OSPF: Cert Guide PT Labs for ICND2 Chapter 8

By certskills September 2, 2019 09:05

The CCNA 200-125 exam includes OSPF as one of several routing protocols (RIP, EIGRP, OSPF, BGP). The new CCNA 200-301 has OSPF, and OSPF only. This post details how to take advantage of some Packet Tracer files to re-create the examples in the book from the ICND2 200-105 Cert Guide, Chapter 8, which discusses OSPF configuration and verification.

Advice before You Begin

The big idea is pretty simple: Repeat the Examples in the Official Cert Guide as part of your lab practice for CCNA.

To get your head around what kind of content is here in the blog for these labs, read both of these posts or at least the second post:

After reading those posts, you have the context, so onward to the details!


What’s in This Post

Intro to the Book Chapter: A brief description of the topics in that chapter of the book.

Chapter Examples and .PKT File Reference: A section that lists the examples in the chapter, the .pkt files supplied, and reminders/notes about cases in which we don’t supply all three files for any one example.

Tips and Exceptions: When we build the files, we come across items that we think might confuse you when trying the examples with PT. We write those notes in this section!


Intro to the Book Chapter

Chapter 8 of the ICND2 200-105 Cert Guide has 22 examples, more than most any chapter in that generation of the books. The examples range widely, from single-area OSPF, multiarea, and then into a number of optional configuration settings, like OSPF Router IDs, passive interfaces, default routes, and metrics. It also includes details on how to configure using OSPF interface configuration commands.

Even though it sounds long, it is straightforward: It describes a configuration feature, shows the feature in an example, with show commands to follow. Enjoy!


Chapter Examples and .PKT File Reference

Download this ZIP file to get all the .pkt files for this chapter: 

This table tells you what files to expect in the ZIP, and which examples happen to use interface IDs that can be exactly replicated in PT:


Example Topology File Initial Config Ending Config Exact Match of Interface IDs?
8-1 Yes Yes Yes Yes
8-2 Use 8-1 Use 8-1 ending Yes Yes
8-3 Use 8-1 Use 8-2 ending Yes Yes
8-4 Use 8-1 Yes None Yes
8-5 Use 8-1 Use 8-4 None Yes
8-6 Use 8-1 Use 8-4 None Yes
8-7 Use 8-1 Use 8-4 None Yes
8-8 Use 8-1 Yes Yes Yes
8-9 Use 8-1 Use 8-8 Use 8-8 Yes
8-10 Use 8-1 Use 8-4 Yes (A and B) Yes
8-11 Use 8-1 Use 8-4 Use 8-10 A Yes
8-12 Yes Yes Yes Yes
8-13 Use 8-12 Use 8-12 ending Yes Yes
8-14 Use 8-12 Use 8-13 ending Yes Yes
8-15 Use 8-12 Use 8-14 ending None Yes
8-16 Use 8-12 Use 8-14 ending None Yes
8-17 Use 8-12 Use 8-14 ending None Yes
8-18 None None None N/A
8-19 None None None N/A
8-20 Use 8-12 Yes Yes Yes
8-21 Use 8-12 Use 8-20 Use 8-20 Yes
8-22 Use 8-12 Use 8-20 Use 8-20 Yes


Reminders: Purpose of Each Type of .PKT File

Topology File: The file contains all devices and cables in the associated figure along with any implied extra devices. The purpose: you never had to add a device or cable. It also contains a few configuration commands that do not affect the example, but help you navigate, for instance, it sets hostnames, passwords (always “cisco”), and interface descriptions.

Initial Config: The file contains everything in the Topology file, plus all configuration listed or implied by the words and figures leading up to the example. That is, it attempts to match the state of the network just before the first line of the example.

Ending Config: The file adds the configuration listed in the example to the Initial Config file – nothing more, nothing less.


Table Lists “None” or Other Strange Terms?

Some examples have all three types of PKT files, however, some Examples have no PT files, and some have a mix of fewer than three files. Here’s a reminder of why. You can check this earlier post for more background if you care to know more.

Initial Config as “None”: If the table says “yes” for the Topology and Ending config, but not the Initial config, then the Topology file has all configuration needed at the beginning of the example.

Ending Config as “None”: The Ending config will be shown as “None” when the example as printed in the book does not have any configuration commands.

All Three Files as “None”:  We do not supply .pkt files for that example.

Use x-y:  Use Example x-y’s ending config file because the example continues earlier example x-y.


Tips and Exceptions

This section lists our comments about using PT to do the examples. When we built the files, when we saw any behavior that we thought might make it more difficult to perform the example, we noted that fact so we could list it here, in case it might help you with the examples.


Example 8-1

Note that the book does not provide any detail about the switches at the top of Figure 8-2 (on which examples 8-1, 8-2, and 8-3 are based.) However, the routers need to use VLAN trunking (ROAS) for VLANs 341 and 342, so the link between the switches must be a trunk. So, the Init file for these examples pre-configures trunking on the links between the switches (switchport mode trunk on each end.)


Examples 8-1, 8-2, and 8-3

While the book lists these as three separate examples, they each show configuration on different devices as part of one larger configuration sequence. You can just start with the files for Example 8-1 and work all the way through Example 8-3.

