### Identification

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 Subnetting
Écrit par CCNA
26-05-2008
• Subnetting : process of splitting one big network into multiple smaller networks by borrowing bits from the host part to the network part
--> more networks, less hosts per network
• Subnetting procedure through the example : 192.168.10.0/26
• Step 1 : Identify the IP class
192.168.10.0/26 (classless) --> 192.168.10.0/24 (C- class)
• Step 2 : Expand the host part      27 26 25 24 23 22 21 20 1 1 0 0 0 0 0 0
--> 27+26 = 128+64 = 192
• Step 3 : Determine the number of subnets
M = nb of bits reserved to the network --> 2M-2 = 22-2 = 2 subnets available
• Step 4 : Determine the number of hosts per subnet
N = nb of bits reserved to hosts --> 2N-2 = 26-2 = 64-2 = 62 hosts per subnet
• Step 5 : Calculate the block size
Block size = 256-nb of bits reserved to the network --> Block size = 256-192 = 64
• Step 6 : Determine the subnet mask
Subnet mask --> networkpart = all bits at 1 / host part = all bits at 0 --> Subnet mask = 255.255.255.192
• Step 7 : List the subnets and their characteristics
1st subnet = use the block size
2nd subnet = use the block size x 2
( ... )
Last subnet = Subnet mask - Block size      N° NetID IP range Broadcast 1 192.168.10.64 65-->126 192.168.10.127 2 192.168.10.128 129-->190 192.168.10.191
Dernière mise à jour : ( 02-06-2008 )