Cisco

Configuring EtherChannel with LCAP Between Two Switches

13 Jul 2025 — 2 min read

It's common to connect switches using multiple cables to improve redundancy and bandwidth. However, without proper configuration, this can lead to loops, broadcast storms, and blocked ports due to Spanning Tree Protocol (STP)

That's where EtherChannel with LACP (Link Aggregation Control Protocol) comes in. It lets you bundle multiple physical links into one logical link that's loop-free, redundant, and load-balanced and best of all, STP treats it as a single path.

In this lab, we will configure EtherChannel using LACP between two switches. You'll learn how to combine interfaces, configure negotiation, and see how STP interacts with the channel.

Requirements

2x 2960 Cisco Switches
2x Ethernet cable

Step 1: Connect the Switches

Use the straight-through cable between:

Fa0/1 and Fa0/2 on Switch 1
to Fa0/1 and Fa0/2 on Switch 2

Your topology should look something like this:

Don't worry about the circles, I just put them in there so I know they are going to be EtherChannels.

Step 2: Create the EtherChannel Group

We'll configure LACP with mode active and mode passive

On Switch 1:

enable
configure terminal
interface range fa0/1-2
channel-group 1 mode active
exit
exit
write memory

On Switch 2:

enable
configure terminal
interface range fa0/1-2
channel-group 1 mode passive
exit
exit
write memory

LACP requires at least one side to be active. Active tries to negotiate, while passive waits for the other side.

Step 3: Configure the Port-Channel Interface

Now we can configure the logical interface created by EtherChannel

On Both Switches:

enable
configure terminal
interface port-channel 1
switchport mode trunk
exit
exit
write memory

This trunk allows VLAN traffic to flow between switches across the bundled links.

Step 4: Verify EtherChannel

Use this commands to check if the bundle is up:

show etherchannel summary

You should see something like:

This states:

Po1: Port-channel 1
SU: Layer 2, in use
P: Port is bundled in the channel

Step 5: Verify STP Sees One Link

Let's see what Spanning-tree is saying to us.

show spanning-tree

You should only see one active forwarding link, STP sees the EtherChannel as a single logical connection.

Port 27 (Port-channel1) Is being used as the forwarding interface.
Role: Root - This switch see Po1 as the best path toward the root bridge.
Sts: FWD - The link is forwarding traffic.
Cost: 12 - The total STP Path cost for this logical link

Conclusion

We have built a stable and redundant link between two switches using EtherChannel with LCP. We have tested it and saw how STP treats the bundle as a single logical interface.

I hope you enjoyed this guide and Happy Networking!

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