LACP configuration 3

Topology

Tasks:

A data center has two core switches, CoreSW1 and CoreSW2, that require a high-availability connection for efficient traffic flow and redundancy. LACP (Link Aggregation Control Protocol) will be used to aggregate multiple links between the switches into a single logical interface.

  1. Configure the links between CoreSW1 and CoreSW2 as a 802.1Q trunk.
  2. Configure VLANs 30 and 40 to be tagged across the link.
  3. Configure VLAN 20 as untagged VLAN.
  4. Add both the interfaces into etherchannel 10 using LACP (Link Aggregation Control Protocol). Both sides must initiate negotiation.

Solution:

Task 1: Configure the links between CoreSW1 and CoreSW2 as a 802.1Q trunk.

On CoreSW1:

CoreSW1# configure terminal
CoreSW1(config)# interface range f0/1-2
CoreSW1(config-if-range)# switchport trunk encapsulation dot1q
CoreSW1(config-if-range)# switchport mode trunk

On CoreSW2:

CoreSW2# configure terminal
CoreSW2(config)# interface range f0/1-2
CoreSW2(config-if-range)# switchport trunk encapsulation dot1q
CoreSW2(config-if-range)# switchport mode trunk

The interface range command allows us to configure the interfaces collectively which can save a lot of time. switchport trunk encapsulation dot1q specifies the use of IEEE 802.1Q for VLAN tagging.

 

Task 2: Configure only VLANs 30 and 40 to be tagged across the link.

To configure VLANs 30 and 40 to be tagged across the link, we need to allow them on the trunk links.

On CoreSW1:

CoreSW1(config-if)# switchport trunk allowed vlan 30,40

On CoreSW2:

CoreSW2(config-if)# switchport trunk allowed vlan 30,40

 

Task 3: Configure VLAN 20 as untagged VLAN.

To configure VLAN 20 to be untagged across the link, we need set it as the native VLAN on the trunk links. A native VLAN is not tagged by a trunk port.

On CoreSW1:

CoreSW1(config-if)# switchport trunk native vlan 20

On CoreSW2:

CoreSW2(config-if)# switchport trunk native vlan 20

 

Task 4: Add both the interfaces into etherchannel 10 using LACP (Link Aggregation Control Protocol). Both sides must initiate negotiation.

Combine Fa0/1 and Fa0/2 into a single EtherChannel using LACP on both switches. Both sides will initiate LACP negotiation by using the active mode.

On CoreSW1:

CoreSW1(config-if-range)# channel-group 10 mode active
CoreSW1(config-if-range)# end

On CoreSW2:

CoreSW2(config-if-range)# channel-group 10 mode active
CoreSW2(config-if-range)# end

channel-group 10 mode active command will combine both the interfaces into an etherchannel with number 10. All the configurations under fa0/1 and fa0/2 will be copied under the port-channel 10.

 

Verifcation:

Use the show etherchannel summary command on both switches to verify.

On CoreSW1:

CoreSW1# show etherchannel summary

--output omitted--

Group  Port-channel  Protocol    Ports

------+-------------+-----------+----------------------------------------------

1      Po10(SU)          LACP   Fa0/1(P) Fa0/2(P)

On CoreSW2:

CoreSW2# show etherchannel summary

--output omitted--

Group  Port-channel  Protocol    Ports

------+-------------+-----------+----------------------------------------------

1      Po10(SU)          LACP    Fa0/1(P) Fa0/2(P)

"SU" means that etherchannel formation was successful.

Now save the configuration.

CoreSW1# write memory

CoreSW2# write memory

 

Packet Tracer File

Clicking this button will begin the download of a ZIP file. Inside the ZIP file, you'll find a Packet Tracer Activity (.pka) file, which will automatically track your progress as you configure the network.

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