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Admission control
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Accounting mechanism that tracks resource information. Prevents requests from being accepted if sufficient resources are not available.
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BGP
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Border Gateway Protocol, which provides loop-free interdomain routing between autonomous systems (ASs) and can act as a label distribution protocol for MPLS.
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Constraint-based routing
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A mechanism to establish paths based on certain criteria (explicit route, QoS parameters). The standard routing protocols can be enhanced to carry additional information to be used when running the route calculation.
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E-LSP
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EXP-inferred-PSC LSP. The EXP field of the MPLS Shim Header is used to determine the per-hop behavior applied to the packet.
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Explicit routing
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A subset of constraint-based routing where the constraint is an explicit route
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FEC
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Forwarding equivalence class—Group of IP packets forwarded over the same path with the same path attributes applied
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Label Distribution Protocol
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- A particular label distribution protocol used for label distribution among the routers in an MPLS domain; represented by the acronym LDP
- In lowercase—label distribution protocol—a generic term for any of several protocols that distribute labels among the routers in an MPLS domain, including BGP, LDP, and RSVP-TE. This usage is not represented in this text by the acronym, LDP.
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LDP
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Label Distribution Protocol—A particular protocol used for label distribution among the routers in an MPLS domain
This text does not use LDP to refer to the generic class of label distribution protocols.
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LER
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Label edge router—A label-switching router serving as an ingress or egress nodes
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LSP
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Label-switched path—The path traversed by a packet that is routed by MPLS. Some LSPs act as tunnels.
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LSP priority level
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A priority that indicates the importance of one LSP relative to another LSP. LSPs having higher priorities can preempt LSPs having lower priorities. Priorities range from 0 through 7 in order of decreasing priority.
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L-LSP
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Label-only-inferred-PSC LSP. The label value, and possibly the EXP-bits, are used to determine the per-hop behavior applied to the packet.
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LSR
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Label-switching router—An MPLS node that can forward layer 3 packets based on their labels
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MPLS
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Multiprotocol Label Switching—Set of techniques enabling forwarding of traffic using layer 2 and layer 3 information
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MPLS edge node
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MPLS node that connects an MPLS domain with a node outside the domain that either does not run MPLS or is in a different domain
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MPLS egress node
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MPLS edge node in the role of handling traffic as it leaves an MPLS domain
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MPLS ingress node
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MPLS edge node in the role of handling traffic as it enters an MPLS domain
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MPLS label
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Label carried in a packet header that represents a packet's forwarding equivalence class
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MPLS node
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A router running MPLS. An MPLS node is aware of MPLS control protocols, operates one or more L3 routing protocols, and is capable of forwarding packets based on labels. Optionally, an MPLS node can be capable of forwarding native L3 packets.
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Provider edge router
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PE—An LER at the edge of a service provider core that provides ingress to or egress from a VPN
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Provider core router
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P—An LSR within a service provider core that carries traffic for a VPN
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RSVP
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Resource Reservation Protocol; E-series routers do not support RSVP
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RSVP-TE
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Resource Reservation Protocol enhanced to support MPLS traffic engineering; E-series routers support RSVP-TE
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Traffic engineering
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The ability to control the path taken through a network or portion of a network based on a set of traffic parameters (bandwidth, QoS parameters, and so on). Traffic engineering (TE) enables performance optimization of operational networks and their resources.
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Tunnel
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LSP that is used by an IGP to reach a destination, or an LSP that uses traffic engineering
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