#04 Subnet
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Why subnet
Subnetworks are networks within another network which make the networks more efficient. It allows for network traffic to travel shorter distances without the need to pass through routers for that traffic to reach its destination.
When a network receives a bit of data from a different network then it will sort to make sure that the route for those packets are the most effective/fast. IPv4 addresses have two parts and depending on the class of that IP address will determine how long some of the parts are. The 3 parts different classes are in alphabetic order, A, B and C.
| Class | First oclet decimal | First oclet binary | IP range | Subnet mask | Host/Network | # of networks | Use |
|---|---|---|---|---|---|---|---|
| Class A | 0-127 | 0XXXXXXX | 0.0.0.0-127.255.255.255 | 255.0.0.0 | 16,444,214 | 126 | Government |
| Class B | 128-191 | 10xxxxxx | 128.0.0.0-191.255.255.255 | 255.255.0.0 | 65,534 | 16,382 | Medium Companies |
| Class C | 192-223 | 110xxxxx | 192.0.0.0-223.255.255.255 | 255.255.255.0 | 254 | 2,097,150 | Small companies/LAN |
| Class D | 224-239 | 1110xxxx | 224.0.0.0-239.255.255.255 | Reserved for multicasting | |||
| Class E | 240 | 1111xxxx | 240.0.0.0-255.255.255.255 | Experimental |
Reasons why subnetting is used is because for example in a Type A IP address there can be millions of people connected to that network through their devices and could take a long time for data to transfer between two networks. This is why subnetting comes in handy: subnetting narrows down the IP address to usage within a range of devices[1].
The benefits of subnetting include:
- Reducing broadcast volume and thus network traffic
- Enabling work from home
- Allowing organizations to surpass LAN constraints such as maximum number of hosts[2]
Subnet mask
A subnet mask splits an IP address into two with the host and network addresses. The subnet mask is a 32-bit number where if it is a host bit it is all 0's whilst if it is a network it is all 1s in a way that the subnet mask can then seperate the IP addresses between network and host.
parts of an IP address
CIDR
Bibliography
[1] What is a subnet? | how subnetting works | cloudflare (no date). Cloudflare. Available at: https://www.cloudflare.com/learning/network-layer/what-is-a-subnet/ (Accessed: November 21, 2022). This is why subnetting comes in handy: subnetting narrows down the IP address to usage within a range of devices..
[2] What is subnet mask? definition & faqs (2020) Avi Networks. Available at: https://avinetworks.com/glossary/subnet-mask/ (Accessed: November 21, 2022).