36The IEEE 802.3ad LACP offers basic LACP functions and extended LACP functions, as describedin Table 3.Table 3 Basic and extended LACP functionsCategory DescriptionBasic LACPfunctionsImplemented through the basic LACPDU fields, including the system LACP priority, systemMAC address, port aggregation priority, port number, and operational key.Each member port in a LACP-enabled aggregation group exchanges the precedinginformation with its peer. When a member port receives an LACPDU, it compares thereceived information with the information received on the other member ports. In this way,the two systems reach an agreement on which ports should be placed in the Selected state.Extended LACPfunctionsImplemented by extending the LACPDU with new Type/Length/Value (TLV) fields. This ishow the LACP multi-active detection (MAD) mechanism of the Intelligent Resilient Framework(IRF) feature is implemented. The S3600V2 Switch Series can participate in LACP MAD aseither an IRF member switch or an intermediate device.For more information about IRF, member switches, intermediate devices, and the LACP MAD mechanism,see IRF Configuration Guide.2. LACP prioritiesLACP priorities have the following types: system LACP priority and port aggregation priority.Table 4 LACP prioritiesType Description RemarksSystem LACPpriorityUsed by two peer devices (or systems) to determine which one issuperior in link aggregation.In dynamic link aggregation, the system that has higher system LACPpriority sets the Selected state of member ports on its side first, and thenthe system that has lower priority sets the port state accordingly.The smaller thepriority value,the higher thepriority.Port aggregationpriorityDetermines the likelihood of a member port to be selected on a system.The higher the port aggregation priority, the higher the likelihood.3. LACP timeout intervalThe LACP timeout interval specifies how long a member port waits to receive LACPDUs from thepeer port. If a local member port fails to receive LACPDUs from the peer within three times theLACP timeout interval, the member port assumes that the peer port has failed. You can configurethe LACP timeout interval as either the short timeout interval (1 second) or the long timeout interval(30 seconds).Link aggregation modesLink aggregation has the following modes: dynamic and static. Dynamic link aggregation uses LACPand static link aggregation does not. Table 5 compares the two aggregation modes.
