Operation Manual – MulticastH3C S5600 Series Ethernet Switches Chapter 1 Multicast Overview1-8packets. Class D address must not appear in the IP address field of a source IPaddress of IP packets. Class E IP addresses are reserved for future use.In unicast data transport, a data packet is transported hop by hop from the sourceaddress to the destination address. In an IP multicast environment, there are a group ofdestination addresses (called group address), rather than one address. All thereceivers join a group. Once they join the group, the data sent to this group ofaddresses starts to be transported to the receivers. All the members in this group canreceive the data packets. This group is a multicast group.A multicast group has the following characteristics:z The membership of a group is dynamic. A host can join and leave a multicastgroup at any time.z A multicast group can be either permanent or temporary.z A multicast group whose addresses are assigned by IANA is a permanentmulticast group. It is also called reserved multicast group.Note that:z The IP addresses of a permanent multicast group keep unchanged, while themembers of the group can be changed.z There can be any number of, or even zero, members in a permanent multicastgroup.z Those IP multicast addresses not assigned to permanent multicast groups can beused by temporary multicast groups.Class D IP addresses range from 224.0.0.0 to 239.255.255.255. For details, see Table1-2.Table 1-2 Range and description of Class D IP addressesClass D address range Description224.0.0.0 to 224.0.0.255Reserved multicast addresses (IP addresses forpermanent multicast groups). The IP address224.0.0.0 is reserved. Other IP addresses can beused by routing protocols.224.0.1.0 to 231.255.255.255233.0.0.0 to 238.255.255.255Available any-source multicast (ASM) multicastaddresses (IP addresses for temporary groups).They are valid for the entire network.232.0.0.0 to 232.255.255.255 Available source-specific multicast (SSM)multicast group addresses.239.0.0.0 to 239.255.255.255 Administratively scoped multicast addresses,which are for specific local use only.As specified by IANA, the IP addresses ranging from 224.0.0.0 to 224.0.0.255 arereserved for network protocols on local networks. The following table lists commonlyused reserved IP multicast addresses:
