HP 6125G HP 6125G & 6125G/XG Blade Switches Layer 2 - LAN Switching Co - Page 40

Table 3 Basic and extended LACP functions Category Basic LACP functions Extended LACP functions Description Implemented through the basic LACPDU fields, including the system LACP priority, system MAC address, port aggregation priority, port number, and operational key. Each member port in a LACP-enabled aggregation group exchanges the preceding information with its peer. When a member port receives an LACPDU, it compares the received 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. Implemented by extending the LACPDU with new Type/Length/Value (TLV) fields. This is how the LACP multi-active detection (MAD) mechanism of the Intelligent Resilient Framework (IRF) feature is implemented. The Switch Series can participate in LACP MAD as either 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 priorities LACP priorities have the following types: system LACP priority and port aggregation priority. Table 4 LACP priorities Type System LACP priority Port aggregation priority Description Remarks Used by two peer devices (or systems) to determine which one is superior in link aggregation. In dynamic link aggregation, the system that has higher system LACP priority sets the Selected state of member ports on its side first, and then the system that has lower priority sets the port state accordingly. Determines the likelihood of a member port to be selected on a system. The higher the port aggregation priority, the higher the likelihood. The smaller the priority value, the higher the priority. 3. LACP timeout interval The LACP timeout interval specifies how long a member port waits to receive LACPDUs from the peer port. If a local member port fails to receive LACPDUs from the peer within three times the LACP timeout interval, the member port assumes that the peer port has failed. You can configure the LACP timeout interval as either the short timeout interval (1 second) or the long timeout interval (30 seconds). Link aggregation modes Link aggregation has the following modes: dynamic and static. Dynamic link aggregation uses LACP and static link aggregation does not. Table 5 compares the two aggregation modes. Table 5 A comparison between static and dynamic aggregation modes Aggregation mode Static LACP status on member ports Pros Cons Disabled Aggregation is stable. Peers do not affect the aggregation state of the member ports. The member ports do not adjust the aggregation state according to that of the peer ports. The administrator must manually maintain link aggregations. 31