VTP

[jonk34567]

In trunking of vlans how is traffic   seperated to diffrent vlans ? based on mac address ?

[Julio E. Moisa]

Hi 

The layer 2 header includes the source and destination MAC addresses, and a trunk the interface verifies the frames and put a tag indicating the VLAN which this frame belongs. So the receiving trunk interface will check the frame and its tag and send it to the destination.

:-) 

[Francesco Molino]

Hi

Vtp is a Cisco proprietary protocol to exchange vlan database between all your switches.
In terms of devices, to separate them into different vlans, you configure your switchports in access or trunk mode. Trunk means that the end device will tag the Ethernet frame with its own vlan tag it belongs to. In access, the host doesn't have any clue of the vlan it belongs to but the switch knows and the switch will add the 802.1q tag.

Then, to answer your question, to separate devices into vlans it's done by using the 802.1q tag in the Ethernet frame.

When a device in a vlan wants to communicate with another device, an arp request is sent and due to this process you can see them an ip belongs to that mac that belongs to that vlan...

I've tried to explain it in a simply way using my iPhone :-)
If you want to learn, you can read some Cisco books or others about vlan basics.

[Joseph W. Doherty]

As the others have noted, multiple VLANs passed down the same link generally are "tagged" in some fashion to distinguish them between VLANs. (Note, on Cisco devices, some frames on a trunk might not be tagged. The Cisco trunk port is configured to treat such untagged frames as a particular VLAN.)

Within the switch, how VLANs are kept is up to the architecture of the switch.