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  1. Rene,

    Based on the below entry:
    "Above you can see that R2 is receiving the RP announcement traffic from R1. Let’s check R3:

    R3#show ip mroute | begin 224
    (*, 224.0.1.39), 00:05:28/00:01:57, RP 0.0.0.0, flags: DC
      Incoming interface: Null, RPF nbr 0.0.0.0
      Outgoing interface list:
        GigabitEthernet0/2, Forward/Sparse, 00:05:28/00:01:57
    
    (*, 224.0.1.40), 00:27:34/stopped, RP 0.0.0.0, flags: DPL
      Incoming interface: Null, RPF nbr 0.0.0.0
      Outgoing interface list: Null
    
    (2.2.2.2, 224.0.1.40), 00:04:29/00:02:29, flags: PLT
      <strong>Incoming interface: GigabitEthernet0/2</strong>, RPF nbr 192.168.23.2
      Outgoing interface list: Null
    "
    

    If I am not wrong, the incoming interface should be Gi0/1, which is the interface connected towards the RP mapping agent (2.2.2.2). Gi0/2 is the interface connected to GI0/4.

    Let me know if I am missing something.

    Thanks,

    Jose

  2. @Hans redundancy is no problem but you should configure multiple RPs AND multiple mapping agents. Otherwise a single mapping agent is your single point of failure.

    @Abhishek CGMP is pretty old so it’s possible that this command is not even needed in your network. It’s used for within your L2 domain:

    The ip pim passive command means that the switch/router won’t send any PIM messages on its interface, it will also not accept any PIM messages from other devices. It forces your switch/router to become the DR. If you need PIM and you are the only PIM-enabled device, you can use this. Otherwise you should disable it.

    Adding ip pim autorp listener only makes sense if you use sparse mode, not dense or sparse-dense mode.

  3. Hello Parajuli

    Although Rene doesn’t go into details in the lesson, a router is configured as a mapping agent using the following command:

    ip pim send-rp-discovery

    You can find out more about this command at this Cisco Command Reference Documentation (search for ip pim send-rp-discovery.

    It is possible to configure two or more mapping agents within a network. Each will function independently. Engineers often misunderstand how multiple mapping agents interact and often believe that there is more complexity to such a configuration than there really is. Receiving mapping data from two or more mapping agents is not a problem because both transmit identical mapping information, so there are never any conflicts.

    Conversely, the command ip pim send-rp-announce configures a router as an RP.

    I hope this has been helpful!

    Laz

  4. Hello Deep

    Routers will only play the role of a RP or an MA if they are statically configured as such. Specifically, to configure a router as a candidate RP and thus to have it announce itself as such, the following command must be present:

    ip pim send-rp-announce

    To configure a router as an MA the following command must be present:

    ip pim send-rp-discovery

    The above are configured on R1 and R2 respectively. R4 is not configured to announce itself as an RP so it will not do so. R4 does however recieve the information from the mapping agent because of the following command that is found on R3

    ip pim autorp listener

    This command allows the multicast traffic that reaches R3 to be flooded with dense mode, thus it will flood those packets to R4.

    I hope this has been helpful!

    Laz

  5. It seems Cisco officially recommend to use sparse-dense mode rather than auto-rp listener, and dummy rp’s for the groups which don’t exist.

    Which frankly makes little sense to me, as listener requires way less config!

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