Segment Routing MPLS (SR-MPLS)
The introduction of SR in an MPLS network does not require any changes to the underlying MPLS data plane or hardware forwarding capabilities.
In MPLS networks, routers use label-switching to forward packets based on pre-established Label Switched Paths (LSPs). These labels are assigned by a control plane protocol such as Label Distribution Protocol (LDP) or Resource Reservation Protocol with Traffic Engineering (RSVP-TE).
When SR is introduced, the source node determines and sets the entire path of a packet, from its origin to the final destination, including all the intermediate hops, using a segment or list of segments. But it doesn’t replace the label-switching mechanism; instead, it uses the existing MPLS data plane and forwarding infrastructure to implement segment-based forwarding.
With SR-MPLS, the difference lies in how the labels are assigned, distributed, and utilized. The SR information is encoded as MPLS labels, and each label...