Operation Manual – Link AggregationH3C S3100 Series Ethernet Switches Chapter 1 Link Aggregation Configuration1-1Chapter 1 Link Aggregation Configuration1.1 Overview1.1.1 Introduction to Link AggregationLink aggregation can aggregate multiple Ethernet ports together to form a logicalaggregation group. To upper layer entities, all the physical links in an aggregation groupare a single logical link.Link aggregation is designed to increase bandwidth by implementingoutgoing/incoming load sharing among the member ports in an aggregation group. Linkaggregation group also allows for port redundancy, which improves connectionreliability.1.1.2 Introduction to LACPLink aggregation control protocol (LACP) is designed to implement dynamic linkaggregation and deaggregation. This protocol is based on IEEE802.3ad and uses linkaggregation control protocol data units (LACPDUs) to interact with its peer.With LACP enabled on a port, LACP notifies the following information of the port to itspeer by sending LACPDUs: priority and MAC address of this system, priority, numberand operation key of the port. Upon receiving the information, the peer compares theinformation with the information of other ports on the peer device to determine the portsthat can be aggregated. In this way, the two parties can reach an agreement inadding/removing the port to/from a dynamic aggregation group.Operation key is generated by the system. It is determined by port settings such as portspeed, duplex mode, and basic configurations (refer to Requirements on Ports for LinkAggregation for description on basic configurations).z Selected ports in a manual aggregation group or a static aggregation group havethe same operation key.z Member ports in a dynamic aggregation group have the same operation key.1.1.3 Requirements on Ports for Link AggregationTo achieve outgoing/incoming load sharing in an aggregation group, the member portsto perform load balancing must have the same speed, duplex mode, and basicconfigurations, which include:z STP configuration, including STP status (enabled or disabled), link attribute(point-to-point or not), STP priority, STP path cost, STP packet format, loop guardstatus, root guard status, edge port or not.
