Label Information Base
Software table
Label Information Base (LIB) is the software table maintained by IP/MPLS capable routers to store the details of port and the corresponding MPLS router label to be popped/pushed on incoming/outgoing MPLS packets.
Entries are populated from label-distribution protocols.
LDP is a protocol that automatically generates and exchanges labels between routers. Each router will locally generate labels for its prefixes and will then advertise the label values to its neighbors. It's a standard, based on Cisco's proprietary TDP (Tag Distribution Protocol). Nowadays almost everyone uses LDP instead of TDP.
LDP first establishes a neighbor adjacency before it exchanges label information. It works a bit differently than most protocols though. LIB functions in the control plane of router's MPLS layer. It is used by the label distribution protocol for mapping the next hop labels.
Sources and credits
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