Learn the high-level process and how a packet appears before and after adding a VLAN tag.
If configured, the VLAN tag is added to the stripped packet of both tagged and non-tagged packets in the first L2 header. The following figure shows tag addition for a non-tagged packet.
For a tagged frame, tag-addition is based on the existing tag. The operation is applied to the E-tag, VN-tag, or C-tag, as showin the following figure. Note the newly added C-tag.
S-tag and double-C tag additions are no-operation (NOOP) additions, meaning it's a computer processor instruction. The following figures shows an example of tag addition forNOOP cases.