RP Mappings

Hello Experts,

the task states that SW2 should be responsible for the group tp RP mapping; the network is running in sparse mode. The SG configured SW2 to use loopback 0 as the interface with the following command:

ip pim send-rp-discovery lo0 scope 16

I use the following command without specifying any interface and it worked out fine:

ip pim send-rp-discovery scope 16

My thought is since the task did not specify anything in the line of "use SW2's most reliable interface for RP mappings" I did not specify it.

 

Can someone please explain the difference between the two commands and what's best to use as far as the CCIE lab goes.

 

Best regards

Comments

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    If you do not specify the interface, it will source
    separately out of each PIM-enabled interface on the device.

     

    This may or may not cause a problem for you, depending on
    reachability you have in your lab and any RPF issues along the way instead of a
    single-sourced address.

     

    But both will work perfectly fine (you did verify function,
    right?), and if the lab doesn't say anything about reliable interface, then it
    doesn't matter whether you do or do not.

     

    From a design standpoint, it's best to use loopbacks for
    things that should always be working.  But beyond that, no matter as long
    as you aren't violating any other rule.

     

    HTH,

     




    Scott Morris, CCIE4 #4713, JNCIE-M #153, JNCIS-ER, CISSP, et al.
    CCSI/JNCI-M/JNCI-ER
    Senior CCIE Instructor

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    From: [email protected] [mailto:[email protected]]
    On Behalf Of ndiayemalick
    Sent: Wednesday, September 17, 2008
    12:26 AM
    To: [email protected]
    Subject: [CCIE
    R&S] RP Mappings


    Hello Experts,

    the task states that SW2 should be responsible for the group tp RP mapping;
    the network is running in sparse mode. The SG configured SW2 to use loopback 0
    as the interface with the following command:

    ip pim send-rp-discovery lo0 scope 16

    I use the following command without specifying any interface and it worked
    out fine:

    ip pim send-rp-discovery scope 16

    My thought is since the task did not specify anything in the line of "use
    SW2's most reliable interface for RP mappings" I did not specify it.

     

    Can someone please explain the difference between the two commands and what's
    best to use as far as the CCIE lab goes.

     

    Best regards




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    Preparation
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  • Thanks Scott for the explaination.

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