EtherChannel Configuration with Layer 3 Switches

Overview

This Packet Tracer lab demonstrates the configuration of EtherChannel on Layer 3 switches. EtherChannel bundles multiple physical links into a single logical link, enhancing bandwidth and providing redundancy. The switches in the topology are configured to use Layer 3 EtherChannel, which requires IP addresses on the port channels for inter-switch routing.

The lab includes:

• Configuring EtherChannel using Layer 3 (routed) port channels.
• Disabling switchport mode on the required interfaces.
• Enabling IP routing on each Layer 3 switch.

Network Topology

The network consists of three multi-layer switches (MSW1, MSW2, and MSW3) connected via EtherChannel. Each switch connects to the others using multiple Gigabit interfaces grouped into port channels. PCs are connected to each switch, but their IP addresses are not yet configured.

Switch Configurations

MSW1 Configuration

• Port Channel 1:
  • Interfaces: G1/0/1-3
  • IP Address: 192.168.3.253/24
• Port Channel 2:
  • Interfaces: G1/0/4-6
  • IP Address: 192.168.1.253/24

MSW2 Configuration

• Port Channel 1:
  • Interfaces: G1/0/1-3
  • IP Address: 192.168.3.254/24
• Port Channel 2:
  • Interfaces: G1/0/4-6
  • IP Address: 192.168.2.253/24

MSW3 Configuration

• Port Channel 1:
  • Interfaces: G1/0/1-3
  • IP Address: 192.168.1.254/24
• Port Channel 2:
  • Interfaces: G1/0/4-6
  • IP Address: 192.168.2.254/24

Steps to Configure EtherChannel with Layer 3 Switches

1. Enable IP Routing on Each Switch

To ensure that the switches can route between different networks, IP routing must be enabled.

Switch(config)# ip routing

2. Disable Switchport Mode on Interfaces

Since EtherChannel will operate at Layer 3, the interfaces must not be in switchport mode. For each group of interfaces, disable switchport mode.

Example for MSW1 (Port Channel 1, interfaces G1/0/1-3):

Switch(config)# interface range G1/0/1 - 3
Switch(config-if-range)# no switchport

Repeat for all the required interfaces on all switches.

3. Configure EtherChannel Groups

For each switch, group the appropriate interfaces into port channels using the channel-group command. For example, on MSW1:

• Port Channel 1: Group interfaces G1/0/1 - 3

  Switch(config)# interface range G1/0/1 - 3
  Switch(config-if-range)# channel-group 1 mode active

• Port Channel 2: Group interfaces G1/0/4 - 6

  Switch(config)# interface range G1/0/4 - 6
  Switch(config-if-range)# channel-group 2 mode active

4. Assign IP Addresses to the Port Channels

After configuring the port channels, assign IP addresses to the Layer 3 port-channel interfaces.

• For MSW1:

  • Port Channel 1 (192.168.3.253/24):

    Switch(config)# interface Port-channel 1
    Switch(config-if)# ip address 192.168.3.253 255.255.255.0
    Switch(config-if)# no shutdown

  • Port Channel 2 (192.168.1.253/24):

    Switch(config)# interface Port-channel 2
    Switch(config-if)# ip address 192.168.1.253 255.255.255.0
    Switch(config-if)# no shutdown

  Repeat this step for MSW2 and MSW3 using their respective port channels and IP addresses.

5. Verify the Configuration

• Check that the port channels are correctly configured and active:

  Switch# show etherchannel summary

• Verify that the IP addresses are correctly assigned to the port-channel interfaces:

  Switch# show ip interface brief

6. Assign IP Addresses to PCs (optional)

After completing the EtherChannel configuration, you can assign IP addresses to the PCs to allow for network testing.

---

Key Concepts

• EtherChannel: A technology that allows multiple physical links to be bundled into a single logical connection. This increases available bandwidth and provides redundancy.
• Layer 3 Switch: A device that can perform both switching (Layer 2) and routing (Layer 3) functions. Used to route traffic between different VLANs or networks.
• Port Channel: A virtual interface that represents the aggregated bundle of physical interfaces in an EtherChannel configuration.

---

Commands Summary

1. Enable IP Routing:

   ip routing

2. Disable Switchport Mode:

   no switchport

3. Configure EtherChannel:

   interface range G1/0/x - y
   channel-group <number> mode active

4. Assign IP Address:

   interface Port-channel<number>
   ip address <IP> <subnet mask>
   no shutdown

5. Verification:

   show etherchannel summary
   show ip interface brief

---

Conclusion

This lab demonstrates the step-by-step configuration of EtherChannel using Layer 3 switches. By disabling switchport mode and enabling IP routing, the switches can route traffic between different networks using logical port-channel interfaces. Once IP addresses are assigned to the PCs, further network tests can be conducted.

---