RSVP-TE Improvements

This feature introduces the following RSVP-TE improvements: * Ensuring LSP data-plane readiness before an LSP starts to carry traffic Make-before-break (MBB) configuration refers to a mechanism where 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. Traditionally, the implementation of RSVP-TE to achieve a hitless (no traffic loss) MBB switchover has relied on configuring the timer values in optimize-switchover-delay or optimize-hold-dead-delay. However, relying on the arbitrary time intervals might lead to undesirable results. For example, it might happen that 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. * LSP characteristic data visualization show mpls association: Display the MPLS LSPs based on the association with an incoming or outgoing LSP interface. The command output displays the list of RSVP-TE LSPs carrying traffic in to and out of the same interface. show mpls correlation label: Display the correlation information for the MPLS label-switched path (LSP) with the owner of the label. The command output displays the RSVP-TE LSP using the specified label.