Lab Objective
Configure a Layer 3 EtherChannel between two Layer 3-capable switches, assigning an IP address directly to the port-channel interface rather than to individual physical interfaces, and verify OSPF forms exactly one neighbor relationship across the bundled link rather than treating each physical member as a separate path.
Lab Purpose
Every EtherChannel configured earlier in this series was a Layer 2 switched bundle. A Layer 3 EtherChannel instead combines multiple physical links into a single routed interface, useful for high-bandwidth links between distribution or core Layer 3 switches where the connection needs an IP address directly rather than functioning as a VLAN trunk.
Lab Topology
Switch1 (Layer 3 capable) ---- Gi1/0/1, Gi1/0/2 ----
Switch2 (Layer 3 capable)
Po1 on Switch1: 10.99.1.1/30
Po1 on Switch2: 10.99.1.2/30Task 1: Configure the Physical Interfaces as Layer 3 Channel Members
Remove any switchport configuration from Gi1/0/1 and Gi1/0/2 on both switches, and bundle them into a Layer 3 port-channel.
Task 2: Assign an IP Address to the Port-Channel Interface
Configure the IP address directly on Po1 on both switches, rather than on any individual physical interface.
Task 3: Verify the Bundle Formed Correctly
Confirm both member links are bundled and active.
Task 4: Verify Basic Connectivity
Ping between the two Po1 addresses.
Task 5: Enable OSPF and Verify a Single Neighbor Relationship
Enable OSPF on the Po1 interfaces and confirm exactly one neighbor forms, not two.
Solution and Verification
Switch1(config)# interface range gigabitethernet1/0/1-2
Switch1(config-if-range)# no switchport
Switch1(config-if-range)# channel-group 1 mode active
-- "no switchport" is what makes this a
-- Layer 3 bundle rather than the Layer 2
-- switched bundles configured in earlier
-- EtherChannel labsSwitch2(config)# interface range gigabitethernet1/0/1-2
Switch2(config-if-range)# no switchport
Switch2(config-if-range)# channel-group 1 mode activeSwitch1(config)# interface port-channel 1
Switch1(config-if)# ip address 10.99.1.1 255.255.255.252
Switch1(config-if)# no shutdownSwitch2(config)# interface port-channel 1
Switch2(config-if)# ip address 10.99.1.2 255.255.255.252
Switch2(config-if)# no shutdownSwitch1# show etherchannel summary
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------
1 Po1(RU) LACP Gi1/0/1(P) Gi1/0/2(P)
-- "R" in the flags indicates this is a
-- Layer 3 (routed) port-channel, distinct
-- from the "S" (switched/Layer 2) flag
-- seen in earlier EtherChannel labsSwitch1# ping 10.99.1.2
!!!!!
Success rate is 100 percent (5/5)Switch1(config)# router ospf 1
Switch1(config-router)# network 10.99.1.0 0.0.0.3 area 0
Switch2(config)# router ospf 1
Switch2(config-router)# network 10.99.1.0 0.0.0.3 area 0Switch1# show ip ospf neighbor
Neighbor ID Pri State Address Interface
2.2.2.2 1 FULL/ - 10.99.1.2 Port-channel1
-- Exactly one neighbor relationship formed
-- over the single logical Port-channel1
-- interface, rather than OSPF attempting to
-- form separate adjacencies over Gi1/0/1
-- and Gi1/0/2 individuallyKey Takeaway
The no switchport command is the single defining difference that converts an EtherChannel from a Layer 2 switched bundle into a Layer 3 routed one — once configured this way, the IP address and any routing protocol configuration belongs entirely on the logical Port-channel interface, never on the individual physical members, exactly mirroring how VLAN and trunk settings were applied to the logical bundle rather than individual members in the Layer 2 EtherChannel labs covered earlier in this series.