ZyXEL MI-7248PWR User Guide - Page 283

Example: Four Subnets

Page 283 highlights

Appendix A IP Addresses and Subnetting Table 121 Subnet 2 (continued) IP/SUBNET MASK NETWORK NUMBER Subnet Address: 192.168.1.128 Lowest Host ID: 192.168.1.129 Broadcast Address: 192.168.1.255 Highest Host ID: 192.168.1.254 LAST OCTET BIT VALUE Host IDs of all zeros represent the subnet itself and host IDs of all ones are the broadcast address for that subnet, so the actual number of hosts available on each subnet in the example above is 27 - 2 or 126 hosts for each subnet. 192.168.1.0 with mask 255.255.255.128 is the subnet itself, and 192.168.1.127 with mask 255.255.255.128 is the directed broadcast address for the first subnet. Therefore, the lowest IP address that can be assigned to an actual host for the first subnet is 192.168.1.1 and the highest is 192.168.1.126. Similarly the host ID range for the second subnet is 192.168.1.129 to 192.168.1.254. Example: Four Subnets The above example illustrated using a 25-bit subnet mask to divide a class "C" address space into two subnets. Similarly to divide a class "C" address into four subnets, you need to "borrow" two host ID bits to give four possible combinations (00, 01, 10 and 11). The subnet mask is 26 bits (11111111.11111111.11111111.11000000) or 255.255.255.192. Each subnet contains 6 host ID bits, giving 26-2 or 62 hosts for each subnet (all zeroes is the subnet itself, all ones is the broadcast address on the subnet). Table 122 Subnet 1 IP/SUBNET MASK NETWORK NUMBER LAST OCTET BIT VALUE IP Address 192.168.1. 0 IP Address (Binary) 11000000.10101000.00000001. 00000000 Subnet Mask (Binary) 11111111.11111111.11111111. 11000000 Subnet Address: 192.168.1.0 Lowest Host ID: 192.168.1.1 Broadcast Address: 192.168.1.63 Highest Host ID: 192.168.1.62 Table 123 Subnet 2 IP/SUBNET MASK NETWORK NUMBER IP Address IP Address (Binary) Subnet Mask (Binary) Subnet Address: 192.168.1.64 Broadcast Address: 192.168.1.127 192.168.1. 11000000.10101000.00000001. 11111111.11111111.11111111. Lowest Host ID: 192.168.1.65 Highest Host ID: 192.168.1.126 LAST OCTET BIT VALUE 64 01000000 11000000 MS-7206 User's Guide 283

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Appendix A IP Addresses and Subnetting
MS-7206 User’s Guide
283
Host IDs of all zeros represent the subnet itself and host IDs of all ones are the broadcast
address for that subnet, so the actual number of hosts available on each subnet in the example
above is 2
7
– 2 or 126 hosts for each subnet.
192.168.1.0 with mask 255.255.255.128 is the subnet itself, and 192.168.1.127 with mask
255.255.255.128 is the directed broadcast address for the first subnet. Therefore, the lowest IP
address that can be assigned to an actual host for the first subnet is 192.168.1.1 and the highest
is 192.168.1.126. Similarly the host ID range for the second subnet is 192.168.1.129 to
192.168.1.254.
Example: Four Subnets
The above example illustrated using a 25-bit subnet mask to divide a class “C” address space
into two subnets. Similarly to divide a class “C” address into four subnets, you need to
“borrow” two host ID bits to give four possible combinations (00, 01, 10 and 11). The subnet
mask is 26 bits (11111111.11111111.11111111.
11
000000) or 255.255.255.192. Each subnet
contains 6 host ID bits, giving 2
6
-2 or 62 hosts for each subnet (all zeroes is the subnet itself,
all ones is the broadcast address on the subnet).
Subnet Address:
192.168.1.128
Lowest Host ID: 192.168.1.129
Broadcast Address:
192.168.1.255
Highest Host ID: 192.168.1.254
Table 121
Subnet 2 (continued)
IP/SUBNET MASK
NETWORK NUMBER
LAST OCTET BIT VALUE
Table 122
Subnet 1
IP/SUBNET MASK
NETWORK NUMBER
LAST OCTET BIT
VALUE
IP Address
192.168.1.
0
IP Address (Binary)
11000000.10101000.00000001.
00
000000
Subnet Mask (Binary)
11111111.11111111.11111111.
11
000000
Subnet Address: 192.168.1.0
Lowest Host ID: 192.168.1.1
Broadcast Address:
192.168.1.63
Highest Host ID: 192.168.1.62
Table 123
Subnet 2
IP/SUBNET MASK
NETWORK NUMBER
LAST OCTET BIT
VALUE
IP Address
192.168.1.
64
IP Address (Binary)
11000000.10101000.00000001.
01
000000
Subnet Mask (Binary)
11111111.11111111.11111111.
11
000000
Subnet Address: 192.168.1.64
Lowest Host ID: 192.168.1.65
Broadcast Address: 192.168.1.127
Highest Host ID: 192.168.1.126