Indicating Load Balancing in Forwarding Tables

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The forwarding table designation used to indicate that load balancing is working correctly in Juniper Networks is "mlst," which stands for Multipath Load Sharing Table.

When load balancing is enabled on a Juniper device, multiple paths are available for forwarding packets to their destination. These paths may have different metrics, such as different link speeds or costs, which can affect the selection of the best path for each packet.

To implement load balancing, the device creates multiple forwarding table entries for each destination, each pointing to a different next-hop address or interface. These entries are stored in the Multipath Load Sharing Table (MLST), which is a separate table from the main unicast forwarding table (ucst).

When a packet arrives at the device, it is matched against the entries in the MLST. The device selects one of the entries using a load balancing algorithm, such as round-robin or least-fill. The selected entry determines the next-hop address or interface for the packet, and the packet is forwarded accordingly.

If load balancing is working correctly, the MLST should contain multiple entries for each destination, and packets should be distributed across these entries using the load balancing algorithm. The "mlst" designation in the output of the "show route" command indicates that load balancing is enabled and working correctly for the specified destination.

The other answer choices in the question ("ucst," "msct," and "ulst") are not valid forwarding table designations in Juniper Networks and are not related to load balancing.