Why do we need VLANs within the same subnet?

Question

Computer networks

If there is a subnet and you need to divide it into several "departments", then why create vlans in it, if you can simply break it into several more subnets?
If the question is incorrect, then explain why vlans are needed at all?

Answer 1

It was . In short, one vlan is a separate broadcast domain. Many subnets in one vlan - still one broadcast domain. You need to understand how Ethernet and IP work.

Answer 2

Here's a fucking riddle:
You live like this alone in a one-room apartment, and you decided (in this case, ordered) to put a Chinese to you.
So the Chinese decided to cook a donkey (TURN ON DHCP - they really have a delicacy) and so this delicacy will stink (broadcast) for the whole apartment because you have a fucking alchipan (different types of networks). And in order to get rid of this, you need to raise a concrete wall (the same VLAN, i.e., broadcast traffic) that will allow you to get rid of the stink in your room.
Conclusion: without a concrete wall, you will spend your whole life sniffing the smell of donkeys (broadcast) from another network.

Answer 3

subnetting will not prevent the user from setting himself an address from a neighboring subnet and getting into it. VLAN will not allow this.

Answer 4

VLAN (Virtual Local Area Network) - a group of devices that have the ability to interact directly with each other at the data link level , although they can be physically connected to different network switches.

Answer 5

I'll just copy the introduction from the VLAN chapter of the Cisco tutorial.
Key benefits of using VLANs include:
Security: Groups with sensitive data are separated from the rest of the network, reducing the chance of leaking sensitive information. As shown in the figure, the teachers' computers are on VLAN 10 and are completely separated from student and guest data traffic.
Lower costs: Save on expensive network infrastructure upgrades and make more efficient use of available bandwidth and uplinks to reduce costs.
Improved performance: Splitting homogeneous Layer 2 networks into multiple logical workgroups (broadcast domains) reduces unnecessary network traffic and improves performance.
Reduced broadcast domains: Dividing the network into VLANs reduces the number of devices in the broadcast domain. The network shown in the figure consists of six computers and three broadcast domains: teacher, student, and guest.
Improve IT productivity: VLANs simplify network management because users with similar network requirements share the same VLAN. When a new switch is put into service, all the rules and procedures already applied in that particular VLAN are implemented on the assigned ports. It is also easier for IT pros to identify the VLAN function by assigning it an appropriate name. In this figure, for easy identification, VLAN 10 has been named Teacher, VLAN 20 Student, and VLAN 30 Guest.
Simplified project and application management: VLANs connect users and network devices to meet business or geographic network requirements. Project management and work at the application layer is simplified through the use of separation of functions. An example of such an applied task is a platform for developing applications for e-learning for teachers.