How to Configure EtherChannel with LACP
To configure EtherChannel: put the member ports into a channel-group with LACP active mode on both switches, then configure the logical port-channel interface. This bundles links for bandwidth and failover.
EtherChannel combines multiple links into one logical connection. See the EtherChannel lab.
Step 1: Add member ports to a channel-group (both switches)
interface range gi0/1 - 2channel-group 1 mode active | Both members join channel 1 via LACP — repeat on the other switch |
Step 2: Configure the logical port-channel
interface port-channel 1switchport mode trunk | Settings on the Po interface apply to all members consistently |
Step 3: Ensure matching settings
| Members must match speed, duplex, VLAN/trunk config | Mismatches prevent bundling (ports show individual) |
Verification
show etherchannel summary — the channel should show SU (Layer2, in use) with both ports marked (P) for bundled. Shut one member and traffic continues over the other, proving failover.
Frequently asked questions
How do I configure EtherChannel with LACP?
Put member ports in a channel-group with mode active on both switches, then configure the port-channel interface. Both sides must use compatible LACP modes.
What does mode active mean?
The port actively negotiates the bundle via LACP. active+active or active+passive forms a channel; passive+passive does not.
Why won't my ports bundle?
Usually mismatched member settings (speed, duplex, VLAN/trunk config) or incompatible channel modes between the two switches.
How do I verify EtherChannel?
show etherchannel summary — bundled ports show the (P) flag; the (I) individual flag indicates a configuration mismatch.
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