2.7.3 Packet Tracer – Multiarea OSPF Exploration – Physical Mode (Part 1) Answers

Last Updated on February 23, 2021 by Admin

2.7.3 Packet Tracer – Multiarea OSPF Exploration – Physical Mode (Part 1) Answers

Packet Tracer – Multiarea OSPF Exploration – Physical Mode (Part 1) (Answers Version)

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

Objectives

Part 1: Evaluate Network Operation of SingleArea OSPF

Part 2: Evaluate Network Operation of Multiarea OSPF

Part 3: Configure a New Area and Attach to Area 0 Through the Internet

Topology

Background / Scenario

Part 1: The Beginning

Casual Recording Company (CRC), based in Sao Paulo, Brazil, provides self-serve, mini-recording studios around the city so that anyone can rent a timeslot and record their songs by themselves. CRC began with a singlearea OSPF network located in one building. This idea was very popular and consequently the business has grown, causing the company to expand into a branch office in a second building at the far end of the city. They continued to use single-area OSPF.You will evaluate the impact of the expanded network.

Part 2: Business is Booming

The IT department in CRC decided to migrate to a multiarea OSPF network. You will evaluate the impact and benefits derived from the change to determine if it was a good decision or not.

Part 3: CRC Expansion Continues

CRC has continued to grow and will open a new branch office in Montevideo, Uruguay. You will configure the Area Border Router for the new area and physically connect the branch office network to the corporate headquarters network through the internet.

Instructions

Part 1:Evaluate Single-Area OSPF Network Operation

In this part, CRC has expanded to a second location in Sao Paulo and currently uses singlearea OSPF routing.

Step 1:Explore OSPF in the Corporate Headquarters.

  1. Click the city icon for Sao Paulo. Notice that there are two buildings connected by a fiber link.
  2. Click Corporate HQ, and then click the rack icon that represents the Sao Paulo HQ Wiring Closet.
  3. Click B1_R4, and then select the CLI tab.
  4. The terminal should show that G0/0/0 and G0/0/1 are up and that four adjacencies have been established, as shown below. If not, wait for the OSPF loading process to complete.

<output omitted>

Press RETURN to get started!

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0/0, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0/1, changed state to up

23:00:45: %OSPF-5-ADJCHG: Process 1, Nbr 172.17.1.1 on GigabitEthernet0/0/1 from LOADING to FULL, Loading Done

23:00:45: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.2.1 on GigabitEthernet0/0/0 from LOADING to FULL, Loading Done

23:00:45: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.1.1 on GigabitEthernet0/0/0 from LOADING to FULL, Loading Done

23:00:45: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.3.1 on GigabitEthernet0/0/0 from LOADING to FULL, Loading Done

B1_R4>

  1. Execute the show ip route command. Notice the size of the routing table and the routes learned via OSPF from the routers in the Sao Paulo Branch Office.

B1_R4> show ip route

Codes: L – local, C – connected, S – static, R – RIP, M – mobile, B – BGP

D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area

N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2

E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP

i – IS-IS, L1 – IS-IS level-1, L2 – IS-IS level-2, ia – IS-IS inter area

* – candidate default, U – per-user static route, o – ODR

P – periodic downloaded static route

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 11 subnets, 3 masks

O10.10.0.0/30 [110/3] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.10.0.4/30 [110/4] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.10.0.8/30 [110/4] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.10.0.12/30 [110/5] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.10.0.16/30 [110/5] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.10.0.20/30 [110/4] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.20.0.1/32 [110/5] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.20.1.1/32 [110/5] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.20.2.1/32 [110/5] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.20.3.1/32 [110/5] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

