How Dynamic Link Aggregation Works - HP 6125XLG Configuration Manual

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 the LACP timeout interval, the
member port considers the peer failed.
The LACP timeout interval also determines the LACPDU sending rate of the peer. LACP timeout intervals
include the following types:
Short timeout interval—3 seconds. If you use the short timeout interval, the peer sends one LACPDU
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per second.
Long timeout interval—90 seconds. If you use the long timeout interval, the peer sends one
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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.
The local system (the actor) and the remote system (the partner) negotiate a reference port by using the
following workflow:
1. The systems compare their system IDs. (A system ID contains the system LACP priority and the
system MAC address.) The lower the LACP priority, the smaller the system ID. If LACP priority
values are the same, the two systems compare their MAC addresses. The lower the MAC address,
the smaller the system ID.
2. The system with the smaller system ID chooses the port with the smallest port ID as the reference
port. (A port ID contains a port priority and a port number.) The port with the lower priority value
is chosen. If two ports have the same aggregation priority, the system compares their port numbers.
The port with the smaller port number and the same attribute configurations as the aggregate
interface becomes the reference port.
Setting the aggregation state of each member port
After the reference port is chosen, the system with the lower system ID sets the state of each member port
on its side.
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