MPLS to SR Migration Planner
Moving from LDP to segment routing happens one router at a time. This shows whether transport still works at each stage, and where it does not.
Local toolYour network plan stays in your browser. Nothing you enter is uploaded, logged, or sent to any server.
Routers along the path
Does transport survive?
The order that works, and the one that does not
LDP and segment routing distribute labels differently, and a router speaking only one cannot exchange labels with a router speaking only the other. Migration therefore has an order.
Stage one: enable SR everywhere, alongside LDP. Every router runs both. LDP continues to carry traffic, SR is present and idle. Nothing changes for the data plane, which is the point — this stage should be invisible.
Stage two: prefer SR. Where both protocols offer a label for the same destination, one wins by preference. Shifting that preference moves traffic onto SR while LDP is still there to fall back to.
Stage three: remove LDP, once nothing depends on it.
The mistake is removing LDP from a router in the middle before its neighbours run SR. Two adjacent routers then share no way to exchange labels, and transport breaks across that adjacency — which is exactly the check this tool performs. An island of SR-only routers surrounded by LDP-only ones does the same thing.
Where the two must meet, something has to stitch them. A router running both can map between LDP and SR so a path crossing the boundary still works. That capability is real and its details differ by platform, so it is worth confirming rather than assuming.
This is a design model. It reasons about which routers can exchange labels with which, not about your configuration, and every stage needs validating on the platforms involved.
Related tools
SRGB & Prefix-SID Planner for the label plan. Label Stack Visualizer for what the packets look like.