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Difficulty: MediumLayer 2 and Layer 3 EtherChannel (LACP)

A network engineer needs to configure a routed (Layer 3) EtherChannel bundle on a Cisco Catalyst switch using LACP active mode on physical interfaces GigabitEthernet0/1 and GigabitEthernet0/2, assigning the IP address 10.1.1.1/30 to the logical channel. In what sequential order should the configuration steps be executed on the switch CLI?

  1. 1Enter interface configuration mode for the physical interfaces using `interface range GigabitEthernet0/1 - 2`.
  2. 2Disable Layer 2 switching capabilities on the physical member interfaces using `no switchport`.
  3. 3Bind the physical member interfaces to logical group 10 using `channel-group 10 mode active`.
  4. 4Enter logical interface mode using `interface Port-channel 10` and configure the IP address `ip address 10.1.1.1 255.255.255.252`.

Answer

The correct execution order is: 1) Enter interface range configuration mode for GigabitEthernet0/1 - 2, 2) Execute 'no switchport' on member interfaces to convert them to Layer 3, 3) Issue 'channel-group 10 mode active' to initiate LACP, 4) Access 'interface Port-channel 10' and assign IP address 10.1.1.1 255.255.255.252.
Configuring a Layer 3 LACP EtherChannel follows a precise sequence: first select member physical interfaces (`interface range`), convert them from Layer 2 to Layer 3 (`no switchport`), assign them to the channel group with LACP negotiation (`channel-group 10 mode active`), and finally configure the IP address on the logical bundle (`interface Port-channel 10`).

Step-by-Step Solution

1
Select member physical interfaces using `interface range GigabitEthernet0/1 - 2`.
Enters range interface configuration mode context `(config-if-range)#`.
Allows simultaneous configuration of all member links intended for the EtherChannel bundle.
2
Execute `no switchport` on physical member interfaces.
Disables Layer 2 switchport operation on GigabitEthernet0/1 and GigabitEthernet0/2.
Layer 3 EtherChannels require member interfaces to operate as routed ports prior to group assignment so that Port-Channel 10 is dynamically spawned as a Layer 3 interface.
3
Execute `channel-group 10 mode active`.
Creates logical interface Port-channel 10 and enables LACP active negotiation on member ports.
The 'active' keyword configures LACP to actively send LACP packets to negotiate the channel with the peer device.
4
Enter `interface Port-channel 10` and assign `ip address 10.1.1.1 255.255.255.252`.
Assigns the IPv4 protocol configuration to the logical routed bundle.
In a routed EtherChannel, IP addresses are configured exclusively on the logical Port-channel interface, not on physical member links.

Key Concept

Layer 3 EtherChannel CLI Configuration and LACP Active Mode Negotiation Sequence
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Topics

Layer 2 and Layer 3 EtherChannel (LACP)

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