Bug #13610


VLAN ID of 0 Not Accepted in CE 2.7 or Plus 23.01

Added by Kris Phillips over 1 year ago. Updated over 1 year ago.

Not a Bug
Web Interface
Target version:
Start date:
Due date:
% Done:


Estimated time:
Plus Target Version:
Release Notes:
Affected Version:
Affected Architecture:


FreeBSD now supports VLAN tagging of 0 for interfaces, which is important for some ISPs for uplinks. However, the webConfigurator still produces an error that this is not valid when attempting to create an interface for VLAN ID of 0. We should update our sanity checks to allow for this circumstance now that it is valid.

Actions #1

Updated by Steve Wheeler over 1 year ago

  • Status changed from New to Not a Bug

Creating VLAN with VLAN ID 0 is still invalid:

[2.7.0-DEVELOPMENT][admin@cedev.stevew.lan]/root: ifconfig em0.0 create
ifconfig: invalid vlan tag

To create priority tagged traffic you need to set the PCP value on an interface:

[2.7.0-DEVELOPMENT][admin@cedev.stevew.lan]/root: ifconfig em0 pcp 4
[2.7.0-DEVELOPMENT][admin@cedev.stevew.lan]/root: ifconfig em0 
em0: flags=8863<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
    description: WAN
    ether d2:43:8f:91:74:e7
    pcp 4
    inet6 fe80::d043:8fff:fe91:74e7%em0 prefixlen 64 scopeid 0x1
    inet netmask 0xffffff00 broadcast
    media: Ethernet autoselect (1000baseT <full-duplex>)
    status: active

That will than send traffic tagged with vlan id 0 and the pcp tag set.


Actions #2

Updated by Patch Public over 1 year ago

Steve Wheeler wrote in #note-1:

That will than send traffic tagged with vlan id 0 and the pcp tag set.

It is surprising to me that a system is designed to set a value to zero by setting another parameter and having as a side effect the un-initialised value of a parameter not set is what is desired outcome.

To explain my confusion
802.1Q tag format consist of
a 16 bit Tag protocol identifier (TPID) field set to 0x8100
a 16 bit Tag control information (TCI) field consisting of
... a 03 bit Priority code point (PCP)
... a 01 bit Drop eligible indicator (DEI)
... a 12 bit VLAN identifier (VID)

A case could be made to add the ability to set the 16 bit TCI directly
I can understand the value in being able to set the VID to 0 using the existing GUI (perhaps with a warning that this is not valid only in special circumstances.
I don't understand why setting the 3 bit PCP field should be the recommended way of setting the 12bit VID being set to zero.

Clearly I'm not an expert in network protocols so perhaps it is perfectly logical. It just seems a counter intuitive system design approach to me.


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