Cisco 500 series Administration Manual page 155

Port Management
Configuring Link Aggregation
NOTE
STEP 1
STEP 2
STEP 3
STEP 4
Cisco 500 Series Stackable Managed Switch Administration Guide
The following algorithm is used to determine whether LACP port priorities are
taken from the local or remote device: the local LACP System Priority is compared
to the remote LACP System Priority. The device with the lowest priority controls
candidate port selection to the LAG. If both priorities are the same, the local and
remote MAC addresses are compared. The priority of the device with the lowest
MAC address controls candidate port selection to the LAG.
A dynamic LAG can have up to 16 Ethernet ports of the same type. Up to eight
ports can be active, and up to eight ports can be in standby mode. When there are
more than eight ports in the dynamic LAG, the switch on the controlling end of the
link uses port priorities to determine which ports are bundled into the LAG and
which ports are put in hot-standby mode. Port priorities on the other switch (the
non-controlling end of the link) are ignored.
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.
Setting Port LACP Parameter Settings
The LACP page displays and enables configuration of the LACP System Priority,
LACP timeout, and LACP port priority. LACP timeout is a per port parameter, and is
the time interval between the sending and receiving of consecutive LACP PDUs.
With all factors equal, when the LAG is configured with more candidate ports than
the maximum number of active ports allowed, the switch selects ports as active
from the dynamic LAG that has the highest priority
The LACP setting is irrelevant on ports that are not members of a dynamic LAG.
To define the LACP settings:
Click Port Management > Link Aggregation > LACP. The
Enter the LACP System Priority. See
Select a port, and click Edit. The
Enter the values for the following fields:
Configuring LACP.
Edit LACP page opens.
10
LACP
page opens.
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