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Forum Replies

  1. Thanks! I do have some plans for next year…so I’m afraid you’ll have to find another study book for the moment :slight_smile:

  2. Rajendra,
    This has to do with how link state protocols work. In order for a link protocol to be able to run the Dijkstra algorithm, they must all have identical databases to run the algorithm against. If filtering were allowed within an area, then by definition, some routers would have a different database than others, and when those routers ran the shortest path tree calculations, they would arrive at different results.

    Notice that both the ASBR and ABR, by definition, are at the area boundary. They are allowed to do filtering or summarization only on route

    ... Continue reading in our forum

  3. Never mind I figured this out. Basically to block the route for 4.4.4.1, I should make an exact match in my prefix-list.

    So basically I changed

    ip prefix-list into_area3 seq 7 deny 4.4.4.1/24

    TO

    ip prefix-list into_area3 seq 7 deny 4.4.4.1/32

    And it works.

  4. Hello Helen.

    I am assuming that you and the ISP are operating completely separate OSPF domains. That is, their OSPF routing is completely autonomous from yours. This means that your area 0 has nothing to do with their area 0. They are two completely separate systems.

    If this is the case, then the way one OSPF domain communicates with another OSPF domain is via a router that has two separate OSPF processes running. One interface is using process number 1 for example, this may be your internal OSPF domain, and the outside interface is using process 2, which i

    ... Continue reading in our forum

  5. Hello
    By using filtering on ABR, does this method tell the ABR not to advertise this prefix list or it tell the router in the area not to install this prefix in their routing table ?
    Thank
    Sovandara

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