Subnet Mask & Network Design
Have you ever noticed a housing community? If you notice there will be a set of plots grouped together to build a community and that community will be provided a name. In that community each house will be identified by a house number. There will be multiple plots available and those houses get built as and when there is a requirement. Also similar types of houses will be grouped together, like all premium houses will be grouped and placed in one community and all the apartments or townhouse/row-house in another group.
There is a similar concept in the networking world. Similar devices will be grouped together. For example devices like servers hosting the same kind of applications will be grouped together, printers will be grouped together so on and so forth.
Like the housing community has a name to identify the group of houses for computer networks the group of devices is identified by a network address (also called as Network ID). Within the network there will be individual devices; like the houses in the community. And each device in the network will be identified using something called an IP Address. In our earlier post of A Network Analogy when the furniture was delivered the truck checks for the community address and once it reaches the community it checks the house number to deliver it to the right house. Similar things happens with internetwork. The IP packet (which is similar to truck in our analogy) which carries the data (furniture in our analogy) first make sure it reaches the network. Once it reaches the network it identifies right host (house in our analogy) in the network and delivers the data.
This means we need to clearly design the network so that the packets can reach the right network on the internet. The functionality that helps the network deisgner to efficiently group these set of device is subnet. To create a subnet you need 2 components
- Network
- Subnet Mask
The combination of network and subnet mask helps network designers to group the devices together.
What are the benefits of grouping these devices together with the help of subnet mask:-
Benefits of Subnet and Subnet Mask
- Identify the host and network of an IP Address
Once you see an IP address along with the mask you will be able to identify which network that IP belongs to. Like having an housing community name attached to house is going to help us understand that specific house is part of the community (eg: No. 101, Crescent Village Community, Sunnyvale City, CA, USA, 90301. We first check the community name Crescent Village Community and then we find the 101 is a house in that community); these IP Address with subnet mask is going to help internet to identify IP is part of which network.(eg 200.1.1.1/24 is the par of 200.1.1.0/24 network and 200.1.1.1 is an device that is inside that network)
- Ease of Troubleshooting
This about it, when city authority or government authority hear about the complaints from different houses that are not connected it will be very difficult for them to fix it for individual house. For example the drainage outlet is broken for few house. But when the houses are grouped in community then they need to check the connection given to the community first. This helps in easy identification issue and isolate them.
Similarly for the network administrator to find out and troubleshoot the problem reported by device is it important for group these devices into subnetworks so that the administrator can troubleshoot the network first and then go to individual devices in the network.
- Ease of Operations
When a house needs an electricity connection is it easy for city/govermment to provide it based on individual house or it is easy to approve it to entire community. Offcourse for the entire community on the approval standpoint.
When network administrator want to implement rules and restrictions in the network it does make a lot of sense to have subnet so that it is easier for them to operate. Example would be allow access to printers for employees; Allow employee network to access printer networks.
- Segmentation of Network
The most important part is, subnetting helps the administrator to segment the network. Segmentation is fundamental components of new technology like Zero Touch Network Access. Segmentation happens at different layers and network is one of the layer. The subnet along with the mask is going to sub divide your network into smaller pieces which intern helps the administrator to make specific and strict rules.