BGP—Border Gateway Protocol. An interdomain routing protocol that replaces Exterior Gateway Protocol (EGP). A BGP system exchanges reachability information with other BGP systems. It is defined by RFC 1163.
CE device—customer edge device. A device that is part of a customer network and that interfaces to a provider edge (PE) device. CE devices do not have routes to associated Virtual Private Networks (VPNs) in their routing tables.
FEC—Forwarding Equivalence Class. A set of packets that can be handled equivalently for the purpose of forwarding and thus is suitable for binding to a single label. The set of packets destined for an address prefix is one example of an FEC.
IGP—Interior Gateway Protocol. Internet protocol used to exchange routing information within a single autonomous system. Examples of common Internet IGP protocols include Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF), Intermediate System-to-Intermediate System (IS-IS), and Routing Information protocol (RIP).
label—A short fixed-length label that tells switching nodes how to forward data (packets or cells).
LDP—Label Distribution Protocol. A standard protocol between Multiprotocol Label Switching (MPLS)-enabled devices that is used for the negotiation of the labels (addresses) used to forward packets.
LIB—Label Information Base. A database used by a label switch router (LSR) to store labels learned from other LSRs, and labels assigned by the local LSR.
LSP—label switched path. A sequence of hops in which a packet travels from one device to another device by means of label switching mechanisms. A label switched path can be established dynamically, based on normal routing mechanisms, or through configuration.
LSR—label switch router. A device that forwards Multiprotocol Label Switching (MPLS) packets based on the value of a fixed-length label encapsulated in each packet.
MPLS—Multiprotocol Label Switching. A switching method that forwards IP traffic using a label. This label instructs the devices and the switches in the network where to forward the packets. The forwarding of MPLS packets is based on preestablished IP routing information
PE device—provider edge device. A device that is part of a service provider’s network connected to a customer edge (CE) device. All Virtual Private Network (VPN) processing occurs in the PE device.
VPN—Virtual Private Network. A secure IP-based network that shares resources on one or more physical networks. A VPN contains geographically dispersed sites that can communicate securely over a shared backbone.