MULTICAST_IP_ADDR

For

IP Address Traffic

System

Purpose

To select different multicast addresses.

Value

IP address

Guidelines

IP multicast addresses, also known as group addresses, are in the class D range of 224.0.0.0 to 239.255.255.255 as defined by setting the first four high order bits to 1110.

In network prefix or Classless Inter-Domain Routing (CIDR) notation, IP multicast addresses are summarized as 224.0.0.0/4. Multicast addresses in the range 224.0.0.0 to 224.0.0.255 (224.0.0.0/24) are reserved for the local subnet and are not forwarded by IP routers regardless of the Time to Live (TTL) in the IP header.

The IP multicast addresses from:

224.0.1.0 to 238.255.255.255 are either reserved or assigned to a multicasting application.

239.0.0.0 to 239.255.255.255 (239.0.0.0/8) are reserved for applications that can be administratively scoped.

The following are examples of reserved IP multicast addresses:

224.0.0.1–all hosts on this subnet.

224.0.0.2–all routers on this subnet.

224.0.0.5–Open Shortest Path First (OSPF) Version 2, designed to reach all OSPF routers on a network.

224.0.0.6–OSPF Version 2, designed to reach all OSPF designated routers on a network.

224.0.0.9–Routing Information Protocol (RIP) Version 2.

224.0.1.1–Network Time Protocol.

For the latest list of reserved multicast addresses, visit the Information Sciences Institute web site.

Default Value

224.0.0.29

 Caution: If you change the address, make sure that you change it on all the machines, in order to insure that they will continue "talking" with each other.

 

More information

Global parameters.