I am always reviewing Routing topics to have them all the time fresh in my mind, especially when I don’t practice with them a lot during daily works. This time I decided to refresh my knowledge about OSPF Areas and OSPF LSA types. To do that I prepared a very simple laboratory topology using GNS3 and its support to IOU images. The goal of the lab is to configure the routers and check what changes in the routing table and in the OSPF database when you change the areas attributes.
The Lab is already pre-configured with basic commands so you will not need to start from scratch and you can directly practice with commands and outputs. You can download it here. I am going to give you the steps you need to take to test your knowledge and get familiar with the topic.
- PRACTICE LAB – Step 1
– interfaces IPs are already configured for you.
– configure OSPF on all routers to achieve full convergence. Don’t activate OSPF on loopback interfacesof any router and configure on router “ASBR” the router-id to have it matching the loopback0.
– What OSPF LSA types you expect to see on ASBR and TEST-RTR?
– What kind of OSPF routes you expect to see on ASBR and TEST-RTR?
– What OSPF LSA types you expect to see on ABR1 and ABR2?
- PRACTICE LAB – Step 2 – Configure ASBR router to act as OSPF ASBR.
– configure ASBR router so that he will become indeed ASBR router. What you need to do for that?
– What LSA types you expect to see on ASBR, ABR1, ABR2 and TEST-RTR?
– What OSPF routes types will you see on TEST-RTR?
- PRACTICE LAB – Step 3 – Changing AREA 2 type to STUBBY
– configure OSPF area 2 as stub.
– What OSPF LSA types you expect to see on TEST-RTR?
– What OSPF routes type you expect to see on TEST-RTR?
- PRACTICE LAB – Step 4 – Change AREA 2 type to TOTALLY STUBBY.
– configure OSPF area 2 as Totlly Stubby.
– What OSPF LSA types you expect to see on TEST-RTR and ABR2?
– What OSPF routes type you expect to see on TEST-RTR and ABR2?
- PRACTICE LAB – Step 5 – Change AREA 1 to NSSA
– what steps do you need to have area 1 as NSSA and why do you want to have such type of area.
– configure OSPF Area 1 as NSSA.
– What OSPF LSA Types you expect to see on ASBR, ABR1 and ABR2?
– What OSPF routes type you expect to see on all routers?
– as last step revert the configuration of AREA 2 to act as a normal area and check what OSPF routes you see.
What you did with this lab should be quite helpful to test your current knowledge of OSPF as well as you current knowledge of Cisco commands to configure and troubleshoot. Maybe in the near future I will also publish another article with the solution to this lab.
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