Ospf

Front 1

Formed when two neighboring routers have exchanged information and have the same topology table

Back 1

Adjacency

Front 2

A group of routers that share the same area ID.

Back 2

Area

Front 3

Routers that share the same routing protocol within the organization.

Back 3

Autonomous system

Front 4

The metric for OSPF.

Back 4

Cost

Front 5

DBD

Back 5

Database descriptor: These
are packets exchanged between neighbors during the exchange state.
The DDPs contain partial LSAs, which summarize the links of everyrouter in the neighbor’s topology table.

Front 6

Router responsible for making adjacencies with all neighbors on a multiaccess network,

Back 6

Designated router (DR)

Front 7

what is used to calculate SPF?

Back 7

Dijkstra algorithm

Front 8

Exchange state

Back 8

State in which two neighboring routers discover the map of the network. When these routers become adjacent, they must firstexchange DDPs to ensure that they have the same topology table.

Front 9

Exstart state

Back 9

State in which the neighboring routers determine the sequence
number of the DDPs and establish the master/slave relationship.

Front 10

Fully adjacent

Back 10

When the routing tables of the two neighbors are fully synchronized,with exactly the same view of the network.

Front 11

Init state

Back 11

State in which a hello packet has been sent from the router, which is
waiting for a reply to establish two-way communication.

Front 12

Link-state advertisement (LSA)

Back 12

A packet describing a router’s links and the state of those links.

Front 13

Link-state database

Back 13

the link-state database has a
map of every router, its links, and the state of the links.

Front 14

LSR

Back 14

When the router receives a DDP complete with a partial LSA, it compares the summarized information against the topological database. If either the LSA entry is not present or the entry is older than the DDP, it will request further information.

Front 15

LSU

Back 15

Update sent in response to the LSR. It is the LSA that was requested.

Front 16

Loading state

Back 16

State in which, if the receiving router requires more information during the process in which two routers are creating an adjacency, it will request that particular link in more detail using the LSR packet.
The LSR will prompt the master router to send the LSU packet. This
is the same as an LSA used to flood the network with routing
information. While the receiving router is awaiting the LSUs from its neighbor, it is in the loading state.

Front 17

A table built from the hello messages received from the neighbors.

Back 17

Neighbor table

Front 18

A Cisco tool by which the DR can be manually elected or, conversely, prevented from taking part in the DR/BDR election.

Back 18

Priority

Front 19

SPF tree

Back 19

A tree of the topological network. It can be drawn after the SPF
algorithm has been run. The algorithm prunes the database of alternative paths and creates a loop-free shortest path to all networks.

Front 20

difference between Topology table and link-state database

Back 20

;) nothing

Front 21

In a topology table he _______ is at the root of the network, which is perceived from its perspective.

Back 21

router

Front 22

Two-way state

Back 22

State during the process in which two routers are creating an adjacency. The new router sees its own router ID in the list of neighbors, and a neighbor relationship is established. This is the stage before routing information is exchanged.

Front 23

OSPF discovers its neighbors by sending and receiving a simple protocol called

Back 23

Hello protocol.

Front 24

OSPF sends out a small hello packet how periodically?

Back 24

10 seconds is the default
on broadcast multiaccess media

Front 25

source and destination of hello packet?

Back 25

source address of the router and a multicast destination
address set to AllSPFRouters (224.0.0.5)

Front 26

To ensure that the link is maintained and the topology databases are up to date, what is done?

Back 26

the hello protocol keeps transmitting

Front 27

Advantages of Having Neighbors

Back 27

* It is a mechanism for determining that a router has gone down
*Streamlined communication
*Adjacencies created between neighbors control the distribution of the routing protocol packets.

Front 28

The election is determined by either _____ or _____

Back 28

the highest IP address or
Router(config-if)#ip ospf priority number

Front 29

In Router(config-if)#ip ospf priority number...
The number in the priority command can be set between ___

Back 29

0–255

Front 30

DRs are created on _____ links

Back 30

multiaccess

Front 31

the number of adjacencies required for a full mesh is ___

Back 31

n(n-1)/2

Front 32

the number of adjacencies required for DR/BDR situation is ___

Back 32

2n-2

Front 33

each router must form an
adjacency with every other router on the segment in ___ kind of network

Back 33

FDDI ring

Front 34

If one router is elected foreman of the link, responsible for maintaining adjacencies and forwarding
updates, this dramatically reduces the __________________

Back 34

overhead on the network.

Front 35

The priority value of 0 means _____________

Back 35

that the router cannot be a
DR or BDR

Front 36

steps in election of DR:
1)

2)

3)

4)

5)

Back 36

1) All the neighbors who have a priority greater than 0 are listed.
2) The neighbor with the highest priority is elected as the BDR.
3) If there is no DR, the BDR is promoted as DR.
4) From the remaining routers, the router with the highest priority is elected as the BDR.
5) If the priority has not been configured, there will be a tie, because the default is to set the priority
to 1.
6) If there is a tie because the priority has not been configured, the highest router IDs are used.

