LAG Virtual Interface

The LAG virtual interface is a logical interface that represents a bundle of physical interfaces that form a LAG. The primary port that anchored the LAG no longer exists beginning with FastIron 08.0.61. Instead, all features running over a LAG will be anchored on the LAG virtual interface. All member ports of the LAG are treated as secondary ports and therefore, any physical port can be added or removed from the LAG without tearing down the LAG. The LAG virtual interface is created when a LAG is configured.

The LAG can be added, modified, or deleted using the respective commands in the LAG virtual interface mode. The LAG virtual interface and the properties it supports are similar to an Ethernet interface. The configuration of the LAGs using the LAG virtual interface is described in Creating a Link Aggregation Group (LAG). Like Ethernet interfaces, the LAG virtual interface also supports multi-interface mode.

Any new configuration or changes made to the LAG virtual interface are propagated to all ports in the LAG, ensuring a consistent configuration of the member ports. Interface-level configurations can be applied only on the LAG virtual interface and not on any member ports. If the member ports are mentioned in the interface command, it automatically moves to the LAG virtual interface mode in which that port is a member.

Note: LAG virtual interface is applicable only for static LAGs and dynamic LAGs and is not supported for keep-alive LAGs. LAG virtual interface configuration commands are not allowed for the SPX LAG virtual interface.

LAG virtual interface is displayed among the list of interfaces in various show commands.

To view the LAG virtual interface details, refer toDisplaying LAG information.

LAG MAC address

The Layer 2 protocols (xSTP and MRP) running over the LAG use the LAG MAC address as the source MAC address. The first physical port that is being added to the LAG becomes the MAC provider for the LAG virtual interface. When the first physical port (MAC provider) moves out, the next port is chosen as the MAC provider. However, a constant MAC address can be assigned to the LAG virtual interface using the lag-mac command.
Note: If VE or Layer 3 is configured on the LAG, the show interface brief command output displays the stack-mac as the LAG virtual interface MAC address.