ZyXEL Communications STB-1001S Guía de usuario descargar pdf (Pagina 119)

Appendix B IP Addresses and Subnetting

STB-1001S User’s Guide

119

Figure 83 Subnetting Example: After Subnetting

In a 25-bit subnet the host ID has 7 bits, so each sub-network has a maximum of 2

– 2 or 126

possible hosts (a host ID of all zeroes is the subnet’s address itself, all ones is the subnet’s

broadcast address).

192.168.1.0 with mask 255.255.255.128 is subnet A itself, and 192.168.1.127 with mask

255.255.255.128 is its broadcast address. Therefore, the lowest IP address that can be assigned

to an actual host for subnet A is 192.168.1.1 and the highest is 192.168.1.126.

Similarly, the host ID range for subnet B is 192.168.1.129 to 192.168.1.254.

Example: Four Subnets

The previous example illustrated using a 25-bit subnet mask to divide a 24-bit address into two

subnets. Similarly, to divide a 24-bit 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 2

- 2 or 62 hosts for each subnet (a host ID of all

zeroes is the subnet itself, all ones is the subnet’s broadcast address).

Table 29 Subnet 1

IP/SUBNET MASK NETWORK NUMBER

LAST OCTET BIT

VALUE

IP Address (Decimal) 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

1 2 ... 114 115 116 117 118 119 120 121 122 123 124 ... 136 137

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ZyXEL Communications STB-1001S Guía de usuario Pagina 119