the EtherChannel group.
- C
Disable LACP on one of the switches to force static EtherChannel.
- D
Verify that all interfaces in the EtherChannel group have the same VLAN configuration.
Show answer and explanation
Correct answer: A
Explanation
LACP (Link Aggregation Control Protocol) enables dynamic negotiation of EtherChannel. For LACP to form an EtherChannel, at least one side of the link must be set to 'active' mode, while the other can be set to either 'active' or 'passive'. If both sides are configured as 'passive', no negotiation occurs, and the EtherChannel will not form. Therefore, ensuring that one side is in 'active' mode resolves the issue.
- A. Correct.
LACP requires that at least one side of the link is in 'active' mode. If both sides are in 'passive' mode, the EtherChannel will not form.
- B. Incorrect.
All interfaces in an EtherChannel group must have matching settings (e.g., speed, duplex). Mismatched port speeds will prevent the EtherChannel from forming.
- C. Incorrect.
Disabling LACP will not resolve the issue and is not recommended, as it would result in a static EtherChannel configuration instead of LACP-based negotiation.
- D. Incorrect.
While matching VLAN configuration is required for EtherChannel to work, this is not specifically the issue described in the scenario.