Belkin F1D001 user manual Routing and Filtering

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segments the network address into 100 subnetwork addresses. (If the Class B network address is 150.1.x.x, the address can be segmented further from 150.1.1.x through 150.1.100.x.)

A subnet mask is a 32-bit value that distinguishes the network ID from the host ID for different subnetworks on the same logical network. Like IP addresses, subnet masks consist of four octets in dotted decimal notation. You can use subnet masks to route and filter the transmission of IP packets among your subnetworks. The value “255” is assigned to octets that belong to the network ID, and the value “0” is assigned to octets that belong to the host ID.

For the example above, if you want all the devices on the subnetworks to receive each other’s IP packets, set the subnet mask to 255.255.0.0. If you want the devices on a single subnetwork only to receive IP packets from other devices on its own subnetwork, set the subnet mask to 255.255.255.0 for the devices on that subnetwork.

Subnet Mask	Routing and Filtering
0.0.0.0	IP packets are transmitted to all
	devices.
255.0.0.0	IP packets are only transmitted to
	devices whose IP address’s first octet
	matches the sender’s IP address’s first
	octet.
255.255.0.0	IP packets are only transmitted to
	devices whose IP address’s first two
	octets match the sender’s IP address’s
	first two octets.
255.255.255.0	IP packets are only transmitted to
	devices whose IP address’s first three
	octets match the sender’s IP address’s

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