The document discusses subnetting and provides an example of how to subnet the IP network address 192.168.1.128 into 6 subnets. It explains that subnetting allows a single network number to be shared among multiple physical networks. Each host is configured with an IP address and subnet mask, where the subnet is calculated by performing a bitwise AND of the IP address and subnet mask. The example shows how to determine the subnet mask is 255.255.255.224 when creating 6 subnets, and that each subnet can support up to 30 hosts.

1. Subnetting

2. Subnetting
 The original intent of the IP addresses was that the “network part of
the IP Address” would uniquely identify exactly one physical network.
 Subnets – single IP network number and allocate the IP addresses with
that network number to several networks.
 The mechanism by which a single network number can be shared
among multiple networks involves configuring all nodes on each
subnet with a subnet mask.

3. Subnetting
 In subnet the hosts may be on different physical networks but share a
single network number.
 Each host in the subnet is configured with IP address and Subnet mask.
The subnet number is calculated by doing “bitwise AND” between IP
address and subnet mask.

5. Subnetting
 The job of the router is also changes when subnetting is introduced.

6. Example forwarding table with subnetting

7. Subnetting
Example,
Create 6 subnets from the IP network address 192.168.1.128. Find the
subnet mask and maximum no. of node per subnet and list of networks.
 2n = No. of subnets. But we can use only 2n – 2 subnets only
 From given data,
 2n = 8, so n=3 (3 bits needed from host id). But we can use 6 subnets.
 So total possible subnets are 8, from that 6 subnets can be used.

8. Subnetting
To find subnet mask,
Default subnet mask for class c address = 255.255.255.0
In binary = 11111111.11111111.11111111.00000000
We need 3 bits,
11111111. 11111111. 11111111. 11100000 => 255.255.255.224
So subnet mask is 255.255.255.224

9. Subnetting
To find Network ID,
Binary AND between IP address and subnet mask
192.168.1.128 => 11000000. 10101000. 00000001. 10000000
255.255.255.224=> 11111111. 11111111. 11111111. 11100000
-------------------------------------------------------------------------------
192.168.1.128 => 11000000. 10101000. 00000001. 10000000
-------------------------------------------------------------------------------

10. Subnetting
To find No. of hosts per subnet,
Balance bits are 5,
So 25 - 2= 30 hosts can be in single subnet.

12. Subnetting
Example:
For the IP network address 192.128.0.128, create subnets
with 60 hosts per subnet. Find subnet mask, no. of subnets
and list of subnets.