IS-IS SR-TE LDP Stitching

In an LDP network with gradual deployment of segment routing, there can be islands of devices that support either only LDP or only segment routing. This feature introduces support for LDP-to-segment routing and segment routing-to-LDP label switched path (LSP) stitching on the border router interconnecting LDP and segment routing domains. Thus, a packet arriving over an LDP-based LSP from an LDP domain can be forwarded over a segment routing-based LSP into a segment routing domain, and traffic arriving over a segment routing-based LSP from a segment routing domain can be forwarded over an LDP-based LSP into an LDP domain.