# SR/LDP Design Challenge #1

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An operator wants to build their network so that the core uses SR-only, and the edges use LDP-only. The edges are running on older hardware that does not support SR. Is an SRMS needed in this case?

## Answer <a href="#id-8892946e-5b17-4ec1-86f2-053c7b7151ad" id="id-8892946e-5b17-4ec1-86f2-053c7b7151ad"></a>

Yes, an SRMS mapping server is needed within the SR-only domain. An LSP that has a destination of an LDP-only node must have an SR prefix SID within the SR-only domain. So the SRMS will advertise mappings for all LDP-only nodes.
