I am considering implementing a large scale private MPLS network. The application to be used over it will need to support multicasting of at least voice traffic. Because I will have total control over the router/switching infrastructure is the configuration a standard multicast config or are there MPLS specific isuues I'll need to deal with. All the docs I can find talk about running multicast ove a provider based network. I'm concerned with how this will work over MPLS. ie: if multiple joins to a common stream are issued from disaprate areas/routers in the network, will a stream be unicast to each RP (PIM sparse) that is upstream from the join request source? Or can I multicast across MPLS to the RP's?
MPLS doesn't support multicast natively yet. You need to wait for mLDP (http://www.ietf.org/internet-drafts/draft-wijnands-mpls-mldp-in-band-signaling-00.txt)
So MPLS will be used to forward unicast traffic and in // you will have PIM deployed as usual for multicast traffic.
SP deployed mVPN to support multicast into a L3VPN. But even mVPN is not based on MPLS in the SP core.