--Area Border Router. A routers connecting two areas.
--The MPLS TE Forwarding Adjacency feature allows a network administrator to handle a traffic engineering, label-switched
path (LSP) tunnel as a link in an Interior Gateway Protocol (IGP) network based on the Shortest Path First (SPF) algorithm.
A forwarding adjacency can be created between routers regardless of their location in the network. The routers can be located
multiple hops from each other.
--A logical set of network segments (for example, one that is OSPF-based) and their attached devices. Areas usually are connected
to other areas by routers, making up a single autonomous system. OSPF and IS-IS define their areas differently. OSPF area
borders are marked by routers. Some interfaces are in one area, and other interfaces are in another area. With IS-IS, all
the routers are completely within an area, and the area borders are on links, not on routers. The routers that connect the
areas are level-2 routers, and routers that have no direct connectivity to another area are level-1 routers.
--Autonomous System Boundary Router. The router is located between an OSPF autonomous system and a non-OSPF network. ASBRs
run both OSPF and another routing protocol, such as RIP. ASBRs must reside in a nonstub OSPF area.
--A collection of networks under a common administration sharing a common routing strategy. Autonomous systems are subdivided
--An MPLS traffic engineering tunnel used to protect other (primary) tunnel’s traffic when a link or node failure occurs.
--Border Gateway Protocol. Interdomain routing protocol that replaces EGP. BGP exchanges reachability information with other
--A router at the edge of a provider network that interfaces to another provider’s border router using extended BGP procedures.
--A means for accelerating the forwarding of packets within a router, by storing route lookup information in several data
structures instead of in a route cache.
--A mechanism for protecting MPLS traffic engineering (TE) LSPs from link and node failure by locally repairing the LSPs at
the point of failure, allowing data to continue to flow on them while their headend routers attempt to establish end-to-end
LSPs to replace them. FRR locally repairs the protected LSPs by rerouting them over backup tunnels that bypass failed links
--A traffic-passing technique used by switches and bridges in which traffic received on an interface is sent out all the interfaces
of that device except the interface on which the information was received originally.
--A traffic engineering link (or LSP) into an IS-IS or OSPF network.
--The router that originates and maintains a given LSP. This is the first router in the LSP’s path.
--Passage of a data packet between two network nodes (for example, between two routers).
--Interior Gateway Protocol. Internet protocol used to exchange routing information within an autonomous system. Examples
of common IGPs include Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF), and Routing Information
--An MPLS traffic engineering label-switched path (LSP) that traverses hops that are not in the headend’s topology database
(that is, it is not in the same OSPF area, IS-IS area, or autonomous system as the headend).
--A network connection.
--A list of IP addresses, each representing a node or link in the explicit path.
--Intermediate System-to-Intermediate System. OSI link-state hierarchal routing protocol based on DECnet Phase V routing,
where intermediate system (IS) routers exchange routing information based on a single metric to determine the network topology.
--A point-to-point connection between adjacent nodes.
--link-state advertisement. A broadcast packet used by link-state protocols that contains information about neighbors and
path costs. LSAs are used by the receiving routers to maintain their routing tables.
--label-switched path. A configured connection between two routers, in which MPLS is used to carry packets. An LSP is a path
created by the concatenation of one or more label-switched hops, allowing a packet to be forwarded by swapping labels from
an MPLS node to another MPLS node.
--A transit router for a given LSP.
--Ability of a midpoint to trigger a headend reoptimization.
--merge point. The LSR where one or more backup tunnels rejoin the path of the protected LSP, downstream of the potential
failure. An LSR can be both an MP and a PLR simultaneously.
--Multiprotocol Label Switching. Packet-forwarding technology, used in the network core, that applies data link layer labels
to tell switching nodes how to forward data, resulting in faster and more scalable forwarding than network layer routing normally
--Single packets are copied by the network and sent to a specific subset of network addresses. These addresses are specified
in the Destination address field. (Multicast is an efficient paradigm for transmitting the same data to multiple receivers,
because of its concept of a Group address. This allows a group of receivers to listen to the single address.)
--Endpoint of a network connection or a junction common to two or more lines in a network. Nodes can be interconnected by
links, and serve as control points in the network.
--Open Shortest Path First. A link-state, hierarchical Interior Gateway Protocol routing algorithm, derived from the IS-IS
protocol. OSPF features include least-cost routing, multipath routing, and load balancing.
--If a router understands LSA Type 10 link information, the router continues flooding the link throughout the network.
--When IGP is not running on the link between two ASBRs, traffic engineering informs the IGP to flood link information on
behalf of that link (that is, it advertises that link).
--point of local repair. The headend LSR of a backup tunnel.
--A network layer device that uses one or more metrics to determine the optimal path along which network traffic should be
forwarded. Routers forward packets from one network to another based on network layer information.
--Resource Reservation Protocol. An IETF protocol used for signaling requests (setting up reservations) for Internet services
by a customer before that customer is permitted to transmit data over that portion of the network.
--shortest path first. A routing algorithm used as the basis for OSPF operations. When an SPF router is powered up, it initializes
its routing-protocol data structures and then waits for indications from lower-layer protocols that its interfaces are functional.
--Shared Risk Link Group. Sets of links that are likely to go down together (for example, because they have the same underlying
--The router upon which an LSP is terminated. This is the last router in the LSP’s path.
--traffic engineering. The techniques and processes used to cause routed traffic to travel through the network on a path other
than the one that would have been chosen if standard routing methods had been used.
--type, length, values. A block of information embedded in Cisco Discovery Protocol advertisements.