Reference Guide for the Model RH340 Internet Access ISDN Router
7-6
Basic Routing Information
Table 7-1
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 dotted-decimal value of the
additional subnet bits. For instance, 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.
Table 7-2
displays several common netmask values in both the dotted-decimal and the mask
length formats.
Table 7-1.
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
Table 7-2.
Netmask Formats
Dotted-Decimal
Mask length
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
255.255.255.252
/30
255.255.255.254
/31
255.255.255.255
/32