Q: 2
DRAG DROP Drag and drop the descriptions from the left onto the corresponding MPLS components on the right. 
Drag & Drop
Discussion
Maps look like this: LSR is the core/P router, FEC is for grouping traffic with same path/label, LER sits at the edge (PE), LDP handles label mapping between routers, and LSP defines the path across MPLS. Pretty sure that's right but let me know if I missed something subtle.
LSR to core routers, FEC for same path/label, LER to PE, LDP for label mapping, LSP is the path.
LSR → routers in the core (P routers), FEC → all traffic on same path/label, LER → routers connecting to customer (PE), LDP → exchanging label mapping info, LSP → path through MPLS. If the question had labeled a device as CE instead of PE, LER wouldn’t be the answer for that one. Came across this edge-case in another practice set.
FEC → all traffic to be forwarded using the same path and same label, LSP → path along which traffic flows across MPLS network, LER → routers that connect to the customer routers (PE routers), LSR → routers in the core (P routers), LDP → used for exchanging label mapping. Saw a similar question on a practice exam. Could be mixed up with LER/LSR if not careful.
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