OSPF Network Types and Implementing Multiarea

What are the default hello timers in OSPF for the following? Broadcast and point-to-point links: All other OSPF network types:

-Broadcast and point-to-point links: 10 seconds -All other OSPF network types: 30 seconds

What are the conditions when electing DR/BDR?

-The router with the highest OSPF priority will be elected as DR -The router with the second-highest OSPF priority will be elected as BDR -If there is a tie of priority values the router ID is used (highest router ID becomes DR and second highest the BDR) -If the router priority is set to 0 it does not participate in the DR/BDR election and is not eligible to become DR/BDR

Which two network types elect a DR? (Choose two.) -broadcast -nonbroadcast -point-to-multipoint -point-to-point -multipoint-to-multipoint

-broadcast -nonbroadcast

What is the default OSPF interface priority value?

1

In this OSPF router state the router receives its own router ID in a hello. Interface has bidirectional communication with neighbor. Also at the end of this stage the DR/BDR election would be performed and router must decide whether to proceed in building an adjacency

2-WAY

This OSPF network type has the following characteristics: -Uses multicast to dynamically discover neighbors -Default network type for Ethernet links -Has DR/BDR

Broadcast

What is a router called that is not the DR or BDR

DROTHER

What are the seven states an OSPF router progresses through?

Down INIT 2-WAY Exstart Exchange Loading Full

In this OSPF router state database description (DBD) packets where the entire LSDB are sent. In this state packets may be flooded to other interfaces on the router

Exchange

In this OSPF router state primary and secondary roles are determined. Routers are trying to establish the initial sequence number that is going to be used in the information exchange packets

Exstart

In this OSPF router state neighbors are fully adjacent. Adjacent routers will have similar LSDBs

Full

In this OSPF router state a Hello packet is received from the neighbor but bidirectional communication has not yet been established

INIT

In this OSPF router state LSRs and LSUs are exchanged finalizing information exchange. Routers will put any information that looks incomplete or outdated on a link-state request list and any update that is sent will be put on the retransmission list until it gets acknowledged

Loading

This OSPF network type has the following characteristics: -Default network type on loopback interfaces

Loopback

This OSPF network type has the following characteristics: -This network type is used on networks that interconnect more than two routers but without broadcast capability. -Frame Relay and ATM are examples -Neighbors are statically configured -default for all physical interfaces and multipoint subinterfaces using Frame Relay encapsulation. -Has DR/BDR

Nonbroadcast Multiaccess (NBMA)

What are the 6 OSPF network types

Point-to-Point Broadcast Nonbroadcast Multiaccess (NBMA) Point-to-multipoint Point-to-multipoint nonbroadcast Loopback

This OSPF network type has the following characteristics: -Neighbors are discovered dynamically using multicast. -OSPF treats this network type as a logical collection of point-to-point links, although all interfaces belong to the common IP subnet

Point-to-multipoint

This OSPF network type has the following characteristics: -Cisco extension that has the same characteristics as point-to-multipoint, except that neighbors are not discovered dynamically. -unicast is used for communication -Useful when multicast and broadcast are not supported

Point-to-multipoint nonbroadcast

This OSPF network type has the following characteristics: -Uses multicast to dynamically discover neighbors -Default network type for serial links and point-to-point Frame Relay subinterfaces

Point-to-point

Electing a DR/BDR improves network functioning in what 2 ways?

Reducing routing update traffic managing link-state synchronization

How can you change the OSPF network type?

Use the interface configuration mode command ip ospf network network_type

Mismatched MTUs can lead to what?

an inconsistent OSPF database.

OSPF requires the same MTUs to be configured on both sides of the link. If OSPF neighbors have mismatched MTUs what state are the stuck in?

with mismatched MTUs are stuck in the EXSTART adjacency state.