How Dynamic Link Aggregation Works - HP FlexFabric 12900 Series Configuration Manual

other member ports. In this way, the two systems reach an agreement on which ports are placed in the
Selected state.
LACP functions
LACP offers basic LACP functions and extended LACP functions, as described in
Table 3 Basic and extended LACP functions
Category
Basic LACP functions
Extended LACP
functions
LACP priorities
LACP priorities include system LACP priority and port priority, as described in
priority value, the higher the priority.
Table 4 LACP priorities
Type
System LACP priority
Port priority
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 does not receive LACPDUs from the peer within the LACP timeout interval, the
member port considers the peer as failed.
The LACP timeout interval also determines the LACPDU sending rate of the peer. You can configure the
LACP timeout interval as the short timeout interval (3 seconds) or the long timeout interval (90 seconds).
If you configure the short timeout interval, the peer sends LACPDUs fast (one LACPDU per second). If you
configure the long timeout interval, the peer sends LACPDUs slowly (one LACPDU every 30 seconds).

How dynamic link aggregation works

Choosing a reference port
The system chooses a reference port from the member ports that are in up state and have the same
attribute configurations as the aggregate interface. A Selected port must have the same operational key
and attribute configurations as the reference port.
Description
Implemented through the basic LACPDU fields, including the system LACP priority,
system MAC address, port priority, port number, and operational key.
Implemented by extending the LACPDU with new TLV fields. This is how the LACP
MAD mechanism of the IRF feature is implemented. it can participate in LACP MAD
as either an IRF member device or an intermediate device.
For more information about IRF and the LACP MAD mechanism, see IRF
Configuration Guide.
Description
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. The system that has lower priority sets port
state accordingly.
Determines the likelihood of a member port to be selected on a system. The higher port
priority, the higher the likelihood of selection.
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Table 3.
Table 4. The smaller the