Managing HP Serviceguard for Linux, Eighth Edition, March 2008

Understanding Serviceguard Software Components
How the Network Manager Works
Chapter 3 77
Bonding of LAN Interfaces
On the local node, several LAN interfaces can be grouped together in a
process known in Linux as channel bonding. In the bonded group, one
interface is used to transmit and receive data, while the others are
available as backups. If one interface fails, another interface in the
bonded group takes over. It is strongly recommended to use channel
bonding in each critical IP subnet to achieve highly available network
services.
Host Bus Adapters (HBAs) do not have to be identical. Ethernet LANs
must be the same type, but can be of different bandwidth (for example 1
Gb and 100 Mb). Serviceguard for Linux supports the use of bonding of
LAN interfaces at the driver level. The Ethernet driver is configured to
employ a group of interfaces.
Once bonding is enabled, each interface can be viewed as a single logical
link of multiple physical ports with only one IP and MAC address. There
is no limit to the number of slaves (ports) per bond, and the number of
bonds per system is limited to the number of Linux modules you can
load.
You can bond the ports within a multi-ported networking card (cards
with up to four ports are currently available). Alternatively, you can bond
ports from different cards. Figure 3-17 shows an example of four
separate interfaces bonded into one aggregate.
Figure 3-17 Bonded Network Interfaces
The LANs in the non-bonded configuration have four LAN cards, each
associated with a separate non-aggregated IP address and MAC address,
and each with its own LAN name (eth1, eth2, eth3, eth4). When these
ports are aggregated, all four ports are associated with a single IP