From: Adam Crisp (adam.crisp@totalise.co.uk)
Date: Tue Oct 29 2002 - 04:43:51 GMT-3
Hi Group.
I am confused about how the Intnet filters multicast sources.
A question about Multicast and Sparse mode - and then MSDP and MBGP.
I am correct in saying that a group source, and a group receiver registers
itself with the RP using the same method?
ie.
1. A receiver joins a group, through IGMP, and then starts listening to
packets received.
2. A souces joins a group, through IGMP, and then starts tranmitting packets
to the group.
If so, then how does the Internet distingush between receives and senders?
I have done the following.
I have two AS's and the RP's run MSDP between them. I also run MBGP.
There is a PIM boundary between the two AS's.
MSDP exchanges "source" information, and MBGP is used for RPF.
I have made a router in each PIM domain a member of a group using the ip
igmp join 234.0.0.1
This set up works.
How then, does the Internet distinguish between Sources and Receivers.
ie. Only certain customers are allowed to source.
Anybody is allowed to receive.
If Supplier A at ISP A has a source 234.0.0.1 - then anybody on the interet
has to be able to join this group
eg Customer A at ISP B joins the 234.0.0.1 and receives the traffic.
What is there to stop Supplier C at ISP B to start transmitting on
234.0.0.1 - using IGMP and break the "real" source.
thanks
Adam
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