Which LSPs are established in Downstream Unsolicited (DU) label advertisement mode?

In the context of label-switched paths (LSPs) established in the Downstream Unsolicited (DU) label advertisement mode, all the listed activities play a significant role in the label distribution process.

When LSPs are set up in the DU mode, the Label Distribution Protocol (LDP) allows for the distribution of labels from the downstream router to the upstream routers without requiring any specific request for labels for each destination. First, binding a Forwarding Equivalence Class (FEC) to a label is essential because it is the fundamental action that matches a particular data stream (the FEC) to a specific label, which directs the packet forwarding process through an MPLS network.

Next, not creating a new FEC for a new destination illustrates the efficiency inherent in the DU mode. Since routers propagate labels for FECs that they already know, this approach ensures that labels can be reused where appropriate, simplifying the routing and reducing overhead.

Lastly, allocating labels for the FEC is a critical part of the label distribution, facilitating IP packets to be switched at high speeds based on the labels rather than processing the entire IP address. This label allocation ensures that any data packet that falls into the bound FEC can be effectively managed