1-11 Link Aggregation ConfigurationWhen configuring link aggregation, go to these sections for information you are interested in:z Overviewz Link Aggregation Classificationz Aggregation Group Categoriesz Link Aggregation Configurationz Displaying and Maintaining Link Aggregation Configurationz Link Aggregation Configuration ExampleOverviewIntroduction to Link AggregationLink aggregation aggregates multiple physical Ethernet ports into one logical link, also called anaggregation group.It allows you to increase bandwidth by distributing traffic across the member ports in the aggregationgroup. In addition, it provides reliable connectivity because these member ports can dynamically backup each other.Introduction to LACPThe Link Aggregation Control Protocol (LACP) is defined in IEEE 802.3ad. It uses link aggregationcontrol protocol data units (LACPDUs) for information exchange between LACP-enabled devices.With LACP enabled on a port, LACP notifies the following information of the port to its peer by sendingLACPDUs: priority and MAC address of this system, priority, number and operation key of the port.Upon receiving the information, the peer compares the information with the information of other ports onthe peer device to determine the ports that can be aggregated. In this way, the two parties can reach anagreement in adding/removing the port to/from a dynamic aggregation group.When aggregating ports, link aggregation control automatically assigns each port an operational keybased on the port speed, duplex mode, and basic configurations described in ConsistencyConsiderations for the Ports in Aggregation.In a manual or static link aggregation group, the selected ports are assigned the same operational key.In a dynamic link aggregation group, all member ports are assigned the same operational key.Consistency Considerations for the Ports in AggregationTo participate in traffic sharing, member ports in an aggregation group must use the sameconfigurations with respect to STP, QoS, GVRP, QinQ, BPDU tunnel, VLAN, port attributes, MACaddress learning, and so on as shown in the following table.
