Class Activity – Stepping Through OSPFv3 Instructions Answers Stepping Through OSPFv3 (Instructor Version)

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


Explain the process by which link-state routers learn about other networks.

This class activity is designed for groups of three students. Its objective is to review the shortest path first routing process.


This class activity is designed for groups of three students. The objective is to review the Shortest Path First (SPF) routing process.

You will design and address a network, communicate the network address scheme and operation of network links to your group members, and compute the SPF.

Complete the steps as shown on the PDF for this class activity. If you have time, share your network design and Open Shortest Path First (OSPF) process with another group.


In preparation of this activity, you will need two different IPv6 network and cost numbers. The IPv6 network numbers must be chosen with the following format: 2002:DB8:AAAA:?::0/64, where? is a student-selected network number. You have two choices for cost – 10 (Fast Ethernet network), or 1 (Gigabit Ethernet network).

Bring your two IPv6 network and cost numbers to the group setting. One student in your group will act as the recorder, will draw three circles, and connect them on paper. Each circle will represent a student’s router and the connecting lines will represent the networks and links to be agreed upon.

Each group member should follow Steps 1 to 4 (below) in the order listed. As the group progresses through the activity, you should keep personal notes about your own router, including information about neighbor adjacency, link-state advertisements, topology table entries, and the SPF algorithm.


Step 1:

a. Speak to the classmate to your left. Compare network and cost numbers brought to the group. Agree upon an IPv6 network, links, and cost numbers you would like to use between your two routers. Remember, you may only use 1 (Gigabit Ethernet) or 10 (Fast Ethernet) for cost. When you have agreed upon your network, link numbers, and determined the cost of the route, record the information on the paper graphic created by the recorder.

b. Complete the same process with the classmate to your right.

c. After speaking with both of your direct neighbors, you have agreed upon two networks with link addresses and the cost of the route. Record the information you agreed upon on the paper graphic.

Step 2:

a. Each student will speak only to their direct neighbors. They will share all of their IPv6 network and link numbers and the cost of the networks to which they are connected. Almost immediately, everyone in the group will know about all networks, their links, and the cost of the individual networks between neighbors.

b. Check with the group members to ascertain all group members have the same information with which to work for Step 3.

Step 3:

a. On your own paper, create a table listing possible paths to all other networks. Use the formula supplied with this chapter n(n – 1)/2. You will have a total of four possible routes to list on your table.

b. On the table created in the Step 3 a., add a column with the headings, IPv6 Network Number and Cost.

c. Fill in the table with information you know about the networks on your group’s topology.

Step 4:

a. Go back to the table created in Step 3.

b. Place a star by the lowest-cost routes to all other routers.

When these four steps are complete, you have established neighbor adjacencies, exchanged link-state advertisements, built a topology table, and created a routing table with the best cost to all other networks within your group or area.

If you have the time, refer to your topology table and build the network on real equipment or Packet Tracer. Use some or all of the commands listed below to prove OSPF’s operation:

R1# show ipv6 interface brief
R1# show ipv6 protocols
R1# show ip protocols
R1# show ipv6 route


1. Which OSPFv3 processing step is reviewed in Step 1 of this activity?
Step 1 reviews creating adjacencies with direct neighbors.

2. Which OSPFv3 processing step is reviewed in Step 2 of this activity?
Step 2 is a review of the OSPFv3 link state advertisement process.

3. Which process for OSPFv3 is reviewed in Step 3 of this activity?
Step 3 is a review of how to build a topology table for the entire network.

4. Which process step for OSPFv3 is reviewed in Step 4 of this activity?
Step 4 reviews using the SPF process for calculating the routing table entries.

Identify elements of the model that map to IT-related content:

  • Physical topology
  • OSPFv3 process and vertification commands
  • IPv6 network and link addressing
  • Cost
  • Neighbor adjacencies
  • Link state advertisements
  • Topology table
  • IPv6 routing table
  • OSPFv3 operation commands
Notify of

Inline Feedbacks
View all comments