Chapter 19 Flashcards
(22 cards)
Convergence
This happens when there is a topology change. For example, if a link fails, an advertisement is sent to let other routers know that that route has failed which it then chooses an alternate best route.
Shortest Path First (SPF) Algorithm
The name of the algorithm used by link-state routing protocols to analyze the LSDB and find the least-cost routes from that router to each subnet.
Distance Vector
The logic behind the behavior of some interior routing protocols, such as RIP. Distance vector routing algorithms call for each router to send its entire routing table in each update, but only to its neighbors. Distance vector routing algorithms can be prone to routing loops but are computationally simpler than link-state routing algorithms.
Interior Gateway Protocol (IGP)
A routing protocol that was designed and intended for use inside a single autonomous system (AS).
Link-state
A classification of the underlying algorithm used in some routing protocols. Link-state protocols build a detailed database that lists links (subnets) and their state (up, down), from which the best routes can then be calculated.
Link-state Advertisement
In OSPF, the name of the data structure that resides inside the LSDB and describes in detail the various components in a network, including routers and links (subnets).
Link-state Database
In OSPF, the data structure in RAM of a router that holds the various LSAs, with the collective LSAs representing the entire topology of the network.
Metric
A unit of measure used by routing protocol algorithms to determine the best route for traffic to use to reach a particular destination.
2-way State
In OSPF, a neighbor state that implies that the router has exchanged Hellos with the neighbor and that all required parameters match.
Full State
In OSPF, a neighbor state that implies that the two routers have exchanged the complete (full) contents of their respective LSDBs.
Area Border Router
A router using OSPF in which the router has interfaces in multiple OSPF areas.
Designated Router
In OSPF, on a multiaccess network, the router that wins an election and is therefore responsible for managing a streamlined process for exchanging OSPF topology information between all routers attached to that network.
Backup Designated Router
An OSPF router connected to a multiaccess network that monitors the work of the designated router (DR) and takes over the work of the DR if the DR fails.
Fully Adjacent
In OSPF, a characterization of the state of a neighbor in which the two neighbors have reached the full state.
Hello Interval
With OSPF and EIGRP, an interface timer that dictates how often the router should send Hello messages.
Dead Interval
In OSPF, a timer used for each neighbor. A router considers the neighbor to have failed if no Hellos are received from that neighbor in the time defined by the timer.
Link-state Update
An OSPF packet used to send an LSA to a neighboring router.
Neighbor
In routing protocols, another router with which a router decides to exchange routing information.
Router ID (RID)
In EIGRP and OSPF, a 32-bit number, written in dotted-decimal notation, that uniquely identifies each router.
Topology Database
The structured data that describes the network topology to a routing protocol. Link-state and balanced hybrid routing protocols use topology tables, from which they build the entries in the routing table.
Internal Router
In OSPF, a router with all interfaces in the same nonbackbone area.
Backbone Area
In OSPFv2 and OSPFv3, the special area in a multiarea design, with all non-backbone areas needing to connect to the backbone area, area 0.
