Multicast Addressing
345
Multicast Addressing
J
ust as with mailing lists, there are several different groups that users
or applications can subscribe to. The range of multicast addresses starts with
224.0.0.0 and goes through 239.255.255.255. As you can see, this range of
addresses falls within IP Class D address space based on classful IP assign-
ment. This is denoted by the fact that the first four bits in the first octet are
1110. Just as with regular IP addresses, there are some addresses that can be
assigned and there are ranges of reserved addresses.
It is important to recognize that the reserved addresses are categorized.
Table 9.1 depicts some of the reserved addresses and their corresponding
categories. For a full listing of these assignments, you can go to
www.isi.edu/in-notes/iana/assignments/multicast-addresses
.
T A B L E 9 . 1
IP Multicast Reserved Addresses
Address
Purpose
Reserved Category
224.0.0.0224.0.0.18
Use by network pro-
tocols
Local-link
224.0.0.1
All hosts
Local-link
224.0.0.2
All routers
Local-link
224.0.0.19224.0.0.255
Unassigned
Local-link
224.0.1.0224.0.1.255
Multicast Applica-
tions
Misc. Applications
224.0.1.1
NTP
Misc Applications
224.0.1.8
NIS+
Misc Applications
224.0.1.39
Cisco-RP-Announce
Misc Applications
224.0.1.40
Cisco-RP-Discovery
Misc Applications
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