There may be legal reasons, however, why the VLAN networks for developers, graphics and marketing may be allowed to communicate for some purpose (say, the shared printer is in the marketing VLAN and everybody wants to print on it). You want to contain the broadcasts, have VLANs to use separate IP ranges, exert tighter control over the inter-VLAN traffic. However, having VLANs does not mean you want to prevent them from ever communicating. VLANs are just that - virtual broadcast domains spanning over a switched topology, separate and isolated on Layer2 between each other. Instead of having multiple pieces of the same hardware, you are using the same hardware and use additional mechanisms to virtualize it and create multiple instances. So VLANs are about virtualizing switches, much in a similar way to using VirtualBox or VMWare to virtualize PCs. You would either buy a separate switch (or switches) for each of these units and keep the networks physically separate, or you will use a single switched topology and instead, create the (now logically) separate networks using VLANs.

Imagine you wanted to have separate networks for, say, two or three different units in your company: developers, graphics, marketing, for security and management purposes. VLANs are used to create multiple network over a single switched physical topology. So, you want to block complete traffic between vlans, dont use it. It is generally used to route traffic between two networks that have a partial overlap. This you need to deploy on your need, entirely on your choice. But with the deployment of intervlan routing you can have cross vlan communication. Yep you are correct when you say one vlan traffic cant access other vlan's traffic. It also informs the switch that it is OK to receive Dot1Q headers on Ethernet frames, so long as the VLAN ID is equal to that of the configured Voice VLAN.Дў. The command 'Voice' VLAN only tells the router, that it should pass this VLAN information onto a Cisco IP Phone -using the CDP protocol- to inform the phone which VLAN to use for its internal phone switchport traffic to be sent on, accross the Dot1Q trunk. Access Vlan is used for data on the network and the Voice Vlan is used for Voice on the same network but with a different subnet.This allows for 1 cat 6 cable to be connected to the network and supply a user with Cisco IP Phone access and data.ДЄ Voice VLAN is no different than any other VLAN.

Router on a stick and vlan