Configuring Ethernet Link-Aggregation; Basic Concepts - HP A5830 Configuration Manual

Configuring Ethernet link-aggregation

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 back up one another dynamically. When a member port

fails, its traffic is switched automatically to other member ports.
As shown in
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 4 Diagram for Ethernet link-aggregation
GE1/0/1
GE1/0/2
GE1/0/3
Device A

Basic concepts

Aggregation group, member port, aggregate interface
Link-aggregation is implemented through link-aggregation groups. An aggregation group is a group of
Ethernet interfaces combined together, which are called member ports of the aggregation group. For
each aggregation group, a logical interface, called an aggregate interface, is created. To an upper layer
entity that uses the link-aggregation service, a link-aggregation group appears to be a single logical link
and data traffic is transmitted through the aggregate interface.
When you create an aggregate interface, the switch 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 created.
Only assign Layer 2 Ethernet interfaces to a Layer 2 aggregation group.
The rate of an aggregate interface equals the total rate of its member ports in the 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
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.
Figure 4, Device A and Device B are connected by three physical Ethernet links. These
Link aggregation 1
―Aggregation states of member ports in an aggregation
GE1/0/1
GE1/0/2
GE1/0/3
Device B
26
group.‖