Area 1 possibly needs to know about the prefixes in those areas — but not the topology. This seems excessive! Type 5 LSAs are empty calories to me. This is literally what they say. And, as you might have guessed by now, all we had to do to filter out these Type 5 LSAs was to configure Area 1 as a stub area.
Like a lot of things in networking, the theory involves a lot of reading — but the actual configuration is one single line of config. Do you remember we talked about those a moment ago? Well, in our topology, yes! So, now you know all about the behind-the-scenes mechanics, we can finally give a more accurate definition of a stub area:.
Yep: that is their genuine name, because OSPF is absolutely ridiculous. Looking one final time at our topology, imagine that Area 2 was also a stub area.
Then, when Router 3 re-advertises them from Area 2 to Area 0, it converts them from Type 7 to Type 5. If you enjoyed this post and you want to find out when I write more, follow me on Twitter! Or, if you prefer follow me on LinkedIn.
The choice is very much yours. Thank you so much for reading! Unbelively fun, clear and to the point content!! Digging your site now : thanks for being you Chris!!! Great stuff Chris. Really networking books made it so confusing Now Finally,I got the clear view on this topic.
Thank you so much. Your email address will not be published. December 6, May 1, Chris Views 7 Comments. The answer to that question depends on a lot of factors. There are lots of different kinds of LSA, and each one serves a different purpose. But what definitely should happen is that the relevant prefixes need to disappear from Area 1. Woah — every single OSPF route is gone!
Is that really correct? To confirm your OSPFv3 configuration, enter the show protocols ospf3 command. Verify that the interface for OSPF has been configured for the appropriate area. Verify that the OSPF area is a stub area. Confirm that the output displays Normal Stub as the Stub type. The backbone area, which is 0 in Figure 3 , has a special function and is always assigned the area ID 0.
Area IDs need only be unique within an AS. All other networks or areas such as 3, 7, and 9 in the AS must be directly connected to the backbone area by ABRs that have interfaces in more than one area. An OSPF stub area has no external routes, so you cannot redistribute routes from another protocol into a stub area. You configure each routing device in area 9 area ID 0. The second example also shows the optional configuration required to disable exporting Type 7 LSAs into the NSSA by including the no-nssa-abr statement on the routing device that performs the functions of both an ABR and an AS boundary router.
You must configure all routing devices that are part of the NSSA. Configuration on the ABR. The output also includes the optional metric-type and type-7 statements. To quickly disable exporting Type 7 LSAs into the NSSA, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the [edit] hierarchy level, and then enter commit from configuration mode.
Confirm that the output displays Not so Stubby Stub as the Stub type. Verify the type of LSAs that are in the area. All rights reserved. Help us improve your experience. Let us know what you think. Do you have time for a two-minute survey?
Maybe Later. Generally these area types are confused by the new network engieers. These area types are prevent some routes to enter the Area routers.
We will check all of these one by one. For this article, the below topology will be our reference topology. They also do not accept Type 4 LSAs.
To configure an area as a Stub Area, we need to configure all the routers in this area as Stub. Because, configuring a router interface as a Stub, changes the option bits in the Hello Packets.
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