Editing Multiprotocol Label Switching (section)

====Label switch router====
An MPLS router that performs routing based only on the label is called a '''label switch router''' ('''LSR''') or '''transit router'''. This is a type of router located in the middle of an MPLS network. It is responsible for switching the labels used to route packets.

When an LSR receives a packet, it uses the label included in the packet header as an index to determine the [[Per-hop behavior|next hop]] on the label-switched path (LSP) and a corresponding label for the packet from a [[Label Information Base]]. The old label is then removed from the header and replaced with the new label before the packet is routed forward.