LSR - Computer Definition
In Multiprotocol Label Switching (MPLS), a router in the network core that forwards packets along paths consistent with the labels inserted into packet headers by Label Edge Routers (LERs) as they entered the network. The LERs employ a Label Distribution Protocol (LDP) to distribute labels to the LSRs in the network core. As the LSRs receive the packets, they examine the short labels, compare them against a label database, switch the existing label for a new one, and quickly forward the packet across an appropriate link to the next LER. The process is repeated by each LSR until the packet reaches the egress LER, which strips the tag away as the packet exits the network. See also core, header, link, LSP, LDP, LER, MPLS, packet, path, router, and switch.