Reference Guide for the Model FR314 Cable/DSL Firewall Router
B-6 Network and Routing Basics
The following table lists the additional subnet mask bits in dotted-decimal notation. To use the
table, write down the original class netmask and replace the 0 value octets with the dott ed-de cimal
value of the additional subnet bits. For example, to partition your Class C network with subnet
mask 255.255.255.0 into 16 subnets (4 bits), the new subnet mask becomes 255.255.255.240.
The following table displays several common netmask values in both the dotted-decimal and the
masklength formats.
Note: The number 192.68.135.127 is not assigned because it is the broadcast address
of the first subnet. The number 192.68.135.128 is not assigned because it i s t he net w or k
address of the second subnet.
TableB-1. Netmask Notation Translation Table for One Octet
Number of Bits Dotted-Decimal Value
1 128
2 192
3 224
4 240
5 248
6 252
7 254
8 255
TableB-2. Netmask Formats
Dotted-Decimal Masklength
255.0.0.0 /8
255.255.0.0 /16
255.255.255.0 /24
255.255.255.128 /25
255.255.255.192 /26
255.255.255.224 /27
255.255.255.240 /28
255.255.255.248 /29