Lucent Technologies Release 8.2 Network ID Range Host ID Range Total IP Addresses, 1 to, 128.0 to

IP Addressing 1 Networking Overview

The IANA assigns a network address to an organization and a network administrator in the organization assigns the Host IDs associated with that Network ID to nodes within the organization’s network.

The following table shows the ranges of network and host IDs, and the total number of IP addresses (# network IDs times # host IDs), for each class.

	Network ID Range	Host ID Range	Total IP
			Addresses
Class A	7 bits	24 bits	2.1 Billion
	126 Networks:	16.8 Million Hosts per	50%
		network:
	1 to 126
		0.0.1 to 255.255.254
Class B	14 bits,	16 bits	1.1 Billion
	16,382 Networks:	65,534 Hosts per network	25%
	128.0 to 191.255	0.1 to 255.254
Class C	21 bits,	8 bits	0.5 Billion
	2.1 Million Networks:	254 Hosts per network:	12.5%
	192.0.0 to 233.255.255	1 to 254
Classes			0.5 Billion
D&E			12.5%

You can tell the class of an IP address by the first octet. For example, 191.221.30.101 is a Class B address and 192.221.30.101 is a Class C address.

Private IP Address Addresses on the Internet need to be unique to avoid ambiguity in message routing over the Internet. To insure uniqueness, the Internet Assigned Number Authority (IANA) controls the use of IP addresses. Organizations that maintain private networks that never communicate with the Internet can use arbitrary IP addresses as long as they are unique within the private network. To help prevent the duplication of IP addresses on the Internet, the IANA has reserved the following ranges of IP addresses for private networks:

1 Class A networks: 16.6 Million addresses: 10.0.0.0 --> 10.255.255.255

16 Class B networks: 1 Million addresses: 172.16.0.0 --> 172.31.255.255

256 Class C networks: 65,000 addresses:192.168.0.0 --> 192.168.255.255

These IP addresses can be used repeatedly in separate private networks, which are not connected to the Internet. Routing tables prohibit the propagation of these addresses over the Internet. (See RFC 1918). All other IP addresses are unique and must be assigned by the IANA or ISP.

Administration for Network Connectivity
555-233-504 — Issue 1 — April 2000	CID: 77730	15