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I have 4 VLANs set up for our network. VLAN 50 for Servers / Firewall, VLAN 100 for Workstations, VLAN 150 for VOIP, and VLAN 200 for WiFi. What is the best practice for setting the trunk links VLAN membership? Is there a difference between the "trunk native vlan" command, and "switchport access vlan XXX"? Should I make the native VLAN for trunk links the Servers VLAN, or a completely separate VLAN?

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    From a security perspective, it is better to not have a native VLAN. The native VLAN is just the untagged VLAN, and untagged VLANs present security problems. All your trunked VLANs can have tags. The access ports do not tag because the end-devices usually cannot handle tags, but the traffic will be tagged with the VLAN number before it goes on the trunk. Placing a switchport access command on a trunk has no affect while the port is trunking.
    – Ron Maupin ♦
    May 19, 2015 at 20:01
  • So even though the trunks ports show up under a VLAN when I do a "show vlan" command, they really are not a member of that VLAN?
    – Matt Fogleman
    May 19, 2015 at 20:26
  • The access ports are VLAN members, from the perspective of the switch. They do not send or receive frames with VLAN tags. Frames coming in will get a tag placed on them before going out a trunk; frames going out the access ports will not have VLAN tags on them.
    – Ron Maupin ♦
    May 19, 2015 at 20:58
  • If i am guessing right. The access ports do not tag frames because en devices can handle them. So the frames are tagged before they got up to the trunk ports. So, with trunk native VLAN xxx, they tagged the frames with the specific native VLAN, in order to be handled from trunk ports?
    – Jim Pap
    Jun 26, 2019 at 9:59
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
    – Ron Maupin ♦
    Jan 5, 2021 at 18:40

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A trunk's native vlan is the vlan to which untagged traffic belongs. switchport access applies only to ports in access mode -- while in trunk mode, those commands do nothing at all.

Which vlan is "native" (and this not tagged) is a matter of personal preference. You could leave it at "1" and not allow "1" on the port (switchport trunk allowed vlan)

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  • Be aware that by using "switchport trunk allowed vlan X" ONLY vlan x will be allowed, all other previously allowed vlans will be denied until you add them back, which could cause unexpected netword outage. One should give all the vlans that require access on that trunk as an argument to that command at once.
    – Stef Heylen
    May 20, 2015 at 8:31

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