Front 37

in the hello packet what is version #

Back 37

The version of OSPF, which is
currently version 2

Front 38

what is the dead interval?

Back 38

The dead interval is how long the router waits before it determines that a neighbor is unavailable because it has not heard a hello packet within the prescribed time, that is, four times the hello timer.

Front 39

Routing tables are built in two different ways:
1____________

2____________

Back 39

1) established databases have to adjust to a change
in the network
2) New router has to create the topology and forwarding databases when it enters
the network :P

Front 40

Hello protocol exchange packets when?

Back 40

a new router connects to a network

Front 41

Hello protocol floodarea with packets when?

Back 41

If a change occurs in an existing network

Front 42

which five packets are used to build the table?

Back 42

Hello protocol
Database descriptor
LSR
LSU
Link-state acknowledgement

Front 43

The different stages or states that the router goes through while creating a neighbor relationship are:

Back 43

1. The down state
2. The init state
3. The two-way state—

Front 44

The different stages or states that the router goes through while exchanging routing information with
a neighbor are:

Back 44

1. The exstart state
2. The exchange state
3. The loading state
4. The full state

Front 45

The topology database is updated by the

Back 45

LSA

Front 46

The synchronization of the topology maps is ensured by

Back 46

the intricate use of sequence numbers in the LSA headers.

Front 47

Although RFC 2328 does not state the number of multiple, equal-cost paths that can be
used at the same time, Cisco has defined a maximum of ___ paths that can be used simultaneously
for load balancing.

Back 47

six

Front 48

Typically, a router will identify a change in the
state of one of its links for one of the following reasons(3):

Back 48

■ The router loses the physical or data link layer connectivity on a connected network.
■ The router fails to hear either an OSPF Hello protocol or a data link Hello protocol.
■ The router receives an LSA update from an adjacent neighbor, informing it of the change in the network topology

Front 49

When the 2500 router receives a network LSA update from the DR, it goes through the following
logical steps:

Back 49

refer 16 points on page 248

Front 50

OSPF identifies five distinct network types or technologies:

Back 50

■ Broadcast multiaccess
■ Point-to-point
■ Point-to-multipoint
■ Nonbroadcast multiaccess (NBMA)
■ Virtual links

Front 51

Broadcast multiaccess

Back 51

any LAN network, such as Ethernet, Token Ring, or FDDI.

Front 52

In Broadcast multiaccess
environment, OSPF sends

Back 52

multicast traffic

Front 53

Point-to-point technology is used where

Back 53

there is only one other router directly connected to the
transmitting or receiving router

Front 54

OSPF has no need for a
DR or BDR in this scenario

Back 54

Point-to-point

Front 55

Point-to-multipoint is

Back 55

a single interface that connects to multiple destinations.

Front 56

OSPF traffic in a point-to-Multipoint Network is sent as

Back 56

multicast.

Front 57

There is DR or BDR election in Point-to-Multipoint Network: T/F

Back 57

False

Front 58

NBMA examples are:

Back 58

WAN clouds, including X.25 and Frame Relay

Front 59

NBMA uses a _________ or ________ meshed network.

Back 59

fully meshed or partially meshed network.

Front 60

This technology requires manual configuration of the neighbors and the DR and BDR selection.

Back 60

NBMA

Front 61

A virtual link is

Back 61

a virtual connection to a remote area that does not have any connections to the
backbone (Area 0)

Front 62

The OSPF network traffic is sent in ________________ across virtual links

Back 62

unicast datagrams

Front 63

The NBMA technology is then subdivided into two categories, under which different configuration
options are available:

Back 63

■ RFC-compliant (— NBMA — Point-to-multipoint)
■ Cisco-specific (— Point-to-multipoint nonbroadcast — Broadcast
— Point-to-point)

Front 64

The Frame Relay topologies include:

Back 64

■ Full mesh
■ Partial mesh
■ Star, or hub and spoke

Front 65

For serial interfaces with HDLC encapsulation, the default network type is ____________ and
Timers: ____________

Back 65

point-to-point
hello 10, dead 40.

Front 66

For serial interfaces with Frame Relay encapsulation, the default network type is ____________ and
Timers: ____________

Back 66

nonbroadcast
hello 30, dead 120.

Front 67

For serial interfaces with Frame Relay encapsulation and using point-to-point subinterfaces,, the default network type is ____________ and Timers: ____________

Back 67

point-to point.
hello 10, dead 40

Front 68

For serial interfaces with Frame Relay encapsulation and using point-to-multipoint
subinterfaces, the default network type is ____________ and Timers: ____________

Back 68

point-to-multipoint
hello 30, dead 120.