Administrator Guide

• Debug LACP, including conguration and events.

EXEC mode

Shared LAG State Tracking

Shared LAG state tracking provides the exibility 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.

As shown in the following illustration, the line-rate trac from R1 destined for R4 follows the lowest-cost route via R2. Trac is equally

distributed between LAGs 1 and 2. If LAG 1 fails, all trac from R1 to R4 ows across LAG 2 only. This condition over-subscribes the link

and packets are dropped.

Figure 62. Shared LAG State Tracking

To avoid packet loss, redirect trac through the next lowest-cost link (R3 to R4). the system has the ability to bring LAG 2 down if LAG 1

fails, so that trac can be redirected. This redirection 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.

Conguring Shared LAG State Tracking

To congure shared LAG state tracking, you congure a failover group.

NOTE

: If a LAG interface is part of a redundant pair, you cannot use it as a member of a failover group created for shared LAG

state tracking.

1 Enter port-channel failover group mode.

CONFIGURATION mode

port-channel failover-group

2 Create a failover group and specify the two port-channels that will be members of the group.

CONFIG-PO-FAILOVER-GRP mode

group number port-channel number port-channel number

Link Aggregation Control Protocol (LACP)

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