Also, note that the figures shows four routers (R1, R2, R3, and R4), while the examples show how to configure OSPF on R1, R2, and R3 only, with no mention of R4. To make the lab work to match the book, we pre-configured OSPF on R4 in the Init file. (If you start with the Topo file, make sure to configure OSPF on R4.)


Example 8-4

The book content makes working through the labs in this chapter a little difficult just due to some sequencing, particularly with Example 8-4. The Example shows output that relies on the configuration in the earlier examples, plus some other configuration not discussed so far. That additional configuration includes:


Examples 8-5, 8-6, 8-7

All three examples list show command output based on the same configuration and scenario of Example 8-4.


Example 8-8

Again, the navigation between examples in the book, as compared to repeating the labs in PT, requires some extra steps. This example an be challenging. This example shows the configuration added before the output in Examples 8-4, 8-5, 8-6, and 8-7 were collected. So that you can see the effects of the configuration process, the supplied Init PT file does not include the configuration commands listed in Example 8-8, leaving those for you to configure.


Example 8-9

This example lists show command output based on the ending configuration from Example 8-8.


Example 8-10

This example lists two methods to configure passive interfaces on a router, so we supply an “A” and “B” ending config file to match.


Example 8-11

This example lists show command output based on the “A” ending configuration from Example 8-10.


Example 8-12

This example begins a new topology to be configured, the Examples 8-13 and 8-14 listing output based on the ending configuration in Example 8-12.


Example 8-13

This example builds on 8-12 and uses 8-12 ending as the init file.


Example 8-14

This example builds on Example 8-13 and will use 8-13 ending as the init file. The final file, 8-14 ending completes the configuration of the topology.


Examples 8-15, 8-16, 8-17

This example is show commands based on 8-14 ending


Examples 8-18, 8-19

We did not supply files because PT (when testing) did not support the OSPF default-information originate always command (used in Example 8-18). Example 8-19 shows output dependent on Example 8-18’s configuration.


Example 8-20

This example asks you to migrate from OSPF configuration using the network OSPF subcommand to instead use OSPF ip ospf interface subcommands. The example shows the new configuration commands, but it does not show how to remove the old configuration. So, to perform this Example in PT, remove the old configuration in configuration mode by:

  1. Enter OSPF configuration mode using the router ospf 1 or similar command to enter OSPF configuration mode.
  2. Issue the no network network-id area area-id subcommand for each existing network command.


Example 8-21, 8-22

Both examples list show command output related to Example 8-20’s configuration, focusing on output that is different when a router uses OSPF interface configuration. However, PT does not list the correct output. So, you can use the ending config files for Example 8-20, and issue the show commands listed in these two examples, but in PT 7.2 we used in testing, you will not see the correct output. In particular:

Example 8-21: show ip protocols does not list the heading “Routing on Interfaces Configured Explicitly.”

Example 8-22: show ip ospf interface g0/0 does not list the phrase “Attached via Interface Enable” or “Attached via Network Statement.”


Ping and Traceroute: Cert Guide PT Labs for ICND1 Chapter 23
By certskills September 2, 2019 09:05
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  1. Mofajjel Hossain Shohag October 14, 14:39

    It helps me a lot to understand OSPF routing protocol.

    Reply to this comment
  2. Tim October 24, 18:39

    Tried to use the .pkt files and got error that files are not compatible with this version of packet tracer. I have the latest version of PT should I downgrade or can you provide a new version of the files? Sorry to have to ask…

    Reply to this comment
    • certskills Author October 28, 09:29

      Hey Tim,
      We’ve been using PT 7.2.1 for all the PT files. It’s my understanding that the compatibility rules are:
      Newer PT code should open/use old PT files.
      Old PT code won’t open files created w/ newer PT code.

      What version are you using, and what messages do you get? Let me know, and maybe we’ll figure it out.

      Reply to this comment
    • Tim October 29, 15:19

      Invalid File — Packet Tracer
      The file C:/Users/Tim/Documents/Packet Tracer Files/I2-Ex-8-8-ending.pkt is not compatible with this version of Packet Tracer.
      I see now that I have PT, Sorry about that, I am looking and I do not see a update option in the PT menus so I must have to download the latest version. Thanks again for all that you do, your thoroughness and knowledge have been very helpful.

      Reply to this comment
  3. kutay November 2, 04:53

    Dear Wendell,

    At example 8-8, configuring a Loopback interface on R2 to make the router use the loopback interface address as ist RID doesn’t work even after “clear ip ospf process”.
    However it works when manually configured with the “router-id” command.


    Reply to this comment
    • certskills Author November 5, 15:25

      thanks for the detail – much appreciated. Actually, what you’re seeing is correct as compared to real gear. I think either should have explained in more detail in the book, or at least mentioned that the “clear ip ospf process” updates the RID only in some circumstances. The combination of events that lead to “clear ip ospf process” resulting in a new RID is probably just too much about trivia to bother to list every detail. Anyway, note that a “copy run start” and “reload” does the trick in packet tracer! 🙂 Thanks,

      Reply to this comment
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