2.6.6 Packet Tracer – Verify Single-Area OSPFv2 Answers

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Answers Note: Red font color or gray highlights indicate text that appears in the instructor copy only.

Addressing Table

Objectives

In this lab, you will use the CLI commands to verify the operation of an existing OSPFv2 network. In Part 2, you will add a new LAN to the configuration and verify connectivity.

• Identify and verify the status of OSPF neighbors.
• Determine how the routes are being learned in the network.
• Explain how the neighbor state is determined.
• Examine the settings for the OSPF process ID.
• Add a new LAN into an existing OSPF network and verify connectivity.

Background / Scenario

You are the network administrator for a branch office of a larger organization.  Your branch is adding a new wireless network into an existing branch office LAN. The existing network is configured to exchange routes using OSPFv2 in a single-area configuration.  Your task is to verify the operation of the existing OSPFv2 network, before adding in the new LAN. When you are sure that the current OSPFv2 LAN is operating correctly, you will connect the new LAN and verify that OSPF routes are being propagated for the new LAN. As branch office network administrator, you have full access to the IOS on routers R3 and R4. You only have read access to the enterprise LAN routers R1 and R2, using the username BranchAdmin, and the password Branch1234.

Answers Note: The username Admin, password Cisco1234 has full privilege level 15 on routers R1 and R2.

Instructions

Part 1:  Verify the existing OSPFv2 network operation.

The following commands will help you find the information needed to answer the questions:

show ip interface brief

show ip route

show ip route ospf

show ip ospf neighbor

show ip protocols

show ip ospf

show ip ospf interface

Step 1:  Verify OSPFv2 operation.

Wait until STP has converged on the network. You can click the Packet Tracer Fast Forward Time button to speed up the process. Continue only when all link lights are green.

1. Log into router R1 using the username BranchAdmin and the password Branch1234. Execute the show ip route command.

Open configuration window

R1# show ip route

— output omitted —-

Gateway of last resort is 172.16.3.2 to network 0.0.0.0

     172.16.0.0/16 is variably subnetted, 5 subnets, 3 masks

C       172.16.1.0/24 is directly connected, GigabitEthernet0/0

L       172.16.1.1/32 is directly connected, GigabitEthernet0/0

O       172.16.2.0/24 [110/65] via 172.16.3.2, 00:02:18, Serial0/0/0

C       172.16.3.0/30 is directly connected, Serial0/0/0

L       172.16.3.1/32 is directly connected, Serial0/0/0

O    192.168.1.0/24 [110/65] via 192.168.10.6, 00:02:18, Serial0/0/1

     192.168.10.0/24 is variably subnetted, 3 subnets, 2 masks

C       192.168.10.4/30 is directly connected, Serial0/0/1

L       192.168.10.5/32 is directly connected, Serial0/0/1

O       192.168.10.8/30 [110/128] via 172.16.3.2, 00:02:18, Serial0/0/0

                        [110/128] via 192.168.10.6, 00:02:18, Serial0/0/1

O*E2 0.0.0.0/0 [110/1] via 172.16.3.2, 00:02:18, Serial0/0/0

Questions:

How did router R1 receive the default route?

Type your answers here.

The default route was learned through OSPF.

From which router did R1 receive the default route?

Type your answers here.

Router R2

How can you filter the output of show ip route to show only the routes learned through OSPF?

Type your answers here.

Use either show ip route ospf or show ip route | include O

2. Execute the show ip ospf neighbor command on R1.

Questions:

Which routers have formed adjacencies with router R1?

Type your answers here.

R2 and R3

What are the router IDs and state of the routers shown in the command output?

Type your answers here.

2.2.2.2 – Full/–  and 3.3.3.3 – Full/-

Are all of the adjacent routers shown in the output?

Type your answers here.

Yes

3. Using the command prompt on PC1, ping the address of the ISP Router shown in the Address Table. Is it successful? If not, do a clear ospf process command on the routers and repeat the ping command.

Step 2:  Verify OSPFv2 operation on R2.

1. Log into router R2 using the username BranchAdmin and the password Branch1234. Execute the show ip route command. Verify that routes to all the networks in the topology are shown in the routing table.

Question:

How did router R2 learn the default route to the ISP?

Type your answers here.

It was statically configured by the administrator.

2. Enter the show ip ospf interface g0/0 on router R2.

Questions:

What type of OSPF network is attached to this interface?

Type you answers here.

BROADCAST

Are OSPF hello packets being sent out this interface? Explain.

Type your answers here.

No. The interface is configured as a passive interface in OSPF.

3. Using the command prompt on PC2, ping the S0/0/1 address on router R3.

Question:

Is it successful?

Type your answers here.

Yes

Step 3:  Verify OSPFv2 operation on R3.

1. Execute the show ip protocols command on router R3.

Question:

Router R3 is routing for which networks?

Type your answers here.

192.168.1.0/24, 192.168.10.4/30, and 192.168.10.8/30

2. Execute the show ip ospf neighbor detail command on router R3.

Question:

What is the neighbor priority shown for the OSPF neighbor routers? This value is the default.

Type your answers here.

0

3. Using the command prompt on PC3, ping the address of the ISP Router shown in the Address Table.

Question:

Is it successful?

Type your answers here.

Yes

Close configuration window

Part 2:  Add the new Branch Office LAN to the OSPFv2 network.

You will now add the pre-configured Branch Office LAN to the OSPFv2 network.

Step 1:  Verify the OSPFv2 configuration on router R4.

Open configuration window

Execute a show run | begin router ospf command on router R4. Verify that the network statements are present for the networks that are configured on the router.

Which interface is configured to not send OSPF update packets?

Type your answers here.

Interface GigabitEtherenet0/0/1

Step 2:  Connect the Branch Office router R4 to the OSPFv2 network.

1. Using the correct Ethernet cable, connect the G0/0/0 interface on router R4 to the G0/1 interface on switch S3. Use the show ip ospf neighbor command to verify that router R4 is now adjacent with router R3.

Question:

What state is displayed for router R3?

Type your answers here.

FULL/DR

2. Using the show ip ospf neighbor command on R3, determine the state of router R4. There may be a delay while OSPF converges.

Question:

Why is the state of router R4 different than the state of R1 and R2?

Type your answers here.

Because the OSPF network type between R1 and R2 is Point-to-Point, there is no OSPF election. R4 is on the same Ethernet network segment as router R3, so the OSPF network type is Broadcast and there is an OSPF election. When more than one router is located on a multiaccess network segment, only one router, the DR, sends OSPFv2 updates. A second router, in this case R4, becomes the Backup Designated Router and can take over if the DR router fails.

3. Using the command prompt on Laptop, ping the address of PC2.

Question:

Is it successful?

Type your answers here.

Yes

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