F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices High Availability Configuration Guide-6PW100

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8BConfiguring Ethernet link aggregation
48B
Overview
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.
As shown in
569HFigure 64, Device A and Device B are connected by three physical Ethernet links. These
physical Ethernet links are combined into an aggregate link, Link Aggregation 1. The bandwidth of this
aggregate link is as high as the total bandwidth of the three physical Ethernet links. At the same time, the
three Ethernet links back up one another.
Figure 64 Ethernet link aggregation
170BBasic concepts
This section describes some basic link aggregation concepts.
338BAggregation group, member port, and aggregate interface
Link aggregation is implemented by combining Ethernet interfaces into a link aggregation group. Each
link aggregation group has one logical aggregate interface. To an upper layer entity, a link aggregation
group appears to be a single logical link and data traffic is transmitted through the aggregate interface.
The rate of an aggregate interface equals the total rate of its member ports in Selected state, and its
duplex mode is the same as the selected member ports. For more information about the states of member
ports in an aggregation group, see "
570HAggregation states of member ports in an aggregation group."
Aggregate interfaces are one of the following types:
• Layer 2 aggregate interfaces—Only Layer 2 aggregate interfaces/aggregation groups can be
configured in the Web interface.
• Layer 3 aggregate interfaces—On a Layer 3 aggregate interface, you can create subinterfaces.
The Layer 3 aggregate subinterfaces are logical interfaces operating at the network layer. They can
receive VLAN tagged packets for their Layer 3 aggregate interface.
When you create an aggregate interface, the firewall automatically creates an aggregation group of the
same type and number as the aggregate interface. For example, when you create interface
Bridge-Aggregation 1, Layer 2 aggregation group 1 is automatically created.
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.