Chapter 7, “Understanding OSPF Concepts,” introduced you to the concepts, so this chapter moves on to the implementation details for Open Shortest Path First Version 2 (OSPFv2)—that is, OSPF as used for IPv4. This chapter looks at how to configure and verify a variety of OSPFv2 features.
This chapter touches on a wide variety of configuration options, so it breaks the content down into the three major sections. The first major section shows how to configure and verify basic OSPFv2 with a single-area design. With a single area, all interfaces sit in the same area, and that fact has an impact on the kinds of information lists in show command output. Also, the first section uses traditional OSPFv2 configuration using the OSPF network command. The second major section repeats the same kinds of configuration and verification as in the first major section, but now with multiarea OSPF designs.
The third major section of the chapter looks at a variety of common OSPFv2 features. These features include a completely different way to enable OSPFv2 on a Cisco router, using interface subcommands rather than the OSPF network command. It also includes the configuration of OSPF default routes, tuning OSPF metrics, and OSPF load balancing.
Finally, take a moment to reread the exam topics at the top of this page. Note that the exam topics specifically exclude some OSPF topics.
“Do I Know This Already?” Quiz
Take the quiz (either here, or use the PCPT software) if you want to use the score to help you decide how much time to spend on this chapter. The answers are at the bottom of the page following the quiz, and the explanations are in DVD Appendix C and in the PCPT software.
Table 8-1 “Do I Know This Already?” Foundation Topics Section-to-Question Mapping
Foundation Topics Section
Implementing Single-Area OSPFv2
Implementing Multiarea OSPFv2
Additional OSPFv2 Features
Which of the followingnetwork commands, following the command router ospf 1, tells this router to start using OSPF on interfaces whose IP addresses are 10.1.1.1, 10.1.100.1, and 10.1.120.1?
network 10.0.0.0 255.0.0.0 area 0
network 10.0.0.0 0.255.255.255 area 0
network 10.0.0.1 0.0.0.255 area 0
network 10.0.0.1 0.0.255.255 area 0
Which of the following network commands, following the command router ospf 1, tells this router to start using OSPF on interfaces whose IP addresses are 10.1.1.1, 10.1.100.1, and 10.1.120.1?
network 10.1.0.0 0.0.255.255 area 0
network 10.0.0.0 0.255.255.0 area 0
network 10.1.1.0 0.x.1x.0 area 0
network 10.1.1.0 255.0.0.0 area 0
network 10.0.0.0 255.0.0.0 area 0
Which of the following commands list the OSPF neighbors off interface serial 0/0? (Choose two answers.)
show ip ospf neighbor
show ip ospf interface brief
show ip neighbor
show ip interface
show ip ospf neighbor serial 0/0
Routers R1, R2, and R3 are internal routers in areas 1, 2, and 3, respectively. Router R4 is an ABR connected to the backbone area (0) and to areas 1, 2, and 3. Which of the following answers describes the configuration on Router R4, which is different from the other three routers, that makes it an ABR?
The abr enable router subcommand.
The network router subcommands refer to a single nonbackbone area.
The network router subcommands refer to multiple areas, including the backbone.
The router has an interface in area 0, whereas an OSPF neighbor’s interface sits in a different area.
An engineer connects to Router R1 and issues a show ip ospf neighbor command. The status of neighbor 220.127.116.11 lists FULL/BDR. What does the BDR mean?
R1 is an Area Border Router.
R1 is a backup designated router.
Router 18.104.22.168 is an Area Border Router.
Router 22.214.171.124 is a backup designated router.
An engineer migrates from a more traditional OSPFv2 configuration that uses network commands in OSPF configuration mode to instead use OSPFv2 interface configuration. Which of the following commands configures the area number assigned to an interface in this new configuration?
The area command in interface configuration mode
The ip ospf command in interface configuration mode
The router ospf command in interface configuration mode
The network command in interface configuration mode
Which of the following configuration settings on a router does not influence which IPv4 route a router chooses to add to its IPv4 routing table when using OSPFv2?
ip ospf cost
Answers to the “Do I Know This Already?” quiz: