Last updated on January 4, 2019
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- Why and how are Ethernet Vlans tagged? 4 answers
Why and how are Ethernet Vlans tagged? In my image, I believe I have correctly depicted how tagged networking works, going from the switch to a device. If v10, v20, and v30 are tagged, then that traffic is allowed to pass through to the client device. Since, v50 isn't tagged on this port, it's traffic would not be allowed to pass. The client device would, then, determine how to handle the traffic of the different vlans (such as an Access Point that has multiple SSID's for multiple vlans or a Host running virtual computers and the guest computers are on different vlans). Since many devices (such as our home computers) do not (to the best of my limited knowledge) have the ability to apply the 802.1Q tagged header to their traffic (basically setting the computer's network card to where it sends it's traffic using a tagged network, such as the v10, v20, or v30), the traffic coming from the computer would be rejected. In this instance, an untagged network is required. It could still pass traffic on the v10, v20, or v30, but it would require that... 1.A That the vlan be untagged at the switch (such as v20) 2.A The device has the proper IP address (such as 10.0.20.XXX) OR 1.B The device is able to tag it's traffic (such as a VoIP Phone) 2.B The device has the proper IP address (such as 10.0.20.XXX) In this final image, I believe I have depicted how a tagged & untagged switch set up functions correctly. The switch has 3 tagged and 1 untagged networks. The host computer's traffic travels on the untagged network (such as acquiring an Auto DHCP, Internet, etc). The host computer, through user set up, uses the tag within the header to route the traffic correctly. The guest networks then send their tagged traffic back through to the host server, who then relay's their traffic to the switch.
Since I'm a noob, I'm unable to post a follow up question on the following question...
- Does this accurately depict (in basic terms) how tagged & untagged traffic works?
- If this is all true, then how does the host computer send tagged traffic to the switch? Does it...