Reference Guide
454 | Link Aggregation Control Protocol (LACP)
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Important Points to Remember
• LACP enables you to add members to a port channel (LAG) as long as it has no static members.
Conversely, if the LAG already contains a statically defined member (
channel-member command),
the
port-channel mode command is not permitted.
• A static LAG cannot be created if a dynamic LAG using the selected number already exists.
• No dual membership in static and dynamic LAGs:
• If a physical interface is a part of a static LAG, then the command
port-channel-protocol lacp will
be rejected on that interface.
• If a physical interface is a part of a dynamic LAG, it cannot be added as a member of a static LAG.
The command
channel-member gigabitethernet x/y will be rejected in the static LAG interface
for that physical interface.
• A dynamic LAG can be created with any type of configuration.
• There is a difference between the
shutdown and no interface port-channel:
—The
shutdown command on LAG “xyz” disables the LAG and retains the user
commands. However, the system does not allow the channel number “xyz” to be statically
created.
— The command
no interface port-channel channel-number deletes the specified LAG,
including a dynamically created LAG. This command causes all LACP-specific
commands on the member interfaces to be removed. The interfaces are restored to a state
that is ready to be configured.
Note: There will be no configuration on the interface since that condition is required for an
interface to be part of a LAG
.
• Link dampening can be configured on individual members of a LAG. See Link Debounce Timer on
page 360 for more information.
LACP modes
FTOS provides the following three modes for configuration of LACP:
• Off—In this state, an interface is not capable of being part of a dynamic LAG. LACP does not run on
any port that is configured to be in this state.
• Active—In this state, the interface is said to be in the “active negotiating state.” LACP runs on any
link that is configured to be in this state. A port in Active state also automatically initiates negotiations
with other ports by initiating LACP packets.
• Passive—In this state, the interface is not in an active negotiating state, but LACP will run on the link.
A port in Passive state also responds to negotiation requests (from ports in Active state). Ports in
Passive state respond to LACP packets.
FTOS supports LAGs in the following cases:
• A port in Active state can set up a port channel (LAG) with another port in Active state.
• A port in Active state can set up a LAG with another port in Passive state.
A port in Passive state cannot set up a LAG with another port in Passive state.