Both the LSP ping functionality and the remote ping functionality are available in MPLS Manager. A successful remote ping means that the routing-protocol sessions are operational between the source and destination devices, but does not necessarily mean that the Label Distribution Protocol sessions are operational between the devices. LDP is an MPLS signaling protocol for constructing LSPs.

If problems exist in LDP, routes can still exist, but the binding of those routes to labels might fail. The blocking of TCP port 646, which is the default port for LDP sessions, is an example of an LDP-problem environment in which routes still exist.

LSP ping identifies LDP failures and misconfigurations for LDP LSPs, commonly known as generic LSPs. In addition, MPLS Manager is able to discover and monitor non-targeted LDP sessions, as explained in “LdpAdjacency (non-targeted)” on page 50.