O10.20.4.0/24 [110/5] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

172.17.0.0/30 is subnetted, 1 subnets

O172.17.1.0/30 [110/2] via 192.168.0.10, 00:05:09, GigabitEthernet0/0/1

192.168.0.0/24 is variably subnetted, 4 subnets, 2 masks

C192.168.0.0/29 is directly connected, GigabitEthernet0/0/0

L192.168.0.4/32 is directly connected, GigabitEthernet0/0/0

C192.168.0.8/29 is directly connected, GigabitEthernet0/0/1

L192.168.0.9/32 is directly connected, GigabitEthernet0/0/1

O192.168.1.0/24 [110/2] via 192.168.0.1, 00:05:09, GigabitEthernet0/0/0

192.168.2.0/32 is subnetted, 1 subnets

O192.168.2.1/32 [110/2] via 192.168.0.2, 00:05:09, GigabitEthernet0/0/0

192.168.3.0/32 is subnetted, 1 subnets

O192.168.3.1/32 [110/2] via 192.168.0.3, 00:05:09, GigabitEthernet0/0/0

  1. On B1_R4, execute the show ip ospf command.

B1_R4> show ip ospf

Routing Process “ospf 1” with ID 192.168.0.9

Supports only single TOS(TOS0) routes

Supports opaque LSA

SPF schedule delay 5 secs, Hold time between two SPFs 10 secs

Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs

Number of external LSA 0. Checksum Sum 0x000000

Number of opaque AS LSA 0. Checksum Sum 0x000000

Number of DCbitless external and opaque AS LSA 0

Number of DoNotAge external and opaque AS LSA 0

Number of areas in this router is 1. 1 normal 0 stub 0 nssa

External flood list length 0

Area BACKBONE(0)

Number of interfaces in this area is 2

Area has no authentication

SPF algorithm executed 3 times

Area ranges are

Number of LSA 19. Checksum Sum 0x078182

Number of opaque link LSA 0. Checksum Sum 0x000000

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 0

Flood list length 0

Questions:

Record the number of times that the SPF algorithm has been executed.

Type your answer here.

In Packet Tracer, answers will vary.

How many areas are displayed on router B1_R4?

Type your answer here.

One area, Area 0 is displayed

  1. Keep the console window for B1_R4 open. Click B1_R2, and then select the CLI tab. Execute the same two commands.

B1_R2> show ip route

Codes: L – local, C – connected, S – static, R – RIP, M – mobile, B – BGP

D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area

N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2

E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP

i – IS-IS, L1 – IS-IS level-1, L2 – IS-IS level-2, ia – IS-IS inter area

* – candidate default, U – per-user static route, o – ODR

P – periodic downloaded static route

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 11 subnets, 3 masks

O10.10.0.0/30 [110/4] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.10.0.4/30 [110/5] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.10.0.8/30 [110/5] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.10.0.12/30 [110/6] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.10.0.16/30 [110/6] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.10.0.20/30 [110/5] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.20.0.1/32 [110/6] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.20.1.1/32 [110/6] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.20.2.1/32 [110/6] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.20.3.1/32 [110/6] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O10.20.4.0/24 [110/6] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

172.17.0.0/30 is subnetted, 1 subnets

O172.17.1.0/30 [110/3] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

192.168.0.0/24 is variably subnetted, 3 subnets, 2 masks

C192.168.0.0/29 is directly connected, GigabitEthernet0/0/0

L192.168.0.2/32 is directly connected, GigabitEthernet0/0/0

O192.168.0.8/29 [110/2] via 192.168.0.4, 00:04:44, GigabitEthernet0/0/0

O192.168.1.0/24 [110/2] via 192.168.0.1, 00:04:44, GigabitEthernet0/0/0

192.168.2.0/24 is variably subnetted, 2 subnets, 2 masks

C192.168.2.0/24 is directly connected, Loopback0

L192.168.2.1/32 is directly connected, Loopback0

192.168.3.0/32 is subnetted, 1 subnets

O192.168.3.1/32 [110/2] via 192.168.0.3, 00:04:44, GigabitEthernet0/0/0

B1_R2> show ip ospf

Routing Process “ospf 1” with ID 192.168.2.1

Supports only single TOS(TOS0) routes

Supports opaque LSA

SPF schedule delay 5 secs, Hold time between two SPFs 10 secs

Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs

Number of external LSA 0. Checksum Sum 0x000000

Number of opaque AS LSA 0. Checksum Sum 0x000000

Number of DCbitless external and opaque AS LSA 0

Number of DoNotAge external and opaque AS LSA 0

Number of areas in this router is 1. 1 normal 0 stub 0 nssa

External flood list length 0

Area BACKBONE(0)

Number of interfaces in this area is 2

Area has no authentication

SPF algorithm executed 2 times

Area ranges are

Number of LSA 19. Checksum Sum 0x078291

Number of opaque link LSA 0. Checksum Sum 0x000000

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 0

Flood list length 0

For the show ip route command, compare the output of B1_R2 to the output of B1_R4. Notice that the B1_R2 routing table, with the exception of local and connected routes, has learned the same routes via OSPF as B1_R4.

Question:

Record the number of times that the SPF algorithm has been executed.

Type your answer here.

In Packet Tracer, answers will vary.

Step 2:Explore OSPF in the Branch Office.

