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Forum Replies

  1. Here you can find the difference between the two:


    OSPF Totally NSSA

    LSA Type 8 and 9 are not used in OSPFv2 but I’ll explain these in OSPFv3.

  2. Hi Rajiv,

    OSPF is a link-state routing protocol but it only uses SPF within an area. A router in one area doesn’t know what the topology looks like from another area.

    Between areas, OSPF works similar to distance vector routing protocols like RIP or EIGRP. To ensure we have a loop-free topology, we have a hierarchical model. All areas have to be connected to the backbone and traffic from one area to another always has to go through the backbone area.

    Hope this helps.


  3. It has to do with the design of the network in question. The benefits you see of an area becoming a stub (reduced LSDB size) comes at a cost, which is the loss of some routing information details. This translates into routers within a stub not having all the information necessary to make the best possible choices.

    For example, suppose you have an area (which is non-zero, of course), that has multiple exit points. Now imagine that at each of those exit points there are separate external routing domains (say, EIGRP or BGP, etc). If this area is a stub, Type-5 LSAs are not allowed. This means that routers inside the stub won’t have the visibility to know the least cost path to get to external network X is through exit point 1, while getting to network Y, it is best to get through exit point 2.

  4. Thanks for making a video on this series. I am always thankful when I get to a video series as I read the book and website pages and just get worn out from studying 2-6 hours a day through the week. Not to mention on CCNP ROUTE I have taken to reading every single forum post as an added learning tool.

    Sometimes I just want to lean back in chair put on headset and listen to video as it allows me to relax a bit when tired towards end of day so uch thanks for those videos. Anyway great lesson!

    I am getting close to end of OSPF website lessons already finished the book lessons so woohoo on that!!! lol…

  5. Glad to hear you like it :slight_smile: Vimeo now also supports different playback speeds so you can set them to 1.5x or 2x if you like. I usually like videos when a topic is completely new to me or when I’m too tired to do anything else.

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