Appendix E IP Subnetting
P-660HWP-Dx User’s Guide
40
Example Eight Subnets
Similarly use a 27-bit mask to create eight subnets (000, 001, 010, 011, 100, 101, 110 and
111).
The following table shows class C IP address last octet values for each subnet.
The following table is a summary for class “C” subnet planning.
Subnetting With Class A and Class B Networks.
For class “A” and class “B” addresses the subnet mask also determines which bits are part of
the network number and which are part of the host ID.
A class “B” address has two host ID octets available for subnetting and a class “A” address has
three host ID octets (see Table 154 on page 35) available for subnetting.
The following table is a summary for class “B” subnet planning.
Table 165 Eight Subnets
SUBNET SUBNET
ADDRESS FIRST ADDRESS LAST
ADDRESS
BROADCAST
ADDRESS
1 0 1 30 31
232 33 62 63
364 65 94 95
496 97 126 127
5128 129 158 159
6160 161 190 191
7192 193 222 223
8224 225 254 255
Table 166 Class C Subnet Planning
NO. “BORROWED” HOST
BITS SUBNET MASK NO. SUBNETS NO. HOSTS PER
SUBNET
1255.255.255.128 (/25) 2126
2255.255.255.192 (/26) 462
3255.255.255.224 (/27) 830
4255.255.255.240 (/28) 16 14
5255.255.255.248 (/29) 32 6
6255.255.255.252 (/30) 64 2
7255.255.255.254 (/31) 128 1
Table 167 Class B Subnet Planning
NO. “BORROWED” HOST
BITS SUBNET MASK NO. SUBNETS NO. HOSTS PER
SUBNET
1255.255.128.0 (/17) 232766
2255.255.192.0 (/18) 416382
3255.255.224.0 (/19) 88190