CR: Constraint-based routing.
FA: Forward Adjacency
FSC: Fiber switch capable
GMPLS: Generalized MPLS. A set of routing and signalling protocols for distributing topology information (routing) and provisioning and tearing down circuits (signalling).
LDP: Label Distribution Protocol. Signaling protocol in GMPLS. Currently abandoned in favour of RSVP-TE
LER: Label Edge Router. Mostly used in MPLS (not as much in GMPLS). Router or other device that is on the edge of a (G)MPLS domain.
LMP: Link Management Protocol. A protocol to manage links on the lowest layer (e.g. neighbour discovery, and fault isolation and signaling).
LSC: Lambda switch capable.
LSP: Label Switched Path. A GMPLS connection between two devices, on the same (OSI) layer. A LSP may be tunneled (multiplexed) through another LSP on a lower layer.
LSR: Label Switching Router. Device that is capable to understand MPLS or GMPLS. In MPLS, this is a router. In GMPLS, this can be any network device. So for GMPLS, the naming is odd, but it has stuck.
LSA: Link state advertisement. A message in a routing protocol
MPLS: Multiprotocol Label Switching. A protocol on which GMPLS is based.
OSPF: Open Shortest Path First. A routing protocol.
PSC: Packet switch capable
RSVP: Resource reSerVation Protocol. A signaling protocol.
SRLG: Shared Risk Link Group. A set of links in the same SRLG share a resource (e.g. a fiber conduit) whose failure will affect all links.
TE: Traffic Engineering
TLV: Type, Length and Value. A part of a protocol message.