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CCNP Routing Studies: Basic Open Shortest Path First

Chapter Description

Understanding basic Open Shortest Path First (OSPF) routing principles not only applies to the CCNP certification but to all Cisco-based certifications. A concrete understanding of how OSPF routing works is fundamental for any small or large network. This chapter focuses on a number of objectives falling under the CCNP routing principles.

Review Questions

Use router output taken from R1 from the previous Practical Exercise to answer the following questions. Example 3-66 shows this sample output taken from R1 and includes the IP routing table and sample pings to area 1.

Example 3-66 R1's IP Routing Table and Ping Requests to Area 1

R1>show ip route

Gateway of last resort is not set

141.108.0.0/16 is variably subnetted, 8 subnets, 3 masks

O 141.108.1.128/25 [110/65] via 141.108.10.10, 00:15:28, Serial0/0

O 141.108.9.128/25 [110/129] via 141.108.10.10, 00:15:28, Serial0/0

O 141.108.1.0/25 [110/65] via 141.108.10.10, 00:15:28, Serial0/0

C 141.108.10.8/30 is directly connected, Serial0/0

O 141.108.9.0/25 [110/129] via 141.108.10.10, 00:15:28, Serial0/0

O IA 141.108.10.0/30 [110/192] via 141.108.10.10, 00:15:28, Serial0/0

O 141.108.12.0/24 [110/129] via 141.108.10.10, 00:15:28, Serial0/0

O 141.108.10.4/30 [110/128] via 141.108.10.10, 00:15:29, Serial0/0

131.108.0.0/16 is variably subnetted, 9 subnets, 4 masks

C 131.108.4.128/25 is directly connected, Loopback1

O 131.108.5.32/27 [110/1010] via 131.108.1.2, 00:16:04, Ethernet0/0

O 131.108.33.0/24 [110/74] via 141.108.10.10, 00:15:29, Serial0/0

O 131.108.6.1/32 [110/11] via 131.108.1.2, 00:16:04, Ethernet0/0

C 131.108.5.0/27 is directly connected, Loopback2

O 131.108.6.2/32 [110/11] via 131.108.1.2, 00:16:06, Ethernet0/0

C 131.108.4.0/25 is directly connected, Loopback0

C 131.108.1.0/24 is directly connected, Ethernet0/0

O 131.108.26.0/24 [110/138] via 141.108.10.10, 00:15:31, Serial0/0

R1#ping 131.108.4.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 131.108.4.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

R1#ping 131.108.4.129

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 131.108.4.129, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

R1#ping 131.108.5.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 131.108.5.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

R1#ping 131.108.5.33

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 131.108.5.33, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

R1#ping 131.108.6.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 131.108.6.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

R1#ping 131.108.6.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 131.108.6.2, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

R1#


View Example 3-66 to answer the following review questions.

The answers to these question can be found in Appendix C, "Answers to Review Questions."

  1. Which information is stored in an IP routing table as seen by R1?

  2. Which command do you use to view only OSPF routes?

  3. How many subnets are known by R1 using the Class B networks 131.108.0.0/16 and 141.108.0.0/16?

  4. What path is taken to the remote network 141.108.100.1/24?

  5. Why is the remote network 141.108.6.0/32 displayed as learned through the denotation: O IA?

  6. What is the cost associated with the remote network 131.108.33.0/24 [110/74]?