Multicast Tunnel Creation

I have noticed that a tunnels gets auto created both in Static RP and Auto RP, both on the Hub router and on the leaf router.

However there are two tunnel interfaces on the Hub and only single on the leaf router.

Please correct if I am wrong.

My Query:

If there are three or more leaf PIM routers, will we have more tunnel interfaces on the hub router ?



  • Guys, any comments ???

  • I dont think so.

    If I remember well one tunnel is always present on all PIM enabled routers (though only with recent IOS version). It is used as a standard interface to encapsulate Register message that are being sent to the RP.

    A second tunnel is also present on every router that act has an RP. I cant remember the details of why this is so, maybe to receive those Register Message ? I dont think you would get more tunnels if you add more leaf routers, but you could test it easily I guess ;-)

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