HP E3000 MPE/IX, E3000/IX manual Valid Addresses of Example Subnetwork

Networking Concepts

Subnetworks

Table 2-1		Valid Addresses of Example Subnetwork
	Subnet	Address of	Decimal Value	Possible Node	Decimal Value of
		Subnetwork in	of Subnetwork	Address on	Rightmost Byte
		Binary		Subnetwork
	1	001 (00000)	32	00001–11110	33–62
	2	010 (00000)	64	00001–11110	65–94
	3	011 (00000)	96	00001–11110	97–126
	4	100 (00000)	128	00001–11110	129–158
	5	101 (00000)	160	00001–11110	161–190
	6	110 (00000)	192	00001–11110	193–222

By looking at the binary values of two IP addresses, it is easy to tell if nodes belong to the same subnet. If they do, all the bits that make up the subnet mask will be the same between IP addresses in the subnet.

Take, for example, two IP addresses (in decimal and in binary) of subnet number 1 from Table 2-1:

192.6.12.411100 0000 0000 0110 0000 1100 0010 1001

192.6.12.551100 0000 0000 0110 0000 1100 0011 0111

The subnet mask has already been defined as:

255.255.255 224 1111 1111 1111 1111 1111 1111 1110 0000

Because the mask has all bits except the five rightmost bits set to 1, all bits except the five rightmost bits must match between nodes on the same subnet. Because the two example IP addresses from subnet 1 do match except for their five rightmost bits, they belong to the same subnet.

NOTE	Subnet addressing can be used in internetworks (networks with
	gateways).

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