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Forum Replies

  1. hi thank you for your article

    as i see this post, i have a one question

    in this situation, if host 2 was silently shut off, how does the switch delete igmp snooping table?

    if host1 was silently shut off, host2 don’t receive igmp membership report because of longer mrt, host2 send igmp memgership report message to router…

    in the situation that hosts with longer mrt was silently shut off, how do the switches delete igmp snooping table???

    thanks

  2. Hi Rene,
    Have Question about report suppression.
    If both hosts within same multicast group (239.1.1.1) 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.

    thanks.
    Amit

  3. Hi Hussein,

    Membership reports are sent to the specific multicast group address:

    https://www.cloudshark.org/captures/909766aa3ea6

    Membership leave group messages are sent to the 224.0.0.2 (all routers) address:

    https://www.cloudshark.org/captures/7d789d000734

    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.

  4. Hello Saif

    In IGMPv1, there is no election process for the active querier. However, if there are two IGMPv1 routers on the same subnet, then it is the Designated Router (DR) that will also perform the role of the querier. The designated router is elected exactly for the purpose of avoiding the duplication of multicast traffic for connected hosts.

    More information about this can be found here:

    https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/15-2_2_e/multicast/configuration_guide/b_mc_1522e_3750x_3560x_cg/b_ipmc_3750x_356

    ... Continue reading in our forum

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