200-301 Question 209
Single answerA network engineer is configuring EtherChannel using LACP between two switches, SwitchA and SwitchB. The engineer notices that the EtherChannel is not forming even though the configurations appear correct. Upon investigation, the engineer discovers that SwitchA is configured in 'active' mode and SwitchB is configured in 'passive' mode. What could be the reason for the EtherChannel not forming?
- A
Both switches must be configured in 'active' mode for the EtherChannel to form.
- B
LACP requires at least one switch to be in 'active' mode for the EtherChannel to form.
- C
The EtherChannel will only form if both switches are configured in 'passive' mode.
- D
The issue is unrelated to the LACP modes and is likely due to a physical connection problem.
Show answer and explanation
Correct answer: B
Explanation
In LACP, the EtherChannel can only form if at least one switch is in 'active' mode to initiate the negotiation process. If both switches are configured in 'passive' mode, neither will start the negotiation, and the EtherChannel will not form. In the scenario described, SwitchA is in 'active' mode and SwitchB is in 'passive' mode, which is a valid configuration for LACP to work. The issue is likely due to another misconfiguration or misunderstanding, but the LACP mode itself is not the problem.
- A. Incorrect.
This is incorrect because LACP does not require both switches to be in 'active' mode. One switch in 'active' mode is sufficient to form the EtherChannel.
- B. Correct.
This is correct because LACP requires at least one switch to be in 'active' mode to initiate the negotiation for the EtherChannel. In this case, SwitchA is in 'active' mode, and SwitchB in 'passive' mode is sufficient for the EtherChannel to form.
- C. Incorrect.
This is incorrect because LACP will not form an EtherChannel if both switches are in 'passive' mode. Passive mode does not initiate negotiation, so no communication would occur to form the EtherChannel.
- D. Incorrect.
This is incorrect because the issue described is specifically related to the LACP configuration. A physical connection problem would cause a different set of symptoms, such as no connectivity between the switches.