Before implementing LDP, familiarize yourself with the following key terms and definitions.
| Apply Current Route | Compare the current route with the received label mappings and install any downstream mappings, as appropriate. |
| Current Route | Current next hop info for a FEC. The current route may not be applied immediately to the current label mapping as a result of LWD at ingress. |
| Downstream mapping (DM) | Represents the label mapping received from a downstream peer for a FEC. |
| FEC | Forwarding Equivalency Class. Each FEC is a destination IP address for an LDP tunnel. |
| LDP | Label Distribution Protocol. |
| Label mapping | LDP message that indicates the label to be used for an FEC from the peer. |
| LSP | Label Switched Path. |
| LWD | Label Withdrawal Delay. |
| Route event | Update from the routing table to LDP. |
| Upstream Mapping | Represents the label mapping sent to an upstream peer for a FEC. |