UDP Peer Discovery

224.0.0.0 - 239.255.255.255 are the reserved multicast IP addresses, these are class D addresses.

IP Address Usage
224.0.0.1 All systems on this subnet
224.0.0.2 All routers on this subnet
224.0.0.5 OSPF routers
224.0.0.6 OSPF designated routers
224.0.0.12 Dynamic Host Configuration Protocol (DHCP) server/relay agent

Globally Scoped Addresses

Addresses in the range from 224.0.1.0 through 238.255.255.255 are called globally scoped addresses. These addresses are used to multicast data between organizations and across the Internet.

IP Multicasting Components

Component Description
Host (source or receiver) A host is any client or server on the network. A multicast-enabled host is configured to send and receive (or only send) multicast data.
Router A multicast router is capable of handling host requests to join or leave a group and of forwarding multicast data to subnets that contain group members.
Multicast address A Class D IP address used for sending IP multicast data. An IP multicast source sends the data to a single multicast address. A specific IP multicast address is also known as a group address.
Multicast group A multicast group is the set of hosts that listen for a specific IP multicast address. A multicast group is also known as a host group.
MBone The Internet multicast backbone, or the portion of the Internet that supports multicast routing.

Unicast Routing Characteristics

Multicast Routing Characteristics

Multicast Groups

The set of hosts listening for a specific IP multicast address is called a multicast group or a host group. Multicast groups have the following attributes: