Bond Configuration¶

What is Bonding?¶

Bonding (also called link aggregation or NIC teaming) combines multiple physical interfaces into one logical interface for:

Redundancy - Failover if one link fails
Increased bandwidth - Aggregate throughput
Load balancing - Distribute traffic across links

┌─────────────────────────────────────────────────────────────┐
│                    Bond (bond0)                              │
│                   192.168.1.100/24                          │
│                                                              │
│   ┌──────────────────┐      ┌──────────────────┐           │
│   │      enp5s0      │      │      enp6s0      │           │
│   │   (1 Gbps NIC)   │      │   (1 Gbps NIC)   │           │
│   └────────┬─────────┘      └────────┬─────────┘           │
└────────────┼─────────────────────────┼─────────────────────┘
             │                         │
             └───────────┬─────────────┘
                         │
                    To Switch
                  (2 Gbps combined)

Bond Modes¶

Mode	Name	Description	Requires
0	balance-rr	Round-robin	Switch support (EtherChannel)
1	active-backup	Failover only	Nothing
2	balance-xor	XOR hash balancing	Switch support
3	broadcast	Send on all slaves	Switch support
4	802.3ad	LACP	Switch LACP support
5	balance-tlb	Adaptive transmit	Nothing
6	balance-alb	Adaptive load	Nothing

Mode Recommendations¶

Use Case	Recommended Mode
Simple failover	active-backup (1)
Maximum throughput with LACP switch	802.3ad (4)
Load balance without switch support	balance-alb (6)
Server-to-server direct connect	balance-rr (0)

Basic Bond Configuration¶

Active-Backup (Failover)¶

Simplest and most compatible:

network:
  version: 2
  renderer: networkd

  ethernets:
    enp5s0:
      dhcp4: false
    enp6s0:
      dhcp4: false

  bonds:
    bond0:
      interfaces:
        - enp5s0
        - enp6s0
      addresses:
        - 192.168.1.100/24
      routes:
        - to: default
          via: 192.168.1.1
      parameters:
        mode: active-backup
        primary: enp5s0
        mii-monitor-interval: 100

LACP (802.3ad)¶

For managed switches with LACP:

network:
  version: 2

  ethernets:
    enp5s0:
      dhcp4: false
    enp6s0:
      dhcp4: false

  bonds:
    bond0:
      interfaces:
        - enp5s0
        - enp6s0
      addresses:
        - 192.168.1.100/24
      routes:
        - to: default
          via: 192.168.1.1
      parameters:
        mode: 802.3ad
        lacp-rate: fast
        mii-monitor-interval: 100
        transmit-hash-policy: layer3+4

Balance-ALB (No Switch Config Needed)¶

network:
  version: 2

  ethernets:
    enp5s0:
      dhcp4: false
    enp6s0:
      dhcp4: false

  bonds:
    bond0:
      interfaces:
        - enp5s0
        - enp6s0
      addresses:
        - 192.168.1.100/24
      routes:
        - to: default
          via: 192.168.1.1
      parameters:
        mode: balance-alb
        mii-monitor-interval: 100

Bond Parameters¶

MII Monitor¶

Link health monitoring:

parameters:
  mii-monitor-interval: 100    # Check every 100ms
  up-delay: 200                # Wait 200ms before marking up
  down-delay: 200              # Wait 200ms before marking down

ARP Monitor¶

Alternative to MII monitoring:

parameters:
  arp-interval: 1000           # Check every 1000ms
  arp-ip-targets:
    - 192.168.1.1              # Ping gateway
    - 192.168.1.2              # Ping another host
  arp-validate: all            # Validate on all slaves
  arp-all-targets: all         # All targets must respond

Primary Interface¶

For active-backup mode:

parameters:
  mode: active-backup
  primary: enp5s0              # Preferred active interface
  primary-reselect-policy: always  # Reselect when primary returns

Reselect policies: - always - Switch back when primary returns - better - Switch back if primary is better - failure - Only switch on failure

Hash Policy¶

For 802.3ad and balance-xor:

parameters:
  mode: 802.3ad
  transmit-hash-policy: layer3+4  # Hash by IP + port

Hash policies: - layer2 - Source/dest MAC - layer2+3 - MAC + IP - layer3+4 - IP + port (recommended for most cases) - encap2+3 - Encapsulated layer 2+3 - encap3+4 - Encapsulated layer 3+4

LACP Rate¶

parameters:
  mode: 802.3ad
  lacp-rate: fast    # LACPDUs every 1 second
  # lacp-rate: slow  # LACPDUs every 30 seconds (default)

Fail Over MAC¶

For active-backup:

parameters:
  mode: active-backup
  fail-over-mac-policy: active  # Use active slave's MAC

