Multicast IP addresses

Multicast uses the Class D address space. The 224.0.0.0 to 239.255.255.255 IP address range is reserved for multicast groups. The multicast address range applies to multicast groups, not to the originators of multicast packets. Table 53 lists reserved multicast address ranges and describes what they are reserved for:

Table 53: Reserved Multicast address ranges
Reserved Address Range	Use	Notes
224.0.0.0 to 224.0.0.255	Used for network protocols on local networks. For more information, see RFC 1700.	In this range, packets are not forwarded by the router but remain on the local network. They have a Time to Live (TTL) of 1. These addresses are used for communicating routing information.
224.0.1.0 to 238.255.255.255	Global addresses used for multicasting data between organizations and across the Internet. For more information, see RFC 1700.	Some of these addresses are reserved, for example, 224.0.1.1 is used for Network Time Protocol (NTP).
239.0.0.0 to 239.255.255.255	Limited scope addresses used for local groups and organizations. For more information, see RFC 2365.	Routers are configured with filters to prevent multicasts to these addresses from leaving the local system.

Creating multicast security policies requires multicast firewall addresses. You can add multicast firewall addresses by going to Firewall Objects > Address > Addresses and selecting Create New > Multicast Address. The factory default configuration includes multicast addresses for Bonjour (224.0.0.251-224.0.0.251, EIGRP (224.0.0.10-224.0.0.100), OSPF (224.0.0.5-224.0.0.60), all_hosts (224.0.0.1-224.0.0.1), and all_routers (224.0.0.2-224.0.0.2).