Shared Lag State Tracking; Configuring Shared Lag State Tracking - Dell C9000 Series Networking Configuration Manual

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.
As shown in the following illustration, the line-rate traffic from R1 destined for R4 follows the lowest-cost
route via R2. 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 60. Shared LAG State Tracking
To avoid packet loss, redirect traffic 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 traffic 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.

Configuring Shared LAG State Tracking

To configure shared LAG state tracking, you configure 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
Link Aggregation Control Protocol (LACP) 627