Link aggregation and LACP configuration
Ethernet link aggregation, or simply link aggregation, combines multiple physical Ethernet ports into one logical link, called an aggregate link. Link aggregation delivers the following benefits:
∙Increases bandwidth beyond the limits of any single link. In an aggregate link, traffic is distributed across the member ports.
∙Improves link reliability. The member ports dynamically back up one another. When a member port fails, its traffic is automatically switched to other member ports.
Basic concepts
Aggregate interface
An aggregate interface is a logical Layer 2 or Layer 3 aggregate interface.
NOTE:
The device supports Layer 2 aggregation interfaces only.
Aggregation group
An aggregation group is a group of Ethernet interfaces combined together. When you create an aggregate interface, the device automatically creates an aggregation group of the same type and number as the aggregate interface. For example, when you create interface
You can assign Layer 2 Ethernet interfaces only to a Layer 2 aggregation group, and Layer 3 Ethernet interfaces only to a Layer 3 aggregation group.
NOTE:
The device supports Layer 2 aggregation groups only.
Aggregation states of member ports in an aggregation group
A member port in an aggregation group can be in either of the following aggregation states:
∙Selected: A Selected port can forward user traffic.
∙Unselected: An Unselected port cannot forward user traffic.
The rate of an aggregate interface is the sum of the selected member ports’ rates. The duplex mode of an aggregate interface is consistent with that of the selected member ports. All selected member ports use the same duplex mode.
For how the state of a member port is determined, see “Static aggregation mode” and “Dynamic aggregation mode”.
LACP
The IEEE 802.3ad Link Aggregation Control Protocol (LACP) enables dynamic aggregation of physical links. It uses link aggregation control protocol data units (LACPDUs) for exchanging aggregation information between
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