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Difficulty: HardLayer 2 and Layer 3 EtherChannel (LACP)

A network administrator needs to convert two physical switch interfaces (GigabitEthernet0/1 and GigabitEthernet0/2) on a Cisco Catalyst switch into a routed (Layer 3) EtherChannel bundle using dynamic LACP active mode. In what sequential order should the Cisco IOS configuration commands be executed to successfully establish the routed port-channel interface and configure its IP addressing?

  1. 1interface range GigabitEthernet0/1 - 2
  2. 2no switchport
  3. 3channel-group 10 mode active
  4. 4interface Port-channel 10
  5. 5ip address 10.10.10.1 255.255.255.252

Answer

The correct CLI configuration sequence is: enter physical interface range mode ('interface range GigabitEthernet0/1 - 2'), convert physical links to routed mode ('no switchport'), assign interfaces to dynamic LACP group ('channel-group 10 mode active'), enter logical port-channel mode ('interface Port-channel 10'), and assign the IP address ('ip address 10.10.10.1 255.255.255.252').
To build a routed (Layer 3) EtherChannel using LACP, an engineer must first enter physical interface configuration mode ('interface range GigabitEthernet0/1 - 2'), disable Layer 2 processing on those physical member links using 'no switchport', and bind them into an active LACP bundle with 'channel-group 10 mode active'. Once the bundle is formed, the engineer enters the logical interface mode ('interface Port-channel 10') and applies the IPv4 network parameters using 'ip address 10.10.10.1 255.255.255.252'.

Step-by-Step Solution

1
Select physical member interfaces using 'interface range GigabitEthernet0/1 - 2'
Enters interface range configuration mode for both physical ports simultaneously.
Configuration commands must target the physical interfaces that will compose the EtherChannel.
2
Disable Layer 2 functionality on physical links using 'no switchport'
Converts physical member interfaces from Layer 2 switchports to Layer 3 routed interfaces.
If interfaces remain in Layer 2 mode when assigned to a channel group, a Layer 2 port-channel will be created instead of a Layer 3 port-channel.
3
Bind physical interfaces into an LACP group using 'channel-group 10 mode active'
Creates logical Port-channel 10 and initiates LACP active negotiation on physical member links.
The 'active' keyword specifies dynamic LACP negotiation protocol mode.
4
Enter logical bundle interface configuration using 'interface Port-channel 10'
Moves CLI focus to the newly spawned logical interface Port-channel 10.
Layer 3 IP attributes must be configured on the parent logical bundle rather than individual member links.
5
Configure the IP address using 'ip address 10.10.10.1 255.255.255.252'
Assigns Layer 3 IPv4 addressing to Port-channel 10 for routing.
In a Layer 3 EtherChannel, routing parameters reside on the logical Port-channel interface.

Key Concept

Layer 3 LACP EtherChannel CLI Configuration Sequence
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Topics

Layer 2 and Layer 3 EtherChannel (LACP)

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