Nortel Networks NN47200-503 Subnet addressing, Network and host boundaries in IP address classes

14An Introduction to IP Routing Protocols

Class	Address Range	Mask	Number of	Nodes per
			Networks	Network
D	224.0.0.0 -
	239.255.255.254

Note: Class D addresses are primarily reserved for multicast operations although the addresses 224.0.0.5 and 224.0.0.6 are used by OSPF and 224.0.0.9 is used by RIP.

E	240.0.0.0 -
	240.255.255.255
Note: Class E addresses are reserved for research purposes.

To express an IP address in dotted-decimal notation, each octet of the IP address is converted to a decimal number and separated by decimal points. For example, the 32-bit IP address 10000000 00100000 00001010 10100111 is expressed in dotted-decimal notation as 128.32.10.167.

Each IP address class, when expressed in binary notation, has a different boundary point between the network and host portions of the address, as illustrated in "Network and host boundaries in IP address classes" (page 14). The network portion is a network number field from 8 through 24 bits. The remaining 8 through 24 bits identify a specific host on the network.

Network and host boundaries in IP address classes

Subnet addressing

Subnetworks (or subnets) are an extension of the IP addressing scheme. Subnets allow an organization to use one IP address range for multiple networks. Subnets are two or more physical networks that share a common network-identification field (the network portion of the 32-bit IP address).

Nortel Ethernet Routing Switch 5500 Series

Configuration-IP Routing Protocols

NN47200-503 03.01 Standard

5.127 August 2007

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