#1 Restrict igmp reports for downstream interfaces


atm all igmp membership reports are forwarded to the upstream interface. Unfortunately some ISP Providers restrict some multicast groups (esp. those that are defined as local link groups and that are not supposed to be forwarded to the wan, i.e Therefore there should be some kind of black oder whitelisting.
As whitelisting can be accomplished quite easy I wrote a litte patch, which is attached to this request.


  • Constantin Baranov

    I think this patch would go into 0.2 release.
    But could you please clarify why should we restrict multicast groups by igmpproxy itself? What a bad happens if downstream joins restricted group (and igmpproxy forwards request therefore)?

  • Grinch

    Grinch - 2009-08-15

    >What a bad happens if downstream joins restricted group (and igmpproxy forwards request therefore)?

    Speaking for my ISP (T-Home - Germany - new network architecture): a membership report containing one or more local link groups is illegal and being ignored completely. As IGMP v3 is used all groups are requested with one report. If a local device joined a local network group, all multicast groups are dropped after 30 seconds (membership query every 10sec, robustness 2) which leads to an outage of iptv streams that use multicast. After some time the devices request their groups again, one after another which leads to single reports, so the groups are coming up again, but replies to the general membership queries are still ignored by the querier, so after 30 seconds the procedure starts all over.

    so black- or whitelisting is a convenient way to still use local multicast without interfering wan multicast.

  • Constantin Baranov

    • status: open --> closed-fixed

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