Hi,
I would like to know why MBGP is used for multicast ? I came across some document which says that it is used for RPF checks and MP_REACH_NLRI is being used to carry that info, but I would like to know why the regular BGP cannot be used for this purpose. I know that MBGP is not a multicast routing protocol, but would like to clarify its role in multicasting.
Is it used in conjunction with BGMP ? If yes, please clarify.
Thanks, asm
BGP carries unicast routing information only.
Multicast routing within a network (AS) is typically done with PIM-SM
So the question becomes one of how exchange the multicast routing(PIM-SM) information between different Internet Service providers.
Since ISP's all use BGP to exchnage routing informatio, it was logical to look for a way to enhance BGP to also carry multicast routing information - voila MBGP
So MBGP(exterior to AS) is to PIM-SM (Interior to AS) for multicast routing, what BGP (exterior to AS) is to OSPF/ISIS (interior to AS) for unicast routing.
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