ZyXEL G-405 User Guide - Page 87
Chart 8-4 Alternative Subnet Mask Notation, Example: Two Subnets, SUBNET MASK IP ADDRESS
View all ZyXEL G-405 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 87 highlights
ZyAIR G-405 User's Guide writing the value of each octet. This is usually specified by writing a "/" followed by the number of bits in the mask after the address. For example, 192.1.1.0 /25 is equivalent to saying 192.1.1.0 with mask 255.255.255.128. The following table shows all possible subnet masks for a class "C" address using both notations. Chart 8-4 Alternative Subnet Mask Notation SUBNET MASK IP ADDRESS SUBNET MASK "1" BITS LAST OCTET BIT VALUE 255.255.255.0 /24 0000 0000 255.255.255.128 /25 1000 0000 255.255.255.192 /26 1100 0000 255.255.255.224 /27 1110 0000 255.255.255.240 /28 1111 0000 255.255.255.248 /29 1111 1000 255.255.255.252 /30 1111 1100 The first mask shown is the class "C" natural mask. Normally if no mask is specified it is understood that the natural mask is being used. Example: Two Subnets As an example, you have a class "C" address 192.168.1.0 with subnet mask of 255.255.255.0. NETWORK NUMBER HOST ID IP Address 192.168.1. 0 IP Address (Binary) 11000000.10101000.00000001. 00000000 Subnet Mask 255.255.255. 0 Subnet Mask (Binary) 11111111.11111111.11111111. 00000000 The first three octets of the address make up the network number (class "C"). You want to have two separate networks. Divide the network 192.168.1.0 into two separate subnets by converting one of the host ID bits of the IP address to a network number bit. The "borrowed" host ID bit can be either "0" or "1" thus giving two subnets; 192.168.1.0 with mask 255.255.255.128 and 192.168.1.128 with mask 255.255.255.128. IP Subnetting M