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Forum Replies

  1. Hi Rene,

    Is the mapping agent behind spoke issue also can be solve by this command ip pim NBMA-mode ?


  2. Hi Davis,

    I’m afraid not. The AutoRP addresses and are using dense mode flooding and this is not supported by NBMA mode. If your mapping agent is behind a spoke router then you’ll have to pick one of the three options to fix this:

    • Get rid of the point-to-multipoint interfaces and use sub-interfaces. This will allow the hub router to forward multicast to all spoke routers since we are using different interfaces to send and receive traffic.
    • Move the mapping agent to a router above the hub router, make sure it's not behind a spoke router.
    ... Continue reading in our forum

  3. Hi Hussein,

    I first thought you would need ip pim nbma-mode on the hub tunnel interface but in reality, we don’t. For example, take this topology:


    Then add these additional commands:

    Hub, Spoke1 & Spoke2
    (config)#ip multicast-routing
    (config)#interface Tunnel 0
    (config-if)#ip pim sparse-mode
    (config)#ip pim rp-address

    The loopback of the hub is the RP so I need PIM sparse mode there too, and we need NBMA mode on the tunnel:

    Hub(config)#interface Loopback 0
    ... Continue reading in our forum

  4. Hi Hussein,

    I had to think about this for awhile and do another lab…something interesting happened :smile: With the DMVPN topology that I usually use (switch in the middle), multicast traffic went directly from spoke1 to spoke2. Take a look at this Wireshark capture:


    The ICMP request from spoke1 isn’t encapsulated. The reply from spoke2 is.

    So I labbed this up again, replaced the switch in the middle with a router. When you do this, all multicast traffic from spoke1

    ... Continue reading in our forum

  5. Hi Hussein,

    I just redid this lab on some real hardware and I think this is some Cisco VIRL quirk. When I run it on VIRL, I don’t need to use PIM nbma mode. On real hardware, I do need it.

    Spoke1-VIRL#show version | include 15
    Cisco IOS Software, IOSv Software (VIOS-ADVENTERPRISEK9-M), Version 15.6(3)M2, RELEASE SOFTWARE (fc2)
    Spoke1-REAL#show version | include 15
    Cisco IOS Software, 2800 Software (C2800NM-ADVENTERPRISEK9-M), Version 15.1(4)M7, RELEASE SOFTWARE (fc2)

    Let’s join a group:

    Spoke2(config)#interface gi0/0
    Spoke2(config-if)#ip igmp join-group 239.3.3
    ... Continue reading in our forum

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