ZyXEL Communications P-660HW-T v2 - Manual (Page 303)

P-660HW-T v2 User’s Guide
Appendix F IP Subnetting 303
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 130 on page 297 ) available for subnetting.
The following table is a summary for class “B” subnet planning.
5 128 129 158 159
6 160 161 190 191
7 192 193 222 223
8 224 225 254 255
Table 142 Class C Subnet Planning
NO. “BORROWED” HOST
BITS
SUBNET MASK NO. SUBNETS
NO. HOSTS PER
SUBNET
1 255.255.255.128 (/25) 2 126
2 255.255.255.192 (/26) 4 62
3 255.255.255.224 (/27) 8 30
4 255.255.255.240 (/28) 16 14
5 255.255.255.248 (/29) 32 6
6 255.255.255.252 (/30) 64 2
7 255.255.255.254 (/31) 128 1
Table 141 Eight Subnets (continued)
SUBNET SUBNET ADDRESS FIRST ADDRESS LAST ADDRESS
BROADCAST
ADDRESS
Table 143 Class B Subnet Planning
NO. “BORROWED” HOST
BITS
SUBNET MASK NO. SUBNETS
NO. HOSTS PER
SUBNET
1 255.255.128.0 (/17) 2 32766
2 255.255.192.0 (/18) 4 16382
3 255.255.224.0 (/19) 8 8190
4 255.255.240.0 (/20) 16 4094
5 255.255.248.0 (/21) 32 2046
6 255.255.252.0 (/22) 64 1022
7 255.255.254.0 (/23) 128 510