Port Management
Link Aggregation
Cisco Sx350, SG350X, SG350XG, Sx550X & SG550XG Series Managed Switches, Firmware Release 2.2.5.x 154
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The following are additional rules used to select the active or standby ports in a dynamic
LACP:
• Any link operating at a different speed from the highest-speed active member or
operating at half-duplex is made standby. All the active ports in a dynamic LAG
operate at the same baud rate.
• If the port LACP priority of the link is lower than that of the currently-active link
members, and the number of active members is already at the maximum number, the
link is made inactive, and placed in standby mode.
LACP With No Link Partner
In order for LACP to create a LAG, the ports on both link ends should be configured for
LACP, meaning that the ports send LACP PDUs and handle received PDUs.
However, there are cases when one link partner is temporarily not configured for LACP. One
example for such case is when the link partner is on a device, which is in the process of
receiving its configuration using the auto-config protocol. This device's ports are not yet
configured to LACP. If the LAG link cannot come up, the device cannot ever become
configured. A similar case occurs with dual-NIC network-boot computers (e.g. PXE), which
receive their LAG configuration only after they bootup.
When several LACP-configured ports are configured, and the link comes up in one or more
ports but there are no LACP responses from the link partner for those ports, the first port that
had link up is added to the LACP LAG and becomes active (the other ports become non-
candidates). In this way, the neighbor device can, for example, get its IP Address using DHCP
and get its configuration using auto-configuration.
LACP Settings
Use the LACP page to configure the candidate ports for the LAG and to configure the LACP
parameters per port.
With all factors equal, when the LAG is configured with more candidate ports than the
maximum number of active ports allowed (8), the device selects ports as active from the
dynamic LAG on the device that has the highest priority.
NOTE The LACP setting is irrelevant on ports that are not members of a dynamic LAG.
To define the LACP settings:
STEP 1 Click Port Management > Link Aggregation > LACP.
STEP 2 Enter the LACP System Priority.
STEP 3 Select a port, and click Edit.
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