3. Definition of Current Assignment Practice
Unlike IPv4 unicast address assignment, where blocks of addresses are delegated to Regional Internet Registries (RIRs), IPv4 multicast addresses are assigned directly by the IANA. Current registration groups appear as follows [IANA]:
| Address Range | Size | Designation |
|---|---|---|
| 224.0.0.0 - 224.0.0.255 | (/24) | Local Network Control Block |
| 224.0.1.0 - 224.0.1.255 | (/24) | Internetwork Control Block |
| 224.0.2.0 - 224.0.255.255 | (65024) | AD-HOC Block I |
| 224.1.0.0 - 224.1.255.255 | (/16) | RESERVED |
| 224.2.0.0 - 224.2.255.255 | (/16) | SDP/SAP Block |
| 224.3.0.0 - 224.4.255.255 | (2 /16s) | AD-HOC Block II |
| 224.5.0.0 - 224.255.255.255 | (251 /16s) | RESERVED |
| 225.0.0.0 - 231.255.255.255 | (7 /8s) | RESERVED |
| 232.0.0.0 - 232.255.255.255 | (/8) | Source-Specific Multicast Block |
| 233.0.0.0 - 233.251.255.255 | (16515072) | GLOP Block |
| 233.252.0.0 - 233.255.255.255 | (/14) | AD-HOC Block III |
| 234.0.0.0 - 238.255.255.255 | (5 /8s) | RESERVED |
| 239.0.0.0 - 239.255.255.255 | (/8) | Administratively Scoped Block |
The IANA generally assigns addresses from the Local Network Control, Internetwork Control and AD-HOC blocks. Assignment guidelines for each of these blocks, as well as for the Source-Specific Multicast, GLOP, and Administratively Scoped blocks, are described below.