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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 ?

    Davis

  2. Hi Davis,

    I’m afraid not. The AutoRP addresses 224.0.1.39 and 224.0.1.40 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:

    https://networklessons.com/cisco/ccie-routing-switching/dmvpn-phase-3-ospf-routing/

    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 1.1.1.1
    

    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
    Hub(config
    ... 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:

    //cdn-forum.networklessons.com/uploads/default/original/1X/45c5f4cfbaf80921dc7da699241007f586549885.jpg

    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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