OSPF Lab Idea

[deanwebb]

In Cisco Packet Tracer / VIRL / GNS3, set up 4 routers.

Connect A to B, B to C, C to D, and then D to A. Like a square. Or a trapezoid or parallelogram if you're bad with right angles. Nobody cares. We'll call these the core routers. Use IP addresses in the 192.168.0.0 ranges.

*How many VLANS do you need for the router-to-router connections?

*If you use OSPF, router IDs by default are determined by IP addresses of active interfaces. How can you set router IDs in a way that even if interfaces go down, the router ID remains constant?

Connect another router to A, B, C, and D. We'll call them A', B', C', and D', respectively. We'll add a bunch of routes to them in a minute. For now, use IP addresses in the 172.16.0.0/16 range for the connections between these routers and the core routers.

*What command can you use to add a static route?

On A', B', C', and D', set a default route to A, B, C, and D, respectively.

*What command can you use to add a default route? What traffic will use the default route?

On A', set static routes out interfaces not connected to A. Use IP addresses in the 10.1.0.0/16 range. Create at least 4.
On B', set static routes out interfaces not connected to B. Use IP addresses in the 10.2.0.0/16 range. Create at least 4.
On C', set static routes out interfaces not connected to C. Use IP addresses in the 10.3.0.0/16 range. Create at least 4.
On D', set static routes out interfaces not connected to A. Use IP addresses in the 10.4.0.0/16 range. Create at least 4.

Set each router to use OSPF.

*What do the routing tables on each router look like?
*What is route summarization? Do you see any of it happening in your environment?
*Does it make a difference in the routing tables if all the routes on a router go out the same interface instead of different interfaces?
*What will happen in this environment if a device tries to reach an IP address that is not in one of the ranges defined in the routing table? What can be done to remediate that situation?