This document creates a network configuration to connect a Ubuntu server with a LACP trunk to a switch. The server should be accessible on a dedicated VLAN and there should be VLANs for containers and virtual machines.

The server’s network configuration is done using Netplan (tested on Ubuntu 22.04 LTS but should work in newer versions too). The switch configuration is for a Cisco switch but other switches can be used.

Ubuntu netplan configuration

The following netplan file creates:

• a LACP trunk with four physical interfaces
• three VLANs:
  • one for host access with a static IPv4 address
  • two to be used by containers and virtual machines
• two bridges to connect containers and virtual machines through VLANs

See the Notes section for some explanations.

network:
  version: 2
  renderer: networkd
  ethernets:
    eno1: {}
    eno2:
      optional: true
    eno3:
      optional: true
    eno4: 
      optional: true
  bonds:
    lacpbond:
      interfaces: [eno1, eno2, eno3, eno4]
      parameters:
        mode: 802.3ad
        lacp-rate: fast
        mii-monitor-interval: 100
        transmit-hash-policy: layer2
  vlans:
    vlanHost:
      id: 40
      link: lacpbond
      accept-ra: false
      addresses: [192.168.10.7/24]
      routes:
        - to: default
          via: 192.168.10.1
      nameservers:
        addresses:
          - 192.168.10.1
          - 8.8.8.8
        search: []
    vlan20:
      id: 20
      link: lacpbond
      accept-ra: false
    vlan21:
      id: 21
      link: lacpbond
      accept-ra: false
  bridges:
    net20:
      interfaces: [vlan20]
    net21:
      interfaces: [vlan21]

Example configuration for a Cisco switch

I have used these commands to set a compatible LACP trunk on a Cisco switch:

enable
configure terminal

port-channel load-balance src-dst-mac

default interface range GigabitEthernet0/5-8

interface range GigabitEthernet0/5-8
channel-group 3 mode active
exit

interface Port-channel 3
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk native vlan 3333
switchport trunk allowed vlan 40,20,21
end

Troubleshooting commands for Cisco LACP

debug lacp all
no debug lacp all
show etherchannel summary
show lacp 3 counters
show lacp 3 neighbor
show lacp 3 internal

Notes

LACP rate

Use lacp-rate: slow if the switch does not support fast LACP rate.

transmit-hash-policy

In this document I used the default layer2 load balancing but another method may be faster, depending on the workload.

transmit-hash-policy must be set according to the load balancing method configured on the switch. For more information see:

• xmit_hash_policy in Linux Ethernet Bonding Driver HOWTO abot transmit-hash-policy
• EtherChannel Load Balancing Explanation & Configuration for Cisco related load balancing