Policies: - none - Bond uses fixed MAC (default) - active - Bond uses active slave's MAC - follow - Each slave uses bond's MAC

Bond with DHCP¶

network:
  version: 2

  ethernets:
    enp5s0:
      dhcp4: false
    enp6s0:
      dhcp4: false

  bonds:
    bond0:
      interfaces:
        - enp5s0
        - enp6s0
      dhcp4: true
      parameters:
        mode: active-backup
        mii-monitor-interval: 100

Bond + Bridge¶

Common for VM hosts:

network:
  version: 2

  ethernets:
    enp5s0:
      dhcp4: false
    enp6s0:
      dhcp4: false

  bonds:
    bond0:
      interfaces:
        - enp5s0
        - enp6s0
      parameters:
        mode: 802.3ad
        lacp-rate: fast
        mii-monitor-interval: 100
        transmit-hash-policy: layer3+4
      # No IP here - IP goes on bridge

  bridges:
    br0:
      interfaces:
        - bond0
      addresses:
        - 192.168.1.100/24
      routes:
        - to: default
          via: 192.168.1.1
      parameters:
        stp: false

Bond + VLAN¶

network:
  version: 2

  ethernets:
    enp5s0:
      dhcp4: false
    enp6s0:
      dhcp4: false

  bonds:
    bond0:
      interfaces:
        - enp5s0
        - enp6s0
      parameters:
        mode: 802.3ad
        lacp-rate: fast
        mii-monitor-interval: 100

  vlans:
    bond0.100:
      id: 100
      link: bond0
      addresses:
        - 192.168.100.1/24

    bond0.200:
      id: 200
      link: bond0
      addresses:
        - 192.168.200.1/24

Bond + VLAN + Bridge¶

Full stack:

network:
  version: 2

  ethernets:
    enp5s0:
      dhcp4: false
    enp6s0:
      dhcp4: false

  bonds:
    bond0:
      interfaces:
        - enp5s0
        - enp6s0
      parameters:
        mode: 802.3ad
        lacp-rate: fast
        mii-monitor-interval: 100
        transmit-hash-policy: layer3+4

  vlans:
    bond0.10:
      id: 10
      link: bond0
    bond0.20:
      id: 20
      link: bond0

  bridges:
    br-mgmt:
      interfaces:
        - bond0.10
      addresses:
        - 192.168.10.100/24
      routes:
        - to: default
          via: 192.168.10.1

    br-vms:
      interfaces:
        - bond0.20
      addresses:
        - 192.168.20.1/24

Verifying Bond Status¶

# Check bond status
cat /proc/net/bonding/bond0

# networkctl status
networkctl status bond0

# ip link
ip link show bond0
ip link show enp5s0
ip link show enp6s0

# Check LACP
cat /proc/net/bonding/bond0 | grep -A5 "802.3ad"

Example Bond Status¶

Ethernet Channel Bonding Driver: v5.x

Bonding Mode: IEEE 802.3ad Dynamic link aggregation
Transmit Hash Policy: layer3+4 (1)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0

802.3ad info
LACP rate: fast
Min links: 0
Aggregator selection policy (ad_select): stable
System priority: 65535

Slave Interface: enp5s0
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Aggregator ID: 1

Slave Interface: enp6s0
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Aggregator ID: 1

Troubleshooting¶

Bond Not Forming¶

# Check interfaces exist
ip link show

# Check interfaces aren't in use
ip addr show enp5s0
# Should show no IP

# Check kernel module
lsmod | grep bonding

LACP Not Negotiating¶

# Check LACP status
cat /proc/net/bonding/bond0 | grep -A10 "802.3ad"

# Verify switch config
# - Port-channel/LAG configured
# - Same LACP mode (active/passive)
# - Same speed on all ports

Failover Not Working¶

# Test failover
# Physically disconnect one cable

# Watch bond status
watch cat /proc/net/bonding/bond0

# Check MII status
ip link show enp5s0

Performance Issues¶

# Check hash policy
cat /proc/net/bonding/bond0 | grep "Transmit Hash"

# Monitor traffic distribution
# (Requires iftop or similar)
iftop -i bond0

Switch Configuration Reference¶

Cisco IOS LACP¶

interface range GigabitEthernet0/1-2
  channel-group 1 mode active
  channel-protocol lacp

interface Port-channel1
  switchport mode trunk

Juniper LACP¶

set interfaces ae0 aggregated-ether-options lacp active
set interfaces ge-0/0/0 ether-options 802.3ad ae0
set interfaces ge-0/0/1 ether-options 802.3ad ae0

Linux Bridge (No Config Needed for balance-alb)¶

For balance-alb mode, no switch configuration needed.