User guide

MPLS Module Installation and User Guide 3-3
Overview of MPLS
DU Downstream Unsolicited. Distribution of labels downstream without an
explicit label request.
FEC Forward Equivalence Class. A group of packets that are forwarded in
the same manner (for example, over the same Label Switched Path).
Label A short, fixed-length identifier used to forward packets from a given
link.
Label stack A set of one or more MPLS labels used by MPLS to forward packets
to the appropriate destination.
Label swapping Lookup and replacement of an incoming label with the appropriate
outgoing label.
LDP Label Distribution Protocol. A protocol defined by the IETF used to
establish an MPLS Label Switched Path (LSP).
LER Label Edge Router. A Label Switch Router that is at the beginning
(ingress) or end (egress) of a Label Switched Path.
LSP Label Switched Path. The unidirectional MPLS connection between
two routers over which packets are sent.
LSR Label Switch Router. A router that receives and transmits packets on
an MPLS network.
MPLS MultiProtocol Label Switching. A set of protocols defined by the IETF
used to transmit information based on a label-switching forwarding
algorithm.
NHLFE Next Hop Label Forwarding Entry. The NHLFE represents the MPLS
router next hop along the LSP.
PHP Penultimate Hop Popping. A label stack optimization used for
conserving the number of allocated labels.
RSVP Resource ReSerVation Protocol. A resource setup protocol designed
for an integrated services network.
RSVP-TE The combination of RSVP and MPLS label signaling to provide traffic
engineered LSPs as specified in draft-ietf-mpls-rsvp-lsp-tunnel-09.txt.
Shim header MPLS-specific header information that is inserted between layer-2
and layer-3 information in the data packet.
SP Service Provider. An entity that provides network services for
individuals or organizations.
TE Traffic Engineering. The provisioning of an autonomous flow along a
specified network path.
TLS Transparent LAN Services. A method for providing layer-2 virtual
private networks (VPNs).
Table 3-1: MPLS Terms and Acronyms (continued)
Term or Acronym Description