VLANs are a layer 2 (data link layer) construct originally conceived of as a means of improving network bandwidth by allowing for multiple spanning trees on a network. This was accomplished by adding a special header, referred to as a tag, to every Ethernet frame. Each VLAN packet has a tag containing the VLAN ID for the VLAN to which it belongs, which switches and routers can then use to differentiate VLAN traffic. Several proprietary tagging mechanisms arose, but eventually the IEEE developed the 802.1Q standard for VLAN tagging. Although 802.1Q is not the sole encapsulation method for VLANs, it is the method supported by pfSense, and it is the tagging mechanism (sometimes referred to ...
Hardware, configuration, and security considerations
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