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Figure 5 Setting the aggregation state of a member port in a static aggregation group
2.
Aggregating links in dynamic mode
Dynamic aggregation is implemented through IEEE 802.3ad Link Aggregation Control Protocol
(LACP).
LACP uses LACPDUs to exchange aggregation information between LACP-enabled devices.
Each member port in an LACP-enabled aggregation group exchanges information with its peer.
When a member port receives an LACPDU, it compares the received information with
information received on the other member ports. In this way, the two systems reach an
agreement on which ports are placed in the Selected state.
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 peer system (the partner) negotiate a reference port by
using the following workflow:
a.
The two systems compare their system IDs to determine the system with the smaller system
ID.
A system ID contains the system LACP priority and the system MAC address.
−
The two systems compare their LACP priority values.
The lower the LACP priority, the smaller the system ID. If LACP priority values are the
same, the two systems proceed to compare their MAC addresses.
−
The two systems compare their MAC addresses.
The lower the MAC address, the smaller the system ID.
