Why do you use vlan

VLAN is a custom network which is created from one or more local area networks. It enables a group of devices available in multiple networks to be combined into one logical network. Without VLANs, a broadcast sent from a host can easily reach all network devices. Each and every device will process broadcast received frames.

It can increase the CPU overhead on each device and reduce the overall network security. Hosts of VLANs will not even be aware that the communication took place. This is shown in the below picture:. A LAN is a group of computer and peripheral devices which are connected in a limited area such as school, laboratory, home, and office building.

It is a widely useful network for sharing resources like files, printers, games, and other applications. In the below example, there are 6 hosts on 6 switches having different VLANs. You need 6 ports to connect switches together. It means, if you have 24 various VLANs, you will have only 24 hosts on 45 port switches.

What benefit is there to putting each office on its own VLAN? Some folks mentioned that they have servers on their own VLAN? Don't the workstations do most of the "talking" to the servers? I have 2 DVRs. Why do these need to be in their own VLAN. Does that really only apply if you're using IP cameras? I don't have the DVRs joined to the domain so aren't they isolated enough?

I never thought about using VLANs to isolate our public computers. But, again, these computers aren't part of the domain and file permissions prevent these computers from gaining access to company data anyway, right? So why use a VLAN? I read that VLANs are useful when there are members of the same department on different floors of a building for example. But I'm not sure I get it. Could it be that some organizations are big enough that each department has its own servers? What am I missing?

VLANs do two things really well, and a few other things well. The first thing they do is to create a separate broadcast domain. Just like switches create separate collision domains, VLANs isolate broadcast traffic.

Well, let's say you've created a network that has more than one subnet - e. Granted, it's only a small packet, but on larger networks this can be a lot of overhead. The second thing VLANs do very well is to isolate traffic. Remember when we could put a packet sniffer on a hub and see everyone's packets?

Switches helped that problem by eliminated the ability to see packets that weren't sent to you unless you're using a management port of course.

A third thing VLANs do arguably the best use is to allow QoS measures to be taken on devices normally fighting for shared bandwidth. This is the classic VoIP issue. The phone and computer are connected to each other and then to the switch.

The phone is on one VLAN and the computer is on another. A fourth thing VLANs do well is to separate the network logically. Each VLAN should have its own subnet. With VLANs you don't need multiple switches for multiple subnets.

You can use VLANs to pull off some of that traffic to free up some of those addresses - I see network admins do this with printers, or IP cameras, or public facing servers. You can still use the router to provide a route to this new subnet not the most efficient use, but it works and is handy in a pinch and immediately free up IP space. Regarding the logical separation issue, you might want to separate IP camera traffic from other traffic - for security, for QoS or just to better organize things.

Hey, some of us use color coded CAT5e cables, right? You might want to logically separate different companies within a shared office space consider the professional office building with multiple single office business users. I am not going to say i am some network wiz kid, but i thought i would toss in what I know of Vlans. Switches are kinda like a bucket everything you have plugged in is either pulling out or putting something in the bucket.

A vlan just helps you divde up your bucket. Now networking is getting smarter and smarter but its still just wires and it normally wont know what should be running down each line. If you have VOIP phones on the same switch as a computer and then the computer starts downloading big files well the phone can get choppy because its talking to the same place as the computer.

You put in a vlan and now they wont block each other to the internet or to a sever. Its just a way of helping to segment your Lan so you can control it better.

Layer 3 switches add complexity, and if you already have a router and are not dealing with gigabit networks, then you're probably looking at over-kill here. In this case, none of the issues in answer [B] are applicable. I guess it's possible, but that's a lot of extra wiring that will be obsolete in -2 years. Every device is part of the same LAN, also referred to as a network or subnet. The network traffic typically is all handled by a single device that performs several functions: wireless access point, Internet router, NAT Network Address Translation , and Ethernet switch.

In a nutshell, VLANs allow a group of Ethernet devices subnet to be physically separated by many Ethernet switches but communicate as if they were all connected to the same physical Ethernet switch.

In the example below, the three VLANs have devices located on separate floors. For the Engineering computers to be on the same network across multiple building floors, VLANs are used to isolate this traffic from marketing and accounting computers. Devices in different VLANs cannot communicate when only using layer 2 switches. Layer 2 devices only inspect the destination MAC media access control addresses of Ethernet frames. A MAC address is tied to a physical piece of hardware.

In other words, a layer 2 switch allows devices in the same VLAN or subnet to communicate. Also, keep in mind, modern Ethernet switches often blur the lines between layer 2 and layer 3 capabilities.

What benefits do VLANs have over making it all one large subnet? A single subnet is simple to understand and implement but creates problems as the network grows. By creating smaller subnets, this limits the broadcast domain traffic.