1-11 Link Aggregation Configurationz The term switch used throughout this chapter refers to a switching device in a generic sense or theswitching engine of a unified switch in the WX3000 series.z The sample output information in this manual was created on the WX3024. The output informationon your device may vary.OverviewIntroduction to Link AggregationLink aggregation means aggregating several ports together to form an aggregation group, so as toimplement outgoing/incoming load sharing among the member ports in the group and to enhance theconnection reliability.Depending on different aggregation modes, link aggregation falls into three types: manual, static LACP,and dynamic LACP aggregations. Depending on whether or not load sharing is implemented,aggregation groups can be load-sharing or non-load-sharing aggregation groups.For the member ports in an aggregation group, their basic configuration must be the same. The basicconfiguration includes STP, QoS, VLAN, port attributes and other associated settings.z STP configuration, including STP status (enabled or disabled), link attribute (point-to-point or not),STP priority, path cost, standard packet format, maximum packet transmission speed, loopprevention status, root protection status, edge port or not.z QoS configuration, including traffic limit, priority remarking, default 802.1p priority, bandwidthassurance, congestion avoidance, traffic redirection, traffic statistics, and so on.z VLAN configuration, including permitted VLANs, and default VLAN ID.z Port attribute configuration, including port rate, duplex mode, and link type (trunk, hybrid, oraccess).Introduction to LACPThe purpose of link aggregation control protocol (LACP) is to implement dynamic link aggregation anddeaggregation. This protocol is based on IEEE802.3ad and uses LACPDUs (link aggregation controlprotocol data unit) to interact with its peer.After LACP is enabled on a port, LACP notifies the following information of the port to its peer bysending LACPDUs: priority and MAC address of this system, priority, number and operation key of theport. Upon receiving the information, the peer compares the information with the information of otherports on the peer device to determine the ports that can be aggregated. In this way, the two parties canreach an agreement in adding/removing the port to/from a dynamic aggregation group.
