8.3.3.8 - Force10 Networks

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To debug LACP, use the following command:
Command Syntax Command Mode Purpose
[no] debug lacp [config | events | pdu
[in | out | [interface [in | out]]]]
Shared LAG State Tracking
Shared LAG State Tracking provides the flexibility to bring down a port channel (LAG) based on the
operational state of another LAG. At any time, only two LAGs can be a part of a group such that the fate
(status) of one LAG depends on the other LAG.
In Figure 19-5, line-rate traffic from R1 destined for R4 follows the lowest-cost route 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.
Figure 19-5. LAGs using ECMP without Shared LAG State Tracking
R4
R1
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:
394 | Link Aggregation Control Protocol
Po 1 failure
EXEC Debug LACP, including configuration and events.
Po 1
Step Task Command Command Mode
1 Enter port-channel failover group mode. port-channel failover-group CONFIGURATION
Po 2
Po 2 over-subscribed
R2 R3
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