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802.1Q tag?

RicN
Valued Contributor

802.1Q tag?


Quick question on the 802.1Q tag.

The "tagging" is done in a quite unusual way (I think) when inserting it between the Source MAC address and the Type field and I am wondering the reason for this.

Is the purpose the make the frame look like an unknown Type if it is being sent to an non-802.1Q aware device?

2 REPLIES
cenk sasmaztin
Honored Contributor

Re: 802.1Q tag?

802.1q tagging protocol

attach in ethernet frame 4byte taging information
(vlan id,priority level) and this information make only see 802.1q device

if send this packet non-802.1q avare device overlook taging information in frame

cenk
cenk

RicN
Valued Contributor

Re: 802.1Q tag?


Thank you for your answer.

>if send this packet non-802.1q avare device
>overlook taging information in frame

I am wondering if the purpose with the tagging standard, in effect replacing the EtherType from, say 0800, to the new 8100, is done the ensure that no non-802.1Q device could misinterprent it?

If the tagging was done for example first in the frame and it was sent to a non-802.1Q device, then it should assume that the VLAN-tag was part of the destination mac address?