Collision Domain , Vlan Tagging.

Hi,
Can any one tell me please do we have collisions in a Switch if yes 1. how to avoid Collisions in a switch and 2. Define Vlan Tagging. Can anyone please answer my two questions.
Thanks.

Hi,
1) each port on a switch is a collision domain this is called microsegmentation and you can run full-duplex so the answer is  No there are no more collisions in a switched network. apart from shared segment where there is a hub or AP attached
2)on links where multiple VLANS can travel you must have a way of differentiating the VLAN the frame is part of and so you have a field with the VLAN id which is a Tag permitting to recognize the VLAN so the switch knows on which port it can forward the frame when the tag is removed.So a frame enters a port belonging to a particuliar vlan and it is tagged with the vlan id when traversing the trunk( or tagged port) and untagged when forwarded to the destination.
In 802.1Q ther is also the concept of native vlan : frames from this vlan will have no tag, this is a compatibility feature for devices not VLAN aware.
Regards.
Alain.

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