Subject: A suggestion for the vlan(4) man page
To: None <>
From: Alaric Snell-Pym <>
List: tech-net
Date: 01/15/2007 22:16:43
Hi there!

I've just set up 802.1Q VLANs on my NetBSD 3.0 box (alas, with a vr0
interface that doesn't do the big MTUs, but never mind).

I was stuck with some head-scratching for quite a while since it
didn't seem to work with the following configuration:

vlan 1 vlanif vr0
inet netmask 0xffffff00

vlan 2 vlanif vr0
inet netmask 0xfffffff8

vlan 3 vlanif vr0
inet netmask 0xffffff00

However, a lucky accident (switching back to non-VLAN mode with an
inet address on vr0 then back to VLANs, whereupon it worked) led me
to realise I had to add:


...I'd sort of assumed that adding a VLAN to an interface would
automatically bring it up, like adding an IP address does. In
hindsight this would probably be undesirable behaviour, so I wouldn't
suggest it be done that way, but I would suggest a minor addition to
the vlan(4) man page - I was a bit uneasy about the fact that it
didn't say *anything* about the desired state of the parent interface
(or, out of interest, what would happen if I assigned an IP to
it...). Perhaps it should include something like:


        Unless explicitly configured, physical interfaces are in the
'down' state
        upon booting. If a physical interface is to be used for
vlans, it should
        be configured up:

                ifconfig tlp0 up



      The same VLAN can be created at system startup time by placing
the fol-
      lowing in /etc/ifconfig.vlan0:

            vlan 6 vlanif tlp0

      To correctly configure tlp0, the following should be placed in


Does that seem reasonable?

Alaric Snell-Pym