Specifications

Chapter 6 Setting Network Preferences 73
To list devices that support VLANs:
$ networksetup -listdevicesthatsupportVLAN
IEEE 802.3ad Ethernet Link Aggregation
IEEE 802.3ad provides increased bandwidth and automatic failover for the server
environment.
Apple introduced the implementation of the IEEE 802.3ad Ethernet Link Aggregation
standard as part of the ifconfig tool. IEEE 802.3ad is a standard for bonding or
aggregating multiple Ethernet ports into one virtual interface.
The aggregated ports appear as a single IP address internally to your computer and
tools and externally to other clients on the Internet. Any tool or server that relies on
your IP address will continue to work seamlessly without modifications.
The advantage of aggregation is that the virtual interface provides increased
bandwidth by merging the bandwidth of individual ports. The TCP connection load is
then balanced across the ports.
In addition to load balancing, IEEE 802.3ad provides automatic failover in the event a
port or cable fails. Traffic that was routed over the failed port is rerouted to a remaining
port. This failover is transparent to the software using the connection.
Configuring a Network Interface
You can configure a network interface for TCP/IP using ifconfig. This tool is used to
bring the interface up or down and set the interface IP address and subnet mask.
To add an Ethernet interface to a bond virtual device (pseudo device):
$ ifconfig bond_interface_name bondev physical_interface
The bond_interface_name parameter is the name of the pseudo device and the
physical_interface parameter is the Ethernet interface you want to associate with the
pseudo device (for example, en0).
If this is the first physical interface to be associated with the bond interface, the bond
interface inherits the Ethernet address from the physical interface.
Physical interfaces that are added to the bond interface have their Ethernet address
reprogrammed so members of the bond have the same Ethernet address.
If the physical interface is subsequently removed from the bond, a new Ethernet
address is chosen from the remaining interfaces, and interfaces are reprogrammed with
the new Ethernet address. If no remaining interfaces exist, the bond interface’s Ethernet
address is cleared.