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Note

You can find more information about broadcasts by reading RFC 919, “Broadcasting Internet Datagrams,” at http://www.ietf.org/rfc/rfc0919.txt?number=919.

Cisco provides many articles about multicast, including the following:

■   http://www.cisco.com/en/US/tech/tk828/technologies_white_paper09186a0080092942.shtml

■   http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/ipmulti.htm#wp1020604

IPv4 Addresses for Different Purposes

Besides the addresses in the IPv4 address range that are reserved for multicast, many of the IPv4 unicast addresses have been reserved for special purposes. Some of these addresses limit the scope or functionality of the hosts to which they are assigned. Other reserved addresses cannot be assigned to hosts. In the next sections, some of these reserved address-es will be presented.

Types of Addresses in an IPv4 Network Range

Within each IPv4 network, there are three types of addresses:

■   Network address: A special address that refers to the network

■   Broadcast address: A special address used to send data to all hosts in the network

■   Host addresses: The unicast addresses assigned to the end devices in the network

Within each network, there are two addresses that cannot be assigned to devices: network address and broadcast address. The other addresses allocated to a network are the host addresses to be assigned to the individual devices.