Multiple network interfaces may be bonded (“teamed”) together using lagg(4) for fault tolerance and/or increased bandwidth.
Creating/Editing a LAGG¶
LAGG interfaces are managed at Interfaces > (assign), on the LAGG tab.
When adding or editing a LAGG group, Ctrl-click to select the Parent interfaces to bond and then select a protocol. Several protocols are available and they are explained on the LAGG editing page. These descriptions have been reproduced in the next section.
A Description may also be entered for this LAGG group.
The most common protocol for use with LAGG is LACP. Using LACP also requires that the switch and ports to which these NICs connect be configured properly for LACP.
Sends and receives traffic only through the master port. If the master port becomes unavailable, the next active port is used. The first interface added is the master port; any interfaces added after that are used as failover devices.
Supports the IEEE 802.3ad Link Aggregation Control Protocol (LACP) and the Marker Protocol. LACP will negotiate a set of aggregable links with the peer in to one or more Link Aggregated Groups. Each LAG is composed of ports of the same speed, set to full-duplex operation. The traffic will be balanced across the ports in the LAG with the greatest total speed, in most cases there will only be one LAG which contains all ports. In the event of changes in physical connectivity, Link Aggregation will quickly converge to a new configuration.
Balances outgoing traffic across the active ports based on hashed protocol header information and accepts incoming traffic from any active port. This is a static setup and does not negotiate aggregation with the peer or exchange frames to monitor the link. The hash includes the Ethernet source and destination address, and, if available, the VLAN tag, and the IP source and destination address.
Distributes outgoing traffic using a round-robin scheduler through all active ports and accepts incoming traffic from any active port.
This protocol is intended to do nothing: it disables any traffic without disabling the lagg interface itself.
Usage with Multiple Switches¶
Some protocols such as LACP will only work across multiple switches if the switches are Stackable.
Using a LAGG does not necessarily guarantee full throughput equal to the sum of all interfaces. In particular, a single flow will not exceed the throughput of a LAGG member interface. Traffic on a LAGG is hashed in such a way that flows between two hosts, such as pfSense® software and an upstream gateway, would only use a single link since the flow is between a single MAC address on each side.
In networks where there are many hosts communicating with different MAC addresses, the usage can approach the sum of all interfaces in the LAGG.