RSVP-TE Self Ping

RSVP-TE label-switched paths (LSPs) might need to establish a new LSP instance and transfer traffic from an old LSP instance onto the new LSP instance before tearing down the old one. This type of configuration is referred to as a make-before-break (MBB) configuration. Traditionally, the Juniper devices have relied on configuring the following timer values for RSVP-TE to achieve a hitless (no traffic loss) MBB switchover: * optimize-switchover-delay-Amount of time to wait before switching to the new LSP instance. * optimize-hold-dead-delay-Amount of time to wait after switchover and before deletion of the old LSP instance. However, relying on the arbitrary time intervals might lead to undesirable results. For example, it might happen that the configured hold time was not enough for a new LSP to be set up, leading to traffic loss as the old LSP is torn down. As part of the RSVP-TE improvements, MPLS-OAM (LSP ping) is used, which confirms that the LSP data plane is established end-to-end. To address scale, the LSP Ping is routed through the data plane only, without involving the control plane.