200-301 Question 207
Select 3A network engineer is configuring an EtherChannel between two switches using LACP. After configuring the EtherChannel, the engineer notices that the ports are not bundling into the channel group. Which of the following actions should the engineer take to resolve the issue?
- A
Ensure that the port modes on both switches are set to 'active' or 'active/passive'.
- B
Verify that the interfaces on both switches have identical speed and duplex settings.
- C
Enable PortFast on all interfaces participating in the EtherChannel.
- D
Check that the VLANs allowed on the trunk match on both switches.
- E
Configure all ports in the EtherChannel with the 'switchport mode access' command.
Show answer and explanation
Correct answers: A, B, D
Explanation
To successfully configure and verify an EtherChannel using LACP, it is crucial to ensure that the port modes are compatible (active/active or active/passive), the physical settings such as speed and duplex are identical across all interfaces in the channel, and the VLAN configurations match if the EtherChannel is a trunk. Mismatches in these settings are common causes of EtherChannel failures.
- A. Correct.
LACP requires the port modes to be compatible (e.g., 'active' or 'active/passive'). If the modes are not compatible, the EtherChannel will not form.
- B. Correct.
Interfaces participating in an EtherChannel must have identical speed and duplex settings. A mismatch here can prevent the channel from forming.
- C. Incorrect.
Enabling PortFast is not recommended on EtherChannel interfaces and does not play a role in LACP negotiation.
- D. Correct.
For trunk links, the VLANs allowed on the trunk must match on both switches to ensure proper LACP negotiation and traffic forwarding.
- E. Incorrect.
Setting all ports to 'switchport mode access' is not required or appropriate if the EtherChannel is configured as a trunk. This could break the channel configuration.