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Forum Replies

  1. Hi Rene,

    I have several questions :-

    1 - Can we have ABR between sub areas or the ABR must be only between backbone area and sub areas ?
    2 - Can we have the ASBR in sub areas or the ASBR must be only in the backbone area ?
    3 - What is the different between saves address space and used address space that you mentioned in the advertisement of loopback interface addresses ? I did not understand that and I have some ambiguity at this point ? can you explain it to me in detail please ?
    4 - what is the benefit of sharing information with OSPF hello packets like Rout

    ... Continue reading in our forum

  2. Thank you so much for your answer and patience.

    I already did what you told me for static routes and I will do the same to redistribute BGP prefix list to OSPF.

    If I already have BGP filters (prefix-list) can I use the same prefix-lilst to create a route-map to filter the networks announce by BGP to OSPF?

    example

    router bgp 65533
     neighbor 6.6.6.6  remote-as 65533
     neighbor 6.6.6.6 update-source Loopback0
     neighbor 6.6.6.6 prefix-list PRUEBA in
    
    ip prefix-list PRUEBA permit ip 10.250.20.0/24   --> ( I have a lot of prefix list for filtering but that is for tha
    ... Continue reading in our forum

  3. Great Web Lesson Rene!

    Word of advice buy Rene book on CCNP Route. Study the chapters such as I read all of the OSPF chapters through twice. Then I come to the web pages which I buy a year subscription to at a time as its a little cost savings.

    On the web pages especially one like this where Rene has video its great to watch those as added reinforcement.

    For example, First video Rene is talking about all the areas and how OSPF works. he shows you a ABR and ASBR. When he is doing this if you have studied the book first you are seeing LSA type 3 summary ne

    ... Continue reading in our forum

  4. Hello Rene,
    I did a packet capture and was studying Hello packet in ospf.
    My setup here is like this R1------------------------------R2
    192.1681.1.1 192.168.1.2
    I enabled OSPF on R2 first so it started sending Hello packet, then next I configured OSPF on R1 so now R1 also started sending hello packet. Now as soon as R2 got the hello from R1 then it did an ARP saying who is 192.168.1.1 tell 192.168.1.2. So why this ARP happens at first place and I see this ARP happening on R2 only not on R1, my second question.
    I am also attaching the packet capture.hello.pcapng (13.0 KB)

  5. Hello Ravi

    This is an excellent question, it shows that you are thinking analytically and very deeply about these issues.

    When a router sends an OSPF hello packet, it sends it to the 224.0.0.5 multicast address. When R2 receives this packet, one of the pieces of information it receives in the OSPF header is the IP address of the router that sent it.

    Now the next step to establishing a neighbour adjacency is for R2 to respond with a unicast packet sending its router ID and its neighbour list. However, in order to do this, it must encapsulate the response, whic

    ... Continue reading in our forum

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