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Forum Replies

  1. Hi Hamood,

    PIM is the protocol we use between multicast-enabled routers to forward multicast traffic, it has three modes:

    - sparse
    - dense
    - sparse-dense

    When we use any of the two sparse modes, we use a central point in our traffic where we forward multicast traffic to. This is called the RP (Rendezvous Point).

    This RP can be statically configured or it can be learned through auto RP.

    Auto RP uses the multicast address.

    Once I write about the PIM modes, I’ll cover this in detail.


  2. Hi Rene,
    Have Question about report suppression.
    If both hosts within same multicast group ( wants to receive the multicast traffic then both will send membership report, but why only HOST1 with lower MRT is able to send membership report and other host2 can not (as it receives membership report from other host1)
    I think it is required for each host to send membership report to receive multicast traffic.
    In above case if HOST 2 won’t send report (as it receive report from HOST1) to router then how it will receive the traffic.

    Please advise.


  3. Hi Rene,

    Why the membership report sends to - multicast addresses and the leave membership sends to (all routers) ?? I need to know when the IGMP use group specific address and when use all router multicast address and why ??

  4. Hi Hussein,

    Membership reports are sent to the specific multicast group address:


    Membership leave group messages are sent to the (all routers) address:


    RFC 2236 explains why:

    Leave Group messages are addressed to the all-routers group because other group members have no need to know that a host has left the group, but it does no harm to address the message to the group.

  5. Hi Rene,

    Can you give a tutorial on IGMP Fast-Leave and IPTV?


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