I researched a lot of native VLAN tagging resources, but I still don't understand what is the difference with VLAN tagging. Can anyone explain it simply?
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2 Answers
VLAN tags are only used on trunk links. Most hosts cannot understand VLAN tags since they increase the frame size. Hosts that do understand VLAN tags may be connected with a trunk link instead of an access link.
The definition of a native VLAN frame on a trunk is that it does not contain a VLAN tag. All the frames in any other VLANs on the trunk do contain VLAN tags. Depending on the switch model and software version, each trunk link may have a different VLAN as the native VLAN, but both ends of a trunk should agree on which VLAN is the native VLAN, otherwise various problems may arise, such as traffic being sent to the wrong VLAN or incorrectly bridging two different VLANs into one broadcast domain.
answered Jan 28, 2016 at 16:34
The native VLAN is the VLAN that is assumed when there is not a VLAN tag. For example, if you have a VOIP phone connected to a switch, running on VLAN 10 and then your computer connected to the phone for network access. The computer will not tag the traffic, so either the phone or the switch will assign the VLAN to the untagged traffic as it passes through.
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In your scenario, the phone is actually a switch, and it will negotiate a trunk link with the switch, or the switch port is manually configured as a trunk. In either case, the link between the switch and the phone is a trunk link. The point is that VLAN tags are only used on trunk links, not access links.– Ron Maupin ♦Jan 28, 2016 at 16:28
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I agree that the port would be a trunk, but the phone does not need to tag the computer's traffic, it can be passed untagged, while only tagging the phone's traffic. The computer's traffic is either untagged until the phone or switch, depending on the setup, then it will be assigned to the appropriate VLAN (Native).– RylanJan 28, 2016 at 16:38