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Forum Replies

  1. Hi Rene,

    In regards to:
    <h3>OSPF NSSA ASBR and ABR</h3>
    You say: “When an OSPF NSSA router is both ASBR and ABR then it can flood LSA type 7 or LSA type 5 directly in another area. For this reason, the P-bit will be disabled on type 7 LSAs.”

    I feel i am missing something here.

    When you make R2 both ABR and ASBR by redistributing R2’s loopback , you say the conversion from 7 to 5 does not happen.

    But Still R1 gets the type 5 for the loopback from R2?

    I mean, if the P bit is not set, then how can this redistributed loopback on R2 make it to R1 as a type5?

    What i

    ... Continue reading in our forum

  2. Hi Edwin,

    In case anyone else reads this, we are talking about this post right:

    https://networklessons.com/ospf/ospf-nssa-p-bit-explained/

    You are correct. In this example, R2 will create a LSA type 5 directly which R1 can learn and a LSA type 7 that R4 will learn. There’s no need to create a LSA type 7 and then translate it into a type 5, that’s why the P-bit is disabled.

    Rene

  3. Pradeep,
    I assume you mean the following command
    translate type7 suppress-fa

    To answer this question, you first need to understand how a Type-5 External advertisement changes when it is translated by an NSSA ABR. When an LSA Type-7 to Type-5 translation occurs (only an NSSA ABR can do this), two properties change: 1) The advertising router and 2) The Forwarding Address.

    Regular Type 5 LSA
    In a regular (not translated) Type-5 LSA, the Advertising router is the ASBR itself, and the Forwarding Address is 0.0.0.0

    Regular Type 5 LSA

    LS Type: AS External Link
      Lin
    ... Continue reading in our forum

  4. Hi Rene, The “P” bit now has a spot where the “NP” was in Wireshark, on the top of the section it’s actually called Propagate. Just an FYI

    Great Practice Site, I passed my CCIE Route Switch two months ago…

    Mike

  5. Hi Rene,

    Will the forwarding address be changed when ABR summarize the external route to other areas?

    I thought Forwarding Address will be always ASBR address and Advertising router field will be changed.

    But below point confused me.

    To reach 5.5.5.5/32 we have to use forward address 192.168.45.5. R1 will use both R2 and R3 to reach this network:

    R1#show ip route 5.5.5.5
    Routing entry for 5.5.5.5/32
      Known via "ospf 1", distance 110, metric 20, type extern 2, forward metric 3
      Last update from 192.168.13.3 on FastEthernet0/1, 00:00:22 ago
      Routing Descriptor
    ... Continue reading in our forum

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