What is Subnetting ?-Subnetting is the process of diving a network into small networks and is a common task on IPV4 networks.
Before we discuss how to implement it it is useful to understand why and when we need to do it and to do that we are first going to work through a simple analogy to illustrate the problem subnetting solves ## Subnetting AnalogyAs an analogy imagine a school and we need to split it into class rooms.
Now each classroom has a desk with a computer and we have been tasked with creating a labeling system for the computers. Now say we have 30 classrooms each with a maximum of 30 students and computers. If we assign numbers to our classrooms and computers then we could have for example: computer 11, classroom 24 We need two digits for the classroom which would allow for a maximum of 100 classrooms (0-99). We need two digits for the computer which would allow for a maximum of 100 computers (0-99). If we also say that classroom numbers 0 and 99 and computer numbers 0 and 99 were reserved and not allowed to be assigned then we now have a maximum of 98 classrooms and 98 computers which is enough for own requirements. So lets create our label we could use the following scheme: - computer 11, classroom 24
- 24-11
- 11-24
- 2411
- etc
There are many possible permutations we just need to pick one and tell every one about out labeling scheme. Lets assume we go for 2411 where 24 is the classroom and 11 is the computer. So now when we see the following This we do easily in our heads once we know the labelling scheme. We could even make it easier for ourselves by creating a paper mask that we put over the label that would reveal the classroom. ## IP Addresses and SubnettingJust like in our classroom example an IP address is split into two components a So the address 10.0.2.1 is split into Network plus Node. So is the network number 10, or 10.2 or 10.0.2 ? In early IPv4 networks address classes were used to identify the number of bytes allocated to the network component. The main classes were class A,B,C. With the allocation as follows:
To determine the class you needed to examine the most significant byte (far left). - 0-127
**Class A** - 128-191
**Class B** - 192-ccc
**Class C**
## IP Subnetting- Problems with Large NetworksAll modern networks use the Ethernet data link protocol. Ethernet uses a shared media and is negatively effected when a large number of nodes are connected to the same media. This is just the same as having too many kids in the same classroom. You can equate a What would happen if you had a classroom with 100’s of desks i.e. hundreds of pupils? So even though a The solution to the problem was to split the network into small networks called sub networks or subnets. Take for example a
It is important to understand that the network part of the address is only used for Once the packet Now a network administrator can interpret the node address any way they want, and so it is possible to
The technique used to create subnets is to use a Mask. The mask effectively hides the Node component and leaves the network and sub network components. If the IP address was printed on paper we could hide the last byte by placing a paper mask over the number with three holes.
To do this on a computer we use a number which we then Here is the logic table for AND 1 and 1 =1 1 and 0 =0 0 and 1 =0 0 and 0 =0 Why is this the answer to this question? from ccna Mar 5, 2020 Last Updated: Apr 21, 2022 Question: - subnetwork 192.168.1.64
subnet mask 255.255.255.192 - subnetwork 192.168.1.32
subnet mask 255.255.255.240 - subnetwork 192.168.1.64
subnet mask 255.255.255.240 - subnetwork 192.168.1.128
subnet mask 255.255.255.192 - subnetwork 192.168.1.8
subnet mask 255.255.255.224
Because 2 bits are borrowed, the new subnet mask would be /26 or 255.255.255.192
Would love your thoughts, please comment.x ← A network administrator subnets the 192.168.10.0/24 network into subnets with /26 masks. How many equal-sized subnets are created? ← How many bits must be borrowed from the host portion of an address to accommodate a router with five connected networks? |