mediumMultiple ChoiceObjective-mapped
LACP Active and Passive Mode Negotiation
Consider the following configuration snippet:
interface Port-channel1 switchport mode trunk switchport trunk allowed vlan 10,20,30
!
interface GigabitEthernet0/1 channel-group 1 mode active
!
interface GigabitEthernet0/2 channel-group 1 mode passive
What is the effect of this configuration?
Quick Answer
The correct answer is that the EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30. This works because LACP active and passive mode negotiation allows a link to be established as long as at least one side is set to active; the active side initiates the LACP packets, while the passive side listens and responds, so the channel forms successfully. On the ENCOR 350-401 exam, this question tests your understanding of LACP negotiation states and how they interact with port-channel interface configurations—a common trap is assuming both sides must be active, but passive is perfectly fine as a responder. Remember that the port-channel interface inherits all Layer 2 settings, such as trunking and allowed VLANs, from the interface-level configuration. A helpful memory tip: “Active initiates, passive participates—one must talk for the link to walk.”
⚠ Common exam trap
Cisco often tests the misconception that both sides of an LACP EtherChannel must use the same mode (active/active or passive/passive), but in fact active/passive works, while passive/passive does not form a channel.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30.
The configuration uses LACP with one side in active mode (GigabitEthernet0/1) and the other in passive mode (GigabitEthernet0/2). LACP allows an active/passive combination to form an EtherChannel, unlike PAgP which requires at least one side to be in desirable mode. The trunk and allowed VLANs are configured on the port-channel interface, which applies to all member ports once the channel is established.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30.
Why this is correct
Correct. LACP active/passive will negotiate, and the port-channel trunk configuration applies to all member ports.
- ✗
The EtherChannel will not form because both sides must use the same LACP mode.
Why it's wrong here
Incorrect. LACP active/passive is a valid combination; the active side initiates negotiation.
- ✗
The EtherChannel will form using PAgP because the mode is not specified as lacp.
Why it's wrong here
Incorrect. The 'channel-group 1 mode active' command explicitly uses LACP, not PAgP.
- ✗
The EtherChannel will form but only VLAN 1 will be allowed on the trunk.
Why it's wrong here
Incorrect. The 'switchport trunk allowed vlan' command restricts the trunk to VLANs 10, 20, and 30.
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Same concept, more angles
1 more way this is tested on 350-401
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Given the configuration: interface Port-channel1 switchport mode trunk switchport trunk allowed vlan 10-20 ! interface GigabitEthernet0/1 switchport mode trunk channel-group 1 mode passive ! interface GigabitEthernet0/2 switchport mode trunk channel-group 1 mode passive What is missing for this EtherChannel to form with a neighbor that uses LACP active?
medium- A.The member interfaces must also have the 'switchport trunk allowed vlan 10-20' command.
- B.The port-channel interface must be configured with 'channel-group 1' to associate the member ports.
- ✓ C.Nothing is missing; the configuration is valid and the EtherChannel will form with the neighbor.
- D.The member interfaces must use LACP active mode to form the channel.
Why C: The configuration is valid because LACP uses a negotiation system where one side must be in active mode and the other in passive mode to form an EtherChannel. Here, the neighbor is configured with LACP active, and the local member interfaces are configured with 'channel-group 1 mode passive', which is the correct counterpart. The 'switchport trunk allowed vlan' command is only needed on the port-channel interface, not on the member interfaces, as the port-channel interface inherits and propagates the VLAN list to the member ports.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.