Configuring Active-Backup Bonding (Mode 1) for OLVM

Applies to: Oracle Linux 8 / 9, OLVM 4.x, mixed 10 Gb / 25 Gb networks

Overview

When LACP introduces instability, particularly with some 25 Gb optics or mixed vendor switches Active-Backup (mode 1) bonding provides a simpler and more reliable alternative.

Only one NIC is active at a time; the second automatically takes over if the primary fails.

This configuration requires no switch aggregation, making it highly resilient and straightforward to manage.

Architecture

ens1f0np0 (Primary)
ens1f1np1 (Backup)
      ↓
    bond0 (mode 1)
      ↓
  VLANs (bond0.11, bond0.20)

Step 1: Configure Cisco Switch

Unlike LACP, each NIC connects separately  do not use Port-Channels.

interface Ethernet1/22
  description OLVM-Host01-NIC1 (Primary)
  switchport
  switchport mode trunk
  switchport trunk allowed vlan 11,20
  spanning-tree port type edge trunk
  no shutdown

interface Ethernet1/23
  description OLVM-Host01-NIC2 (Backup)
  switchport
  switchport mode trunk
  switchport trunk allowed vlan 11,20
  spanning-tree port type edge trunk
  no shutdown

✅ Ensure:

• Same VLANs and MTU on both ports

• Both ports on same broadcast domain

• No channel-group commands

  
  

Step 2: Configure OLVM Host

# Create the bond
nmcli con add type bond ifname bond0 mode active-backup miimon 100 primary ens1f0np0

# Add both NICs
nmcli con add type ethernet ifname ens1f0np0 master bond0
nmcli con add type ethernet ifname ens1f1np1 master bond0

# Optional tuning
nmcli con mod bond0 bond.primary ens1f0np0
nmcli con mod bond0 bond.miimon 100

Create VLANs:

nmcli con add type vlan con-name bond0.11 dev bond0 id 11
nmcli con add type vlan con-name bond0.20 dev bond0 id 20

Assign IP:

nmcli con mod bond0.20 ipv4.addresses 10.178.7.83/24
nmcli con mod bond0.20 ipv4.gateway 10.178.7.1
nmcli con mod bond0.20 ipv4.method manual
nmcli con up bond0.20

Step 3: Verify Operation

cat /proc/net/bonding/bond0

Output example:

Bonding Mode: fault-tolerance (active-backup)
Primary Slave: ens1f0np0
Currently Active Slave: ens1f0np0
MII Status: up

If the primary link fails, the secondary (ens1f1np1) automatically becomes active.

Failover Test

Unplug the active interface or shut it down:

ip link set ens1f0np0 down
cat /proc/net/bonding/bond0

You should now see:

Currently Active Slave: ens1f1np1

Comparison: Mode 4 vs Mode 1

Feature	Mode 4 (LACP)	Mode 1 (Active-Backup)
Switch setup	Port-Channel required	Independent ports
Load balancing	Yes	No
Failover	Fast	Instant
Stability	Depends on switch & FEC	Very stable
Use case	Performance aggregation	High availability

Why Choose Active-Backup

In real-world OLVM clusters - especially using 25 Gb optics - Active-Backup has proven more reliable.

LACP can suffer from negotiation or aggregator mismatch issues, while Active-Backup simply uses whichever link is available, maintaining uptime with zero dependency on switch coordination.

Summary

Parameter	Value
Bond mode	active-backup
Primary	ens1f0np0
Secondary	ens1f1np1
Monitoring	miimon=100
VLANs	Trunked (11, 20)
Switch config	Standard trunk, no Port-Channel