Re: vlan

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Thu, 15 Mar 2018 13:53:24 +0000
    From:        Patrick Welche <prlw1%cam.ac.uk@localhost>
    Message-ID:  <20180315135324.GG765@quark>

  | ifconfig -C certainly returns vlan, but then it looks as though I need
  | the /etc/ifconfig.vlan0 file rather than being able to try the
  | fancy variable (c.f., original message...).

Yes, ifconfig -C probably also returns bridge tun tap sl ppp ...
if you're running a GENERIC kernel. 

Two things are needed for a software interface - the kernel needs
to have the driver included (or you have to allow it to load it via
a module), and something has to say which particular pseudo-
interfaces you want configured, and provide whatever special
config each requires.

  [ Side issue:  does ifconfig -C list interface names for pseudo-interfaces
    not built in, but which can be loaded as modules ??    If it doesn't
    does the current config method work for people who use modules?  ]

  | Might need a -a -n eval \$ifconfig_$cloner or somesuch...

We could add a mechanism where some variable like that
was used to indicate which specific interfaces (of each type)
are to be configured, but it is easier for everyone really to
just use the /etf/ifconfig.${cloner}* files - it is trivial to get a
list of them, there's only one thing to do to make a new one,
or remove one ...

It really hardly seems worth the effort to add a new mechanism
just so you can use a more complex and limiting syntax to
shove all of the config in a rc.conf variable.

kre

ps: do remember when you're considering methods, that nothing
requres that you config vlan0 vlan1 ... you can just as easily
have vlan37 vlan92 and vlan1013 configured, if that seems useful
(perhaps using the interface name to indicate the vlan number
as well, for management simplicity.)