Drag and Drop Question A network engineer is adding an additional 10Gps link to an exiting 2x10Gps LACP-based LAG to augment its capacity. Network standards require a bundle interface to be taken out

The correct answer is Execute the channel-group number mode active command to add the 10Gbps link to the existing bundle.; Execute the lacp min-bundle 3 command to set the minimum number of ports threshold.; Validate the network layer of the 10Gbps link.; Validate the physical and data link layers of the 10Gbps link.. LACP LAG Expansion - Exam Question Explained Background Context The engineer is expanding an existing LACP-based LAG (Link Aggregation Group) from 2x10Gbps to 3x10Gbps. Two constraints drive the solution: The bundle must go out of service if any member link fails (min-bundle requ

Submitted by anjalisingh· Mar 6, 2026Infrastructure

Question

Drag and Drop Question A network engineer is adding an additional 10Gps link to an exiting 2x10Gps LACP-based LAG to augment its capacity. Network standards require a bundle interface to be taken out of service if one of its member links goes down, and the new link must be added with minimal impact to the production network. Drag and drop the tasks that the engineer must perform from the left into the sequence on the right. Not all options are used. Answer:

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Drag items

Execute the channel-group number mode active command to add the 10Gbps link to the existing bundle.Execute the channel-group number mode on command to add the 10Gbps link to the existing bundle.Execute the lacp min-bundle 3 command to set the minimum number of ports threshold.Validate the network layer of the 10Gbps link.Execute the channel-group number mode auto command to add the 10Gbps link to the existing bundle.Validate the physical and data link layers of the 10Gbps link.

Correct arrangement

Execute the channel-group number mode active command to add the 10Gbps link to the existing bundle.
Execute the lacp min-bundle 3 command to set the minimum number of ports threshold.
Validate the network layer of the 10Gbps link.
Validate the physical and data link layers of the 10Gbps link.

Explanation

LACP LAG Expansion - Exam Question Explained

Background Context

The engineer is expanding an existing LACP-based LAG (Link Aggregation Group) from 2x10Gbps to 3x10Gbps. Two constraints drive the solution:

The bundle must go out of service if any member link fails (min-bundle requirement)
Changes must have minimal impact to the live network

Step-by-Step Placement Rationale

Step 1: channel-group number mode active

mode active is the correct LACP mode - it actively sends LACPDUs to negotiate link aggregation. The existing bundle already uses LACP, so the new member must use LACP as well. All members in a bundle must use the same protocol.

Why not mode on? This creates a static LAG with no LACP negotiation. You cannot mix mode on with LACP ports in the same bundle - it will cause the link to be suspended.

Why not mode auto? auto is PAgP (Cisco proprietary). The question explicitly states the LAG is LACP-based - mixing protocols is not possible.

Step 2: lacp min-bundle 3

This command sets the minimum number of active member links required for the bundle to remain in service. With min-bundle 3, if any one of the three links fails, the bundle is administratively taken down - satisfying the network standard.

Critical ordering reason: This command must come after adding the new link (Step 1). If you set min-bundle 3 while only 2 links are active, the bundle immediately goes out of service because it falls below the threshold. You'd disrupt a live production bundle unnecessarily.

Step 3: Validate the network layer

After configuration, you verify Layer 3 (IP connectivity, routing) across the bundle. This confirms the bundle is carrying traffic correctly and the network-level impact was minimal. This is a top-down confirmation: "Is the bundle still serving traffic?"

Step 4: Validate the physical and data link layers

After confirming the network layer is healthy, you drill down to verify the new link's Layer 1/2 status - confirming LACP negotiation succeeded, the link is in the correct LACP state (bundled), and the physical interface is error-free.

Common misconception: Students expect L1/L2 validation before L3, following the OSI model bottom-up. Here the order is top-down post-configuration verification: first confirm the live network is unaffected (L3), then verify the new member link's participation at lower layers. This is also a valid troubleshooting methodology - confirm the outcome, then confirm the mechanism.

Summary Table

Step	Action	Why Here
1	`mode active`	LACP-compatible mode; must match existing bundle protocol
2	`lacp min-bundle 3`	Must wait until 3rd link is in bundle or it kills the existing 2-link bundle
3	Validate network layer	Confirm live traffic is unaffected (minimal-impact check)
4	Validate physical/data link	Confirm the new member link is properly negotiated in the bundle

Not used: mode on (static, no LACP) and mode auto (PAgP, wrong protocol) - both are incompatible with an LACP bundle.

Topics

#LACP#EtherChannel#Network Configuration#High Availability

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