Configuring IP Multicast
IP multicast address ranges

The IANA controls the assignment of IP multicast addresses. IANA has assigned the IPv4 Class D address space to be used for IP multicast. Therefore, all IP multicast group addresses fall in the range from 224.0.0.0 through 239.255.255.255. The Class D address is used for the destination IP address of multicast traffic for a specific group. The source address of a multicast datagram is the unicast address of the device sourcing the multicast flow to the destination multicast address.

Reserved Link-Local Addresses
The IANA has reserved addresses in the range 224.0.0.0 to 224.0.0.255 to be used by network protocols on a local network segment. A router should never forward packets with these addresses. Packets with link-local destination addresses are typically sent with a Time to Live (TTL) value of 1 and are not forwarded by a router. Network protocols use these addresses for automatic router discovery and to communicate important routing information. For example, Open Shortest Path First (OSPF) Protocol uses the IP addresses 224.0.0.5 and 224.0.0.6 to exchange link-state information.

Address 224.0.0.1 identifies the all-hosts group. Every multicast-capable host must join this group. If a ping command is issued using this address, all multicast-capable hosts on the network must answer the ping request.

Address 224.0.0.2 identifies the all-routers group. Multicast routers must join that group on all multicast-capable interfaces.

Globally Scoped Addresses
Multicast addresses in the range from 224.0.1.0 through 238.255.255.255 are called "globally scoped addresses." They can be used to multicast data between organizations and across the Internet. Some of these addresses have been registered with IANA, for example IP address 224.0.1.1 has been reserved for Network Time Protocol (NTP).

Source Specific Multicast Addresses
Addresses in the 232.0.0.0 to 232.255.255.255 range are reserved for Source Specific Multicast (SSM). SSM is an extension of Protocol Independent Multicast (PIM), which allows for an efficient data delivery mechanism in one-to-many communications.

GLOP Addresses
Multicast GLOP (a word, not an acronym) addresses in the range 233.0.0.0 to 233.255.255.255 can be used statically by organizations that have an Autonomous System (AS) number registered by a network registry and listed in the RWhois database. The second and third octets of the domain multicast address are represented by the AS number. For example, AS 62010 is written in hexadecimal format as "F23A." This value is separated into two parts, F2 and 3A and those numbers, converted to decimal would be 242 and 58. This would yield a multicast GLOP address of 233.242.58.0/24. Multicast group addresses in that address space can be used by the organization with AS 62010 and routed throughout the Internet Multicast Backbone.

Limited Scope Addresses
Like private IP address space that is used within the boundaries of a single organization, "limited" or "administratively scoped" addresses in the range 239.0.0.0 to 239.255.255.255 are constrained to a local group or organization. Companies, universities, or other organizations can use limited scope addresses to have local multicast applications that will not be forwarded over the Internet. Typically, routers are configured with filters to prevent multicast traffic in this address range from flowing outside of an AS. Within an autonomous system or domain, the limited scope address range can be further subdivided so that local multicast boundaries can be defined. This subdivision is called "address scoping" and allows for address reuse between smaller domains. These addresses are described in RFC 2365, Administratively Scoped IP Multicast.