Open Issues
Security:
- receivers are unknown, so watch out for eaves-dropping
- do you really want to access and policy control the multicast sources? See the I-D draft-ietf-mboned-mcast-firewall-02.txt
Scalability
- keeping group state can be expensive, with 10,000s of multicast groups around
- the 3rd party RP problem (a.k.a., where do you put the root of the shared tree?) -- connecting multiple PIM-SM domains
- multi-level RPs, anycast clusters, Multicast Source Discovery Protocol (MSDP), directory services (e.g., DNS)
- Multicast address allocation and construction of inter-domain multicast distribution trees - Border Gateway Multicast Protocol (BGMP)