Network interface bonding in Linux aggregates multiple physical network interfaces into a single logical interface too enhance bandwidth, load balancing, and redundancy. This technique is essential in complex network environments for improving performance and availability.

Linux supports several bonding modes, each with distinct characteristics and use cases.

Alias	Configuration Name	English Name	Chinese Name	Description
bond0	balance-rr	Round-robin policy	平衡轮询策略	Transmits packets sequentially across interfaces, providing load balancing and fault tolerance.
bond1	active-backup	Active-backup policy	活动备份策略	Only one interface is active; if it fails, a backup takes over, offering fault tolerance. MAC address is externally visible.
bond2	balance-xor	XOR policy	平衡策略	Selects transmission interface based on (source MAC XOR destination MAC) mod device count, providing load balancing and fault tolerance.
bond3	broadcast	Broadcast policy	广播策略	Sends all packets to every interface, ensuring fault tolerance.
bond4	802.3ad	IEEE 802.3ad Dynamic link aggregation	IEEE 802.3ad 动态链接聚合	Creates an aggregation group with shared speed and duplex settings, requiring switch support for 802.3ad mode and driver-based speed/duplex retrieval.
bond5	balance-tlb	Adaptive transmit load balancing	适配器传输负载均衡	Distributes outgoing traffic based on current load without special switch support; incoming traffic is handled by the current active interface.
bond6	balance-alb	Adaptive load balancing	适配器负载均衡	Includes mode5 features with ARP negotiation for receive load balancing, intercepting ARP requests to use hardware addresses from slave devices.

• Modes 0, 2, and 3 typically require static aggregation methods.
• Modes 1, 5, and 6 do not need switch configuration; network cards can aggregate automatically.
• Mode 4 requires 802.3ad support and switch configuration.

Active-Backup Mode

In this mode, only one network interface is active, with others as backups. If the active interface fails, a backup takes over, making it suitable for high-availability network connections.

Balance-RR (Round Robin) Mode

Packets are distributed in a round-robin fashion across all available interfaces. This mode provides load balancing but may not fully utilize bandwidth.

802.3ad (LACP) Mode

Utilizes the Link Aggregation Control Protocol (LACP) to bind multiple interfaces together, offering load balancing and redundancy. Switch support is required.

Balance-TLB (Transmit Load Balancing) Mode

Distributes packets based on current network traffic conditions, providing adaptive load balancing.

Balance-ALB (Adaptive Load Balancing) Mode

Learns optimal paths for packet transmission, suitable for dynamic network environments.

Configuration Steps on Linux Systems

Step 1: Install the ifenslave Tool

sudo apt-get install ifenslave

Step 2: Edit Network Configuration File

Modify the /etc/network/interfaces file to add bonding configurations:

# Network interfaces configuration
source /etc/network/interfaces.d/*

# Loopback interface
auto lo
iface lo inet loopback

# First slave interface
auto eth0
iface eth0 inet manual
    bond-master bond0

# Second slave interface
auto eth1
iface eth1 inet manual
    bond-master bond0

# Bonding interface
auto bond0
iface bond0 inet static
    address 192.168.1.100
    netmask 255.255.255.0
    gateway 192.168.1.1
    dns-nameservers 8.8.8.8 8.8.4.4
    slaves eth0 eth1
    bond-mode 1
    bond-miimon 100
    bond-lacp-rate 1

Step 3: Restart Network Services

sudo service networking restart

Configuration Steps on OpenWrt Systems

Check if necessary kernel components are installed:

opkg list | grep kmod-bonding

If not present, install kmod-bonding. In the latest official kernel version 5.15.162, this component is included by default. Older versions may require upgrading.

View current kernel version:

uname -r

Install link aggregation kernel module and LuCI graphical plugin:

opkg update
opkg install kmod-bonding
opkg install luci-proto-bonding

Offline installation using IPK packages:

• kmod-bonding: https://downloads.openwrt.org/releases/23.05.4/targets/x86/64/packages/kmod-bonding_5.15.162-1_x86_64.ipk
• luci-proto-bonding: https://downloads.openwrt.org/releases/23.05.4/packages/x86_64/luci/luci-proto-bonding_git-24.364.71483-75d2b84_all.ipk

After installation, reboot the system. The link aggregation feature will appear in the network interface configuration.