5.2 Multicast - why tunnel ?

Hi all,

Does anyone know why in this task we have a tunnel in the SG as opposed to "ip pim nbma-mode" ?

 

Cheers,

K.

Comments

  • PIM-DM does not work over traditional NBMA networks unless a full mesh topology is used. Even if one does use a full mesh topology of virtual circuits to build the NBMA cloud, the performance impact of pseudobroadcast remains, making PIM-DM a poor choice for NBMA networks.

     

     Beau Williamson, Cisco Press CCIE Developing Ip Multicast Networks.

  • Got it.

    Cheers mate, but where this .13. comes from ?

     

    Thanks

  • it is an arbitrary chosen number, easy to guess what devices participate in tunneling(in this case R1 and R3). You should already know that scheme since this is lab #9

  • Yep I guess I do...but used another arbitrary subnet in a mock and got a zero; he says you're only allowed to use unnumberred ifs in cases like this...arrrrggggh

     

  • I thought you are asking about tunnel number, not tunnel subnet id, sorry. For this particular task we are indeed allowed to use any arbitrary numbering for tunnel's subnet, just reread lab do's and dont's section. When we aren't allowed - there is no choice of using unnumbered feature.

  • Yep mate. that's cool. thanks for suggesting this.

    Just went through the unnumberred stuff and it's up and running now : For instance :

    Rack1R3(config-if)#do sh run int tun0
    Building configuration...

    Current configuration : 131 bytes
    !
    interface Tunnel0
     ip unnumbered FastEthernet0/0
     ip pim dense-mode
     tunnel source Loopback0
     tunnel destination 150.1.1.1
    end

     

    Cheers,

     

  • I'm unable to make this work, unless I enable ip pim dense-mode on Loopback0. I don't see anywhere in the documentation that this is a requirement, meaning enabling pim on the source interface of the tunnel, but it is the only way I can get it to work.

    Any thoughts?

     

  • Hi,

     

    I had to put tunnel interfaces in RIP passive mode, due to recursive routing

     

    jofo

  • The answer also calls for an ip mroute 0.0.0.0 0.0.0.0 to the tunnel. Isn't this considered a static route? The Lab rules say you cannot use a static route. Task 5.2 does not state that you can use a static route.

  • <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">





    I would not consider an mroute a "static route".  If you're not sure
    what is or is not permitted in the lab I would recommend to ask the
    proctor.



    Brian McGahan, CCIE #8593 (R&S/SP/Security)

    [email protected]

     

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    dloughlin wrote:

    The answer also calls for an ip mroute 0.0.0.0 0.0.0.0 to the
    tunnel. Isn't this considered a static route? The Lab rules say you
    cannot use a static route. Task 5.2 does not state that you can use a
    static route.







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  • I would not consider an mroute a "static route".  If you're not sure
    what is or is not permitted in the lab I would recommend to ask the
    proctor.


    Brian McGahan

     

    Really? Better ask!

    R1#sh ip rpf 148.1.3.3
    RPF information for ? (148.1.3.3)
      RPF interface: Tunnel13
      RPF neighbor: ? (148.1.3.3)
      RPF route/mask: 0.0.0.0/0
      RPF type: static
      RPF recursion count: 0
      Doing distance-preferred lookups across tables

  • hi all,

    i have some questions on this weird taks,

    i did not considered a tunnel before going here and looking at post's subjects, [:^)] , i said ok, let's go with tunneling. i created a tunnel but

    from R3 to R6 ! it works fine with no ip mroute command. should this be considered good or bad?

    thanks in advance

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