OSPF NSSA Area LSA7-to-5 Translator Election

Previous | Intermediate Level | Next

Task 1

In the task 3 of the previous lab you configured R3 as the gateway for all inter-area prefixes. Remove this configuration making area 34 NSSA with both R3 and R4 injecting N2 default route.

Task 2
Ensure that R3 is the LSA7-to-5 Translator.

Questions

Try to answer the following questions:

1. In case there are two or more ABRs connected to the NSSA area, which device translates LSA7 to LSA5 while injecting NSSA external routes into OSPF area 0?

Lab Solution

Solution configuration can be accessed below; solution contains task 1 and task 2 (if you want to save it, click the link, then go to File-->Download):
https://drive.google.com/file/d/0BwE5C95tpjZOSDZzZGV0czdmak0/edit?usp=sharing

Task 1

In the task 3 of the previous you configured R3 as the gateway for all inter-area prefixes. Remove this configuration making area 34 NSSA with both R3 and R4 injecting N2 default route.

R4 Config:

!

router ospf 1
 no area 34 no-summary

 area 34 nssa default-information-originate

!

Note!

Both R3 and R4 have the same 'area 34 nssa default-information-originate' configured in the OSPF router.

Pic. 2 - R3 and R4 Inject N2 Default Route.

Task 2

Ensure that R3 is the LSA7-to-5 Translator.

Note!

In order to see which device is advertising 10.0.7.7/32 prefix, check 'show ip ospf database' on R1. Look at the output below:

Pic. 3 - LSA7-to-LSA5 Current Translator (now change in the config).

R3 Config:

Pic. 4 - R3 Configuration.

Note!

For this change to take effect, clear ip ospf process on R3 as per Pic. 3, but also clear ospf process on R1 before you check the below:

Pic. 5 - LSA7-to-LSA5 Current Translator.

Study Drill

The router with the highest router-id becomes LSA7-to-LSA5 translator. 

Previous | Intermediate Level | Next