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  • 1.  How can I quickly identify which prefixes are originated from an OSPF areas on an ABR ?

    Posted 03-13-2021 19:06

    How can I quickly identify the all the prefixes originated from Area 1? so I can configure an aggregate route.
    The following (from my lab topology that is too big to post here ) seems telling me the numbers of routes, how can I know the prefixes ?
    root@SRX-3# run show ospf database summary area 2    
    Area 0.0.0.2:
       3 Router LSAs
       2 Network LSAs
       2 Summary LSAs
       6 NSSA LSAs
    Externals:
       10 Extern LSAs
    Interface ge-0/0/0.37:
    Area 0.0.0.2:
    ​

    thanks a lot in advance !!



  • 2.  RE: How can I quickly identify which prefixes are originated from an OSPF areas on an ABR ?

    Posted 03-20-2021 19:42
    The `show ospf database summary [area]` command tells you the summary of the link-state database (LSDB), you would need to infer from it which LSAs represent prefixes.

    1. For example, you have Router LSAs, these LSAs will not only contain the topology information (nodes), but also the network-layer reach-ability information (NLRI), by looking at this command you won't be able to infer which routes are being advertised.
    2. Summary LSAs will contain info for the inter-area prefixes, in this case you have 2 Summary LSAs, which means you have two inter-area advertisements.
    3. NSSA LSAs means this area is holding type-7 LSA information, and these 6 NSSA LSAs were generated locally by redistribution of external prefix information (export policies somewhere in the NSSA), this means you have six prefixes that area NSSA.
    4. External belong to the OSPF domain, and you have a total count of 10 External LSAs, which means 10 External prefixes.

    If you want to know the details, you would need to expand it directly by the LSA type as in `show ospf database <LSA TYPE>` command.

    Elvin


  • 3.  RE: How can I quickly identify which prefixes are originated from an OSPF areas on an ABR ?

    Posted 03-20-2021 20:40
    thanks a lot !!


  • 4.  RE: How can I quickly identify which prefixes are originated from an OSPF areas on an ABR ?

    Posted 03-21-2021 04:51
    Welcome!

    Elvin