Reference Guide

546 | Link Aggregation Control Protocol (LACP)
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via R2, as shown. Traffic is equally distributed between LAGs 1 and 2. If LAG 1 fails, all traffic
from R1 to R4 flows across LAG 2 only. This condition over-subscribes the link, and packets are
dropped.
To avoid packet loss, traffic must be re-directed through the next lowest-cost link (R3 to R4).
FTOS has the ability to bring LAG 2 down in the event that LAG 1 fails, so that traffic can be
re-directed, as described. This is what is meant by Shared LAG State Tracking. To achieve this
functionality, you must group LAG 1 and LAG 2 into a single entity, called a failover group.
Configure Shared LAG State Tracking
To configure Shared LAG State Tracking, you configure a failover group :
In the following example, LAGs 1 and 2 have been placed into to the same failover group.
R2#config
R2(conf)#port-channel failover-group
R2(conf-po-failover-grp)#group 1 port-channel 1 port-channel 2
View the failover group configuration using the show running-configuration po-failover-group
command, as shown in the example below.
Note: If a LAG interface is part of a redundant pair, it cannot be used as a member of a failover group
created for Shared LAG State Tracking.
Step Task Command Command Mode
1
Enter port-channel failover group mode. port-channel
failover-group
CONFIGURATION
2
Create a failover group and specify the
two port-channels that will be members
of the group.
group number port-channel
number port-channel
number
CONFIG-PO-FAILOVER-GRP
Po 1
Po 2
fnC0049mp
R1
R2 R3
R4
Po 1 failure
Po 2 over-subscribed