H3C Technologies H3C S5560 Series Switches - Manual (Page 61)

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