IGMP helper address

Hello!

I have multicast tunnel betwen two routers. I would like to pass igmp join/leave etc messages from one to another. At client site i use ip igmp helper-address to first router where i can get multicast streams. igmp packets gets to first router but are not send out. I use pim dense-mode. I would like to specify interface name in ip igmp help-address commad but command only accept IP address. Should i use some other command (ip igmp proxy or something else) to send out igmp packets on proper interface.

Thanks, best regards

Peter

Comments

  • is this related to vol1 "8.21 Stub Multicast Routing & IGMP Helper" ?

  • Dear Peter,

    Please Post a Topology and clarify your need.

  • Hello!

    Topology is like on this link http://gns3vault.com/Multicast/multicast-stub-a-igmp-helper.html

    I use ip igmp helper-address on both routers hop by hop ... I also use pim between both routers without neighbour-filter.

    Murdock:

    ip multicast-routing

    ip pim bidir-enable

    ip mroute VideoStation -> BA (for rpf check since router has default route and so on ...)

    lan interface

     ip igmp helper-address BA

     ip pim dense-mode

     

    BA:

    ip multicast-routing

    ip pim bidir-enable

    interface to murdock

     ip pim dense-mode

     ip igmp helper-address "broadcast address of interface to VideoStation"

    ip route "broadcast address of interface to VideoStation" -> interface to VideoStation

     

    This configuration works, but I would say that there is a better way ,...

     

     

  • Dear Peter,

    The whole purpose of IGMP helper address is not to use PIM join/prune messages, thus creating "PIM stub domain". Currently the topology works for you because of PIM dense-mode not igmp helper-address feature

     

    Non-standard multicast traffic recieved on non-pim enabled interface will be dropped. Igmp message re-routing works only through pim enabled interfaces with no pim neighbour. B/c of these combination efects, you must enable pim neighbour-filter on murdock's link to BA.

     

    Also it is useless to use igmp helper address on BA b/c :

    1. BA is the DR next to the multicast source VideoStation.
    2. It works only if the upstream device is a PIM aware device and not the multicast source.

     

    I recommend you configure like this:

     


    Murdock:

    ip multicast-routing

    ip pim bidir-enable           // no need, since you are testing only one-direction traffic

    ip mroute VideoStation     // no need, since there is only one possible path and default route will do just fine.

    !


    Lan interface to client

     ip igmp helper-address BA

     ip pim dense-mode

    !

    interface to BA

      ip pim dense-mode


    !

     

    BA:

    ip multicast-routing

    ip pim bidir-enable           // no need, since you are testing only one-direction traffic

    !

    interface to murdock

     ip pim dense-mode

     ip pim neighbour-filter 99

     ip igmp helper-address "broadcast address of interface to VideoStation"     // totally no use 

    !

    interface to videostation

     ip pim dense-mode

    !

    access-list 99 deny  BA's address

    access-list 99 permit any

    !

    ip route "broadcast address of interface to VideoStation" -> interface to VideoStation  // no use



     

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