OSPF again  Why OSPF is such important? Why do I care for this topic so much time?   Interesting questions, I do not really know. When I start to process a topic for my exam preparation I do not know how much time I have to learn it. But when I learn it, I feel the importance of the subject area.     If you would like to read more detailed information about OSPF I suggest that link: https://www.ciscopress.com/articles/article.asp?p=2294214&seqNum=4   So let me explain to you that what are the differences between OSPFv2 and OSPFv3? In a high level view the two protocols are only different in the Internet Protocol version support. OSPFv2 is only support IPv4. OSPFv3 support both AFs (address family), but If you wanna know some detail about the other differences you need research better this topic. 1. Network types In OSPFv2 there is 5 network type which is the same in OSPFv3 broadcast non broadcast point-to-point point-to-multipoint point-to-multipoint non broadcast  Ok these types

Hello there! I can not leave the OSPF subject because  it is too beautiful to abandon it. In this post I try to demonstrate how the LSAs work in different OSPF scenarios. In the last post I wrote what is the LSAs, which network type is available, and which router types are exist in an OSPF network. But I do not described these things. On this post I try to define these topics better.  To understand that LSAs how can be flooded on different areas you need to understand the area types. As I mentioned before, there is 5 type of area exist of OSPF. Basically in a backbone/regular area the following LSA types will be flooded: Type 1 Router LSA Type 2 Network LSA Type 3 ABR Summary LSA - if ABR exist in the area. Type 4 ASBR Network LSA - if ASBR exist in the area. Type 5 ASBR Summary LSA - if ASBR exist in the area.  Backbone area is special, because it is responsible for the other area can be connected each other. And what about stub area? Stub types of areas help us to reduce the LSDB as