  1. Keep the console windows open for both routers B1_R2 and B1_R4.
  2. On the blue tool bar at the top, click the Back level button twice to return to the Sao Paulo city view. You can also use the shortcut keys Alt+Left arrow key.
  3. Click Branch Office, and then the rack icon that represents the Sao Paulo Branch Office Wiring Closet.
  4. Click B2_R3, and then select the CLI tab.
  5. The terminal should show that G1/0 and G2/0 are up and that two adjacencies have been established, as shown below.

<output omitted>

Press RETURN to get started!

%LINK-5-CHANGED: Interface GigabitEthernet1/0, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0, changed state to up

%LINK-5-CHANGED: Interface GigabitEthernet2/0, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0, changed state to up

23:00:40: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on GigabitEthernet2/0 from LOADING to FULL, Loading Done

23:00:45: %OSPF-5-ADJCHG: Process 1, Nbr 4.4.4.4 on GigabitEthernet1/0 from LOADING to FULL, Loading Done

B2_R3>

  1. Execute the show ip route command. Compare the output of B2_R3 to the output of B1_R4 or B1_R2. Notice that other than a few connected or local routes, the same networks are displayed.

B2_R3# show ip route

Codes: C – connected, S – static, I – IGRP, R – RIP, M – mobile, B – BGP

D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area

N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2

E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP

i – IS-IS, L1 – IS-IS level-1, L2 – IS-IS level-2, ia – IS-IS inter area

* – candidate default, U – per-user static route, o – ODR

P – periodic downloaded static route

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 11 subnets, 3 masks

O10.10.0.0/30 [110/2] via 10.10.0.5, 00:49:38, GigabitEthernet1/0

C10.10.0.4/30 is directly connected, GigabitEthernet1/0

O10.10.0.8/30 [110/2] via 10.10.0.5, 00:49:38, GigabitEthernet1/0

C10.10.0.12/30 is directly connected, GigabitEthernet2/0

O10.10.0.16/30 [110/2] via 10.10.0.14, 00:49:38, GigabitEthernet2/0

O10.10.0.20/30 [110/2] via 10.10.0.5, 00:49:28, GigabitEthernet1/0

[110/2] via 10.10.0.14, 00:49:28, GigabitEthernet2/0

O10.20.0.1/32 [110/2] via 10.10.0.14, 00:49:38, GigabitEthernet2/0

O10.20.1.1/32 [110/2] via 10.10.0.14, 00:49:38, GigabitEthernet2/0

O10.20.2.1/32 [110/2] via 10.10.0.14, 00:49:38, GigabitEthernet2/0

O10.20.3.1/32 [110/2] via 10.10.0.14, 00:49:38, GigabitEthernet2/0

O10.20.4.0/24 [110/2] via 10.10.0.14, 00:49:38, GigabitEthernet2/0

172.17.0.0/30 is subnetted, 1 subnets

O172.17.1.0 [110/3] via 10.10.0.5, 00:49:38, GigabitEthernet1/0

192.168.0.0/29 is subnetted, 2 subnets

O192.168.0.0 [110/5] via 10.10.0.5, 00:49:38, GigabitEthernet1/0

O192.168.0.8 [110/4] via 10.10.0.5, 00:49:38, GigabitEthernet1/0

O192.168.1.0/24 [110/6] via 10.10.0.5, 00:49:38, GigabitEthernet1/0

192.168.2.0/32 is subnetted, 1 subnets

O192.168.2.1 [110/6] via 10.10.0.5, 00:49:38, GigabitEthernet1/0

192.168.3.0/32 is subnetted, 1 subnets

O192.168.3.1 [110/6] via 10.10.0.5, 00:49:38, GigabitEthernet1/0

  1. On B2_R3, execute the show ip ospf command.

B2_R3# show ip ospf

Routing Process “ospf 1” with ID 3.3.3.3

Supports only single TOS(TOS0) routes

Supports opaque LSA

SPF schedule delay 5 secs, Hold time between two SPFs 10 secs

Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs

Number of external LSA 0. Checksum Sum 0x000000

Number of opaque AS LSA 0. Checksum Sum 0x000000

Number of DCbitless external and opaque AS LSA 0

Number of DoNotAge external and opaque AS LSA 0

Number of areas in this router is 1. 1 normal 0 stub 0 nssa

External flood list length 0

Area BACKBONE(0)

Number of interfaces in this area is 2

Area has no authentication

SPF algorithm executed 4 times

Area ranges are

Number of LSA 19. Checksum Sum 0x0624fb

Number of opaque link LSA 0. Checksum Sum 0x000000

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 0

Flood list length 0

Questions:

Record the number of times that the SPF algorithm has been executed.

