Port Management
Link Aggregation
Cisco 350XG & 550XG Series 10G Stackable Managed Switches
174
10
•
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.
STEP 4
Enter the values for the following fields:
