When certain RSVP-TE optimizations are implemented, ingress LSRs can
receive RSVP RESV messages before forwarding state has been installed
on all downstream nodes. According to the RSVP-TE specification, the
ingress LSR can forward traffic through an LSP as soon as it receives
a RESV message. However, if the ingress LSR forwards traffic through
the LSP before forwarding state has been installed on all downstream
nodes, traffic can be lost. This memo describes LSP Self-ping. When
an ingress LSR receives an RESV message, it can invoke LSP Self-ping
procedures to ensure that forwarding state has been installed on all
downstream nodes. LSP Self-ping is an extremely light-weight
mechanism. It does not consume control plane resources on transit or
egress LSRs.