Type your answer here.

In Packet Tracer, answers will vary.

How many areas are displayed on router B2_R3?

Type your answer here.

One area, Area 0 is displayed

  1. Keep the console window open. Click B2_R1, and then select the CLI tab. The output should be similar to the output of B2_R3.

B2_R1> show ip route

Codes: C – connected, S – static, I – IGRP, R – RIP, M – mobile, B – BGP

D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area

N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2

E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP

i – IS-IS, L1 – IS-IS level-1, L2 – IS-IS level-2, ia – IS-IS inter area

* – candidate default, U – per-user static route, o – ODR

P – periodic downloaded static route

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 11 subnets, 3 masks

O10.10.0.0/30 [110/2] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

O10.10.0.4/30 [110/2] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

C10.10.0.8/30 is directly connected, GigabitEthernet1/0

O10.10.0.12/30 [110/2] via 10.10.0.18, 00:55:32, GigabitEthernet2/0

C10.10.0.16/30 is directly connected, GigabitEthernet2/0

O10.10.0.20/30 [110/2] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

[110/2] via 10.10.0.18, 00:55:32, GigabitEthernet2/0

O10.20.0.1/32 [110/2] via 10.10.0.18, 00:55:32, GigabitEthernet2/0

O10.20.1.1/32 [110/2] via 10.10.0.18, 00:55:32, GigabitEthernet2/0

O10.20.2.1/32 [110/2] via 10.10.0.18, 00:55:32, GigabitEthernet2/0

O10.20.3.1/32 [110/2] via 10.10.0.18, 00:55:32, GigabitEthernet2/0

O10.20.4.0/24 [110/2] via 10.10.0.18, 00:55:32, GigabitEthernet2/0

172.17.0.0/30 is subnetted, 1 subnets

O172.17.1.0 [110/3] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

192.168.0.0/29 is subnetted, 2 subnets

O192.168.0.0 [110/5] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

O192.168.0.8 [110/4] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

O192.168.1.0/24 [110/6] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

192.168.2.0/32 is subnetted, 1 subnets

O192.168.2.1 [110/6] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

192.168.3.0/32 is subnetted, 1 subnets

O192.168.3.1 [110/6] via 10.10.0.9, 00:55:32, GigabitEthernet1/0

B2_R1> show ip ospf

Routing Process “ospf 1” with ID 1.1.1.1

Supports only single TOS(TOS0) routes

Supports opaque LSA

SPF schedule delay 5 secs, Hold time between two SPFs 10 secs

Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs

Number of external LSA 0. Checksum Sum 0x000000

Number of opaque AS LSA 0. Checksum Sum 0x000000

Number of DCbitless external and opaque AS LSA 0

Number of DoNotAge external and opaque AS LSA 0

Number of areas in this router is 1. 1 normal 0 stub 0 nssa

External flood list length 0

Area BACKBONE(0)

Number of interfaces in this area is 2

Area has no authentication

SPF algorithm executed 3 times

Area ranges are

Number of LSA 19. Checksum Sum 0x0624fb

Number of opaque link LSA 0. Checksum Sum 0x000000

Number of DCbitless LSA 0

Number of indication LSA 0

Number of DoNotAge LSA 0

Flood list length 0

  1. On B2_R1, click Physical tab and power the device off to simulate a power outage. Networks 10.10.0.8/30 and 10.10.0.16/36 will no longer be advertised.
  2. Issue the show ip route and the show ip ospf commands on one router in the Branch office and one router in the Head Office.

Question:

Are the two networks missing from both of the routing tables and have the SPF algorithm executions increased?

Type your answers here.

Yes for both questions.

Note: Every router, in both buildings, has been forced to do extra SPF algorithm executions. Because all of the routers are in the same area, every change to the topology will cause OSPF to execute the SPF algorithm on each router. This is not a problem for small networks, but for large networks, excessive SPF calculations can impact network performance. The solution is to divide the OSPF topology into multiple areas. Changes in topology in one area will not cause SPF recalculations in other areas.

You have completed Part 1: Evaluate Network Operation of SingleArea OSPF.

To continue to Part 2: Evaluate Multiarea OSPF Network Operation, close this Packet Tracer file. Return to the online course and open the Multiarea OSPF Exploration – Physical Mode (Part2) Packet Tracer file.

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