What is the difference between nssa and totally nssa

You can use the NSSA not-so-stubby-area. This is the same thing as the stub area with the exception that you are allowed to have an ASBR within the area. How does it work? This is where the type 7 external LSA kicks in. What about totally stub? Anything else you need to know? If you like to keep on reading, Become a Member Now! Here is why:. Notice that the inter-area LSA 3 entries are now also removed. The show ospf database output below only shows intra-area LSA 1 and 2 and a 0.

The default route is now used to reach any inter-area or external route destinations. Lets have a look at the configuration for a NSSA area. The command to inject a default route into the area is slightly different as it also requires the default-lsa keyword. The effect of the NSSA area configuration is clear from the show ospf database output.

Alternatively if the metric is the same even load sharing can be accomplished. The output of the show ospf database command shows that inter-area routes LSA 3 also have been blocked and that local redistribution is still possible via type 7 LSAs.

The default route injection is now again done as a Summary LSA 3. Therefore it should point towards an ABR as otherwise the inter-area routes might become unreachable. This should never be needed anymore as it was needed for interoperability with Junos versions 5 or earlier. So the command set protocols ospf area 10 nssa default-lsa type 7 is obsolete in modern Junos networks.

The ABR will convert these type 7 external routes into type 5 external routes. During this conversion you can choose to summarize or filter these prefixes into the non-NSSA areas as discussed in an earlier post.

The output of show ospf database on R2 normal area shows the What if we enable redistribution on the ABR itself. Notice the On R10 the It is possible to change this default behavior on the ABR R1 by using the set protocols ospf no-nssa-abr command. Both configuration options and database analysis have been discussed for each of the 4 different area types.

For JNCIE candidates it is important to understand all these area types as they are fair game on any written or lab exam. For production network use I would strongly advise not to use the stub or totally stub variants. More Posts. Hi Willy, It was a great post. At this point, one thing is not clear for me. Its a nice document. Could you check the attachement.

R3 area 10 nssa default-information-originate On R4 the default-route to R3 appears after to apply the followings commands on R3 and R4 R3 area 10 nssa no-summary R4 area 10 nssa Thanks in advance for your reply, Hoping to have been clear.

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