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Difficulty: MediumLayer 2 and Layer 3 EtherChannel (LACP)

A network administrator is attempting to establish an operational Layer 3 EtherChannel using LACP between two Cisco switches. After applying the initial configuration, the administrator issues the `show etherchannel summary` command on Switch1 and observes the following output:

Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby s - Layer2
R - Layer3 U - in use

Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SD) LACP Gi0/1(D) Gi0/2(D)

Which configuration change on Switch1 is required to allow Port-Channel 1 to operate successfully as a Layer 3 EtherChannel?

  1. Configure the `no switchport` command on physical member interfaces GigabitEthernet0/1 and GigabitEthernet0/2 before adding them to the channel group.Answer
  2. B
    Change the LACP mode on physical member interfaces GigabitEthernet0/1 and GigabitEthernet0/2 from `active` to `desirable`.
  3. C
    Configure the channel group mode to `passive` on both switches to initialize LACP negotiation.
  4. D
    Set matching native VLANs on GigabitEthernet0/1 and GigabitEthernet0/2 to enable Layer 3 packet transmission.

Answer

Configure the `no switchport` command on physical member interfaces GigabitEthernet0/1 and GigabitEthernet0/2 before adding them to the channel group.
For a Layer 3 EtherChannel to operate correctly, physical member interfaces must be explicitly configured as routed ports using the `no switchport` command. The flag `S` in `Po1(SD)` indicates the interface bundle is operating at Layer 2. Converting the physical member ports to Layer 3 allows the EtherChannel to transition to the `RU` (Layer 3, in use) operational state.

Step-by-Step Solution

1
Analyze the output flags from `show etherchannel summary`.
The logical interface displays `Po1(SD)`, where `S` indicates Layer 2 operational mode and `D` indicates the channel is Down. Member interfaces display `(D)` for down.
The flag `S` indicates the physical interfaces are currently operating as Layer 2 switchports rather than Layer 3 routed ports.
2
Identify the requirement for creating a Layer 3 EtherChannel in Cisco IOS.
Both the physical member interfaces and the logical port-channel interface must be configured with `no switchport` to function as routed interfaces.
If physical interfaces remain in Layer 2 switchport mode, the port-channel cannot bundle them into a Layer 3 (`R`) operational state.
3
Determine the corrective CLI commands.
Navigate to `interface range GigabitEthernet0/1 - 2` and execute `no switchport`, then re-assign `channel-group 1 mode active`.
Disabling switchport mode allows the interfaces to negotiate as Layer 3 routed ports and transition the port-channel state flag from `SD` to `RU` (Layer 3, in use).

Key Concept

Layer 3 EtherChannel Member Configuration
Estimated Time:1m 30s
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Topics

Layer 2 and Layer 3 EtherChannel (LACP)

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