H3C Technologies H3C S7500E Series Switches - Manual (Page 126)

11-2
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 aggregated together. 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 looks like a single logical link and data traffic is transmitted through the aggregate
interface.
There are two types of aggregate interfaces: bridge-aggregation (BAGG) interfaces, which are Layer 2
aggregate interfaces, and route-aggregation (RAGG) interfaces, which are Layer 3 aggregate
interfaces. When an aggregate interface is created, an aggregation group of the same type and
numbered the same is created automatically. For example, when you create interface
Bridge-aggregation 1, Layer 2 aggregation group 1 is created.
To a Layer 2 aggregation group, you can assign only Layer 2 Ethernet interfaces.
Current device only supports Layer 2 aggregation group and Layer 2 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 that of the selected member ports. For more information about the
states of member ports in an aggregation group, refer to
Aggregation states of member ports in an
aggregation group .
Aggregation states of member ports in an aggregation group
A member port in an aggregation group can be in either of the following two aggregation states:
Selected: a selected port can forward user traffic.
Unselected: an unselected port cannot forward user traffic.
Operational key
When aggregating ports, the system automatically assigns each port an operational key based on port
information such as port rate and duplex mode. Any change to this information triggers a recalculation
of this operational key. The operational key of a port indicates the aggregation capability of the port.
In an aggregation group, all selected member ports are assigned the same operational key.
Configuration classes
Every configuration setting on a member port in a link aggregation group may affect the aggregation
state of the port in the group more or less. They are divided into three configuration classes:
Port attribute configurations, including port rate, duplex mode, and link status (up/down), which
are the most basic port configurations.
Class-two configurations, as described in Table 11-1 . A member port can be placed in selected
state only if it has the same class-two configurations as the aggregate interface.