backup bandwidth --The usage of NHOP and NNHOP backup tunnels to provide bandwidth protection for rerouted LSPs.
backup tunnel --An MPLS TE tunnel used to protect other (primary) tunnels' traffic when a link or node failure occurs.
bandwidth --The available traffic capacity of a link.
fast reroute --Procedures that enable temporary routing around a failed link or node while a new LSP is being established at the headend.
global pool --The total bandwidth allocated to an MPLS traffic engineering link or node.
headend --The router that originates and maintains a given LSP. This is the first router in the LSP's path.
hop --Passage of a data packet between two network nodes (for example, between two routers).
instance --A Hello instance implements the RSVP Hello extensions for a given router interface address and remote IP address. Active Hello instances periodically send Hello Request messages, expecting Hello ACK messages in response. If the expected Ack message is not received, the active Hello instance declares that the neighbor (remote IP address) is unreachable (that is, it is lost). This can cause LSPs crossing this neighbor to be fast rerouted.
interface --A network connection.
link --A point-to-point connection between adjacent nodes. There can be more than one link between adjacent nodes. A network communications channel consisting of a circuit or transmission path and all related equipment between a sender and a receiver. Sometimes referred to as a line or a transmission link.
LSP --label-switched path. A configured connection between two routers, in which label switching is used to carry the packets. The purpose of an LSP is to carry data packets.
MPLS --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 can do.
NHOP --next hop. The next downstream node along an LSP's path.
NHOP backup tunne l--next-hop backup tunnel. Backup tunnel terminating at the LSP's next hop beyond the point of failure, and originating at the hop immediately upstream of the point of failure. It bypasses a failed link, and is used to protect primary LSPs that were using this link before the failure.
NNHOP --next-next hop. The node after the next downstream node along an LSP's path.
NNHOP backup tunnel --next-next-hop backup tunnel. Backup tunnel terminating at the LSP's next-next hop beyond the point of failure, and originating at the hop immediately upstream of the point of failure. It bypasses a failed link or node, and is used to protect primary LSPs that were using this link or node before the failure.
node --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. Computers on a network, or any endpoint or a junction common to two or more lines in a network. Nodes can be processors, controllers, or workstations.
primary LSP --The last LSP originally signaled over the protected interface before the failure. The LSP before the failure.
primary tunnel --Tunnel whose LSP may be fast rerouted if there is a failure. Backup tunnels cannot be primary tunnels.
protected interface --An interface that has one or more backup tunnels associated with it.
redundancy --The duplication of devices, services, or connections so that, in the event of a failure, the redundant devices, services, or connections can perform the work of those that failed.
RSVP --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.
state --Information that a router must maintain about each LSP. The information is used for rerouting tunnels.
subpool --The more restrictive bandwidth in an MPLS traffic engineering link or node. The subpool is a portion of the link or node's overall global pool bandwidth.
tailend --The router upon which an LSP is terminated. This is the last router in the LSP's path.
tunnel --Secure communications path between two peers, such as two routers.