Chapter 8 - OSPF

Question 1

backup designated router (BDR)

Answer 1

A backup pseudonode that maintains the network segment’s state to replace the DR in the event of its failure.

Question 2

dead interval

Answer 2

The amount of time required for a hello packet to be received for the neighbor to be deemed healthy. Upon receipt, the value resets and decrements toward zero.

Question 3

designated router (DR)

Answer 3

A pseudonode to manage the adjacency state with other routers on the broadcast network segment.

Question 4

hello interval

Answer 4

The frequency at which hello packets are advertised out an interface.

Question 5

hello packets

Answer 5

Packets that are sent out at periodic interval to detect neighbors for establishing adjacency and ensuring that neighbors are still available.

Question 6

interface priority

Answer 6

The reference value for an interface to determine preference for being elected as the designated router.

Question 7

passive interface

Answer 7

An interface that has been enabled with a routing protocol to advertise its associated interfaces into its RIB but that does not establish neighborship with other routers associated to that interface.

Question 8

router ID (RID)

Answer 8

A 32-bit number that uniquely identifies the router in a routing domain.

Question 9

shortest path tree (SPT)

Answer 9

A router’s view of the topology to reach all destinations in the topology, where the router is the top of the tree, and all of the destinations are the branches of the tree. In the context of multicast, the SPT provides a multicast distribution tree where the source is the root of the tree and branches form a distribution tree through the network all the way down to the receivers. When this tree is built, it uses the shortest path through the network from the source to the leaves of the tree.