The IPv4 multicast address space (224.0.0.0-239.255.255.255) has been divided to multiple diffent parts with different allocation and routing policies that may depend on where you are located. The best source for current information is your network service provider's multicast routing expert who should coordinate routing with TERENA and RIPE.

Here's a quick overview of various address ranges as seen from the Funet network which has multicast connectivity via NORDUnet to at least GEANT and Internet 2 networks. This page is by no means complete. New allocation methods and address ranges are being agreed in various forums. For GEANT backbone users the Dante MBONE-pages should provide more information.

The SSM and GLOP ranges might suit applications needing a semi-permanent address or other special needs as detailed in the relevant RFCs. As always, please check your local routing and filtering setups as well as the relevant allocation authorities before using of most other addresses than the traditional SAP dynamic assingments.

Scoped addresses are a very efficient way to limit the reach of a multicast group but not implemented everywhere yet. No information about the group should flow beoynd the scope boundary so it should lessen the load on routers, allow address space reuse and improve security and stability provided the scoping is well implemented